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ball mill machine for dressing turbine tips

important tips during zirconium ball mill operation - china jiangxi sanxin new materials

important tips during zirconium ball mill operation - china jiangxi sanxin new materials

It is widely used in cement, silicate products, new building materials, refractory materials, chemical fertilizer, black and non-ferrous metal processing and glass ceramics and other production industries, for a variety of ores and other grindable materials for dry or wet grinding.Ball mill is suitable for grinding all kinds of ore and other materials, is widely used in mineral processing, building materials and chemical industries, can be divided into dry and wet grinding methods.It can be divided into two types, grid type and overflow type, according to different discharging modes.

In recent years, the ball mill is widely used in cement, metallurgy, mining, building materials, refractory materials, chemical and thermal power and other industrial sectors, with the vigorous development of all walks of life, the application of the mill is more and more widely.

There are many factors that affect the working effect of the mill, among which the filling rate of the mill is one of the main parameters in the grinding circuit.In the grinding process, the mill mainly depends on the role of the medium to complete the grinding operation, the medium filling rate is reasonable or not directly affects the productivity of the ball mill.The production capacity and energy efficiency of ball mill can be improved obviously by accurate detection of ball loading rate of mill.

At present, some manufacturers imitate the ball mill and use the method of rolling bearing. There are many unreasonable places in the installation form of hollow shaft and rolling bearing, which brings some disadvantages to the ball mill manufacturers in the future work.In order to solve this problem, we put forward the best assembly method for you to install rolling bearing on the hollow shaft of mill.

The old method of installing rolling bearings on the hollow shaft of a mill is to process the hollow shaft into the inner diameter of the bearing. The outer top sleeve of the bearing hot device, the bearing part and the inner ring of the bearing is fixed on the hollow shaft by bolts on the inlet and outlet spiral cylinder (or the inlet and outlet bushing) for compression.In the grinding process, the inlet and outlet spiral cylinder and the fixing bolt often loosen, resulting in displacement of the top sleeve and the hollow shaft. The dust will enter the bearing box in the gap between the middle and empty shaft and the top sleeve, making the grease dirty, leading to poor lubrication, and causing the damage of the bearing from time to time.

In order to overcome the above several shortcomings, we have designed a new installation method after several years of practice and exploration, and in some manufacturers have been used in a good application.

The method is that the diameter is thickened at the part where the rolling bearing is installed on the hollow shaft of the mill, and the thin oil cooled on the hollow shaft reduces the temperature of the hollow shaft to the normal range below 60.The advantages of this bearing seat are as follows:

3. The lower seat of the bearing is equipped with oil level observation oil level, the operator can see the oil level at any time, can supplement the oil amount in time, prevent poor lubrication due to lack of oil, and avoid the occurrence of bearing damage accident.

4. The oil content of the oil chamber of the bearing seat can reduce the external diameter of the rolling bearing (on the premise of ensuring that the material inlet and outlet device is installed with sufficient strength and torque force). A flange is arranged on the connecting end face of the hollow shaft and the material inlet and outlet spiral cylinder, and it is connected with the material inlet and outlet spiral cylinder flange.On the end face of the hollow shaft from coarse to fine, a pressing bearing inner ring flange is arranged to prevent the bearing from running out axially.

5. The outer top cover of the bearing is removed to prevent dust from entering the bearing box, maintain good oil quality, and ensure the service life of the bearing and the safe and reliable operation.

6. As the diameter of the hollow shaft of the rolling bearing part is thickened, the radial distance between the rolling bearing and the inlet and outlet screw cylinder is increased, which plays a certain role in heat insulation and cooling.It plays a certain role in cooling and prolonging the service life of bearings.

In addition, the selection of grinding media also directly affects the cost. It is recommended to choose the zirconium bead of Sanxin new material, which is not only high in sphericity, but also very wear-resistant and reduces the grinding cost.

top 10 tips for improving grinding efficiency of ball mill, practical and effective! - china jiangxi sanxin new materials

top 10 tips for improving grinding efficiency of ball mill, practical and effective! - china jiangxi sanxin new materials

Ball mill grinding efficiency is low, low processing capacity, high production energy consumption, product fineness is not stable and so on is most of the peers will encounter the problem.How to effectively improve the grinding efficiency of ball mill is an important problem.Below, we share 10 ways to improve the grinding efficiency of the ball mill!

a, change the grindability of the raw ore The hardness, toughness, dissociation and structural defects of the raw ore determine the degree of grinding difficulty.Small grindability is easy to grind the ore, the mill lining plate and steel ball wear is smaller, energy consumption is also small;If not, its the other way around.Raw ore properties directly affect the productivity of the mill. In production, if the ore is difficult to grind or the ore requires fine grinding, it can be considered to take a new treatment process to change the grindability of the ore if the economic and site conditions permit: One method is to add certain chemical agents in the grinding process to improve the grinding effect and increase the grinding efficiency; Another method is to change the grindability of the ore, for example, to heat the minerals in the ore, change the mechanical properties of the whole ore, reduce hardness and so on. b, more crushing less grinding, reduce grinding granularity Large grinding particle size, the mill needs to do more work on the ore, to achieve the specified grinding fineness, the workload of the ball mill is bound to increase, then, energy consumption and power consumption will also increase. To reduce the feeding particle size of grinding, it requires the particle size of crushing products to be small, that is, to more crushing less grinding.Moreover, the efficiency of crushed ore is obviously higher than that of grinding, and the energy consumption of crushed ore is lower, about 12%-25% of the energy consumption of grinding. c. Reasonable filling rate When the speed of the ball mill is constant and the filling rate is large, the ball will hit the material more times, the grinding area is large, the grinding effect is strong, but the power consumption is also large, and the filling rate is too high, it is easy to change the motion state of the ball, and reduce the hitting effect on the large particle material.On the contrary, the filling rate is too small, and the grinding effect is weak. At present, many mines set the filling rate as 45%~50%, which is not necessarily reasonable strictly speaking, because the actual conditions of each dressing plant are different, so it is not possible to achieve the ideal grinding effect by applying others data for ball loading. It depends on the situation. d, reasonable steel ball or zirconia bead size and ratio Because the steel ball in the ball mill is in point contact with the ore, and the ball diameter is too large, the crushing force is also large, leading to the crushing of the ore along the direction of penetration force, rather than along the grain interface of different minerals with weak binding force. The crushing is not selective and does not meet the grinding purpose. In addition, in the case of the same ball filling rate, too large ball diameter leads to too few steel balls, low crushing probability, aggravated overcrushing phenomenon, and uneven product particle size.The steel ball is too small, the crushing force of the ore is small, and the grinding efficiency is low. Therefore, the precise size and ratio of the steel ball are very important to the grinding efficiency. e. Accurate addingzirconia bead In the production, the grinding effect of steel ball and ore will cause the wear of steel ball, resulting in the change of the ratio of steel ball of various sizes, affecting the grinding process and resulting in the change of the fineness of grinding products, so it needs a reasonable system of steel ball supplement to make the production stable.

f. Appropriate grinding concentration The grinding concentration affects the specific gravity of the pulp, the degree of adhesion of the ore particles around the ball and the fluidity of the pulp. The grinding concentration is low, the pulp flow is fast, and the adhesive degree of the material around the steel ball is low, so the impact and grinding effect of the steel ball on the material is weak, the ore discharging size is not qualified, and the grinding efficiency can not be played. The grinding concentration is high, the material around the steel ball adhesion degree is good, the impact and grinding effect of the steel ball on the material are good, but the pulp flow is slow, easy to cause the material over crushing, more is not conducive to improve the mill handling capacity. In production practice, the grinding concentration is often controlled by controlling the amount of ore fed by the mill, or the water supply of the mill, or adjusting the grading effect, and controlling the particle size composition and water content in the grading returned sand. g, optimize the grinding process In actual production, the grinding process can be optimized according to the ore properties of the raw ore, such as the dissemination size of useful minerals, the degree of monomer dissociation, and the dissemination size of gangue minerals.Such as pre-tailing, pre-enrichment, stage grinding, pre-classification and other operations to optimize the grinding system, on the one hand to reduce the amount of grinding, on the one hand to carry out early recovery of useful minerals. h. Improve grading efficiency The effect of classification efficiency on grinding efficiency is self-evident.High grading efficiency means that qualified particle size can be discharged in a timely and efficient manner, while low grading efficiency means that most of qualified particle size products are not discharged and return to the mill for regrinding, which is easy to cause over-grinding, thus affecting the separation effect in the later stage. The efficiency of classification can be improved by using two-stage classification or improving classification equipment. i, appropriately improve the grading sand return ratio Sand return ratio is the ratio between the sand return amount of the ball mill and the raw ore feed amount, and its size directly affects the productivity of the mill.One way to improve the sand return ratio is to increase the original ore feed, and the other way is to reduce the shaft height of the spiral classifier. However, the improvement of sand return ratio also has a certain limit.When it increases to a certain value, the productivity of the mill increases very little, and the total ore feed of the mill is close to the maximum processing capacity of the mill, which is easy to cause swelling, so the return sand ratio should not be too large. j. Automatic control of grinding system There are many variable parameters in the grinding operation, a change will inevitably cause many factors to change one after another, if the use of artificial operation control will inevitably cause the production of instability, and the automatic control of grinding operation can make the grinding classification maintain stable and suitable for the requirements of the state, also can improve the grinding efficiency. According to foreign reports, the automatic control of the grinding classification circuit can increase the production capacity by 2.5%~10%, and the power consumption can be saved by 0.4~1.4kWh/t for processing one ton of ore. In grinding process, many factors affect the grinding efficiency, many factors can only qualitative analysis, it is difficult to make quantitative analysis, this needs according to the actual production situation and the result of the qualitative analysis to comprehensive analysis, thus draws the reasonable parameters, guide field production, to reduce production costs, achieve the goal of saving energy and reducing consumption.

seven tips increasing ball mill grinding efficiency - xinhai

seven tips increasing ball mill grinding efficiency - xinhai

Through the long period operation, ball mill meets the problem of grinding efficiency descending. It impacts the normal operation of processing plant, and also causes economic losses. In actual production, how can we effectively increase ball mill grinding efficiency? Seven tips will help you.

Through the long period operation, ball mill meets the problem of grinding efficiency descending. It impacts the normal operation of processing plant, and also causes economic losses. In actual production, how can we effectively increase ball mill grinding efficiency? Seven tips will help you.

Use the table of contents below to navigate through the guide: 01 Increasing the grindability of raw ore 02 More crushing and less grinding, reducing the feeding particle size of ball mill 03 Keeping the suitable steel ball filling ratio 04 Reasonably add steel balls 05 Strictly controlling the grinding concentration of ball mill 06 Optimizing ball mill grinding flow 07 Improving classification efficiency 011.Increasing the grindability of raw ore

Commonly, the grindability is determined by the hardness, degree of dissociation, size and structure of raw ore. The small grindability means that the raw ore is easy to grind, which has relatively small wear on the liner and grinding media of the ball mill and low energy consumption. The large grindability means the raw ore is hard to grind, which has larger wear on the liner and the grinding media of ball mill and larger energy consumption. Therefore, the grindability directly influences the grinding efficiency of ball mill.

Commonly, the grindability is determined by the hardness, degree of dissociation, size and structure of raw ore. The small grindability means that the raw ore is easy to grind, which has relatively small wear on the liner and grinding media of the ball mill and low energy consumption. The large grindability means the raw ore is hard to grind, which has larger wear on the liner and the grinding media of ball mill and larger energy consumption. Therefore, the grindability directly influences the grinding efficiency of ball mill.

In production, when the raw ore is hard to grind and the required particle size is thin, we can take measures to increase raw ore grindability under economic and site permission. Such as adding chemical reagent during grinding or heating the minerals to reducing the hardness.

In production, when the raw ore is hard to grind and the required particle size is thin, we can take measures to increase raw ore grindability under economic and site permission. Such as adding chemical reagent during grinding or heating the minerals to reducing the hardness.

The larger feeding particle size is, the greater the work done by the ball mill on the ore, which impacts the grinding efficiency. To reach the eligible grinding fineness, the workload must increase. The energy consumption is also increasing.

The larger feeding particle size is, the greater the work done by the ball mill on the ore, which impacts the grinding efficiency. To reach the eligible grinding fineness, the workload must increase. The energy consumption is also increasing.

If the feeding particle size reduces, the crushing product particle size is small. It is more crushing and less grinding. Therefore, the feeding particle size is suitable, so the grinding efficiency also increases.

If the feeding particle size reduces, the crushing product particle size is small. It is more crushing and less grinding. Therefore, the feeding particle size is suitable, so the grinding efficiency also increases.

Under certain rotating speed, the larger steel ball filling ratio is, the more hits of materials and the larger grinding area is. So, the energy consumption is also large. It easily leads to the change of steel ball motion state, which reversely reduces the hit effect of large particle material. In production, the filling ratio of many mines is 45%~50%. However, it is only an approximate range, because the actual conditions of different processing plants are different. Copying blindly will not achieve the ideal grinding efficiency, it depends on the situation.

Under certain rotating speed, the larger steel ball filling ratio is, the more hits of materials and the larger grinding area is. So, the energy consumption is also large. It easily leads to the change of steel ball motion state, which reversely reduces the hit effect of large particle material. In production, the filling ratio of many mines is 45%~50%. However, it is only an approximate range, because the actual conditions of different processing plants are different. Copying blindly will not achieve the ideal grinding efficiency, it depends on the situation.

During the long period of operation, the ore grinding will lead to the wear of steel ball. It leads to the ratio change of different size steel balls. It changes the grinding product fineness and even influences the grinding efficiency of ball mill. Therefore, the operators of ball mill need to check the steel ball situation regularly, adding steel ball reasonably and ensuring the stable production of ball mill.

During the long period of operation, the ore grinding will lead to the wear of steel ball. It leads to the ratio change of different size steel balls. It changes the grinding product fineness and even influences the grinding efficiency of ball mill. Therefore, the operators of ball mill need to check the steel ball situation regularly, adding steel ball reasonably and ensuring the stable production of ball mill.

Generally, the grinding concentration influences the pulp proportion, fluidity and degree of adhesion of steel ball. The grinding concentration, the slurry flowing fast, the material is not easy to stick to steel balls, and also reduces the impact and grinding to material, leading to unqualified discharge particle size and low grinding efficiency. The grinding concentration is high, so the material is easy surrounding to the steel balls, increasing the impact and grinding to material. However, the pulp flows slow, easy to over grinding.

Generally, the grinding concentration influences the pulp proportion, fluidity and degree of adhesion of steel ball. The grinding concentration, the slurry flowing fast, the material is not easy to stick to steel balls, and also reduces the impact and grinding to material, leading to unqualified discharge particle size and low grinding efficiency. The grinding concentration is high, so the material is easy surrounding to the steel balls, increasing the impact and grinding to material. However, the pulp flows slow, easy to over grinding.

In production, controlling grinding concentration is through controlling the feeding amount, water supply, or adjusting the particle size composition of graded returned sand of control classification, helping increasing ball mill grinding efficiency.

In production, controlling grinding concentration is through controlling the feeding amount, water supply, or adjusting the particle size composition of graded returned sand of control classification, helping increasing ball mill grinding efficiency.

According to the ore characteristic of raw ore (valuable mineral inlaid granularity, monomer dissociation, gangue mineral inlaid granularity), the grinding flow is optimized, such as pre-throwing, pre-enrichment, stage grinding, pre-classification. On the one hand, it reduces the feeding amount. On the other hand, valuable minerals can be recovered in time. It increases the ball mill grinding efficiency.

According to the ore characteristic of raw ore (valuable mineral inlaid granularity, monomer dissociation, gangue mineral inlaid granularity), the grinding flow is optimized, such as pre-throwing, pre-enrichment, stage grinding, pre-classification. On the one hand, it reduces the feeding amount. On the other hand, valuable minerals can be recovered in time. It increases the ball mill grinding efficiency.

The classification efficiency has an implied influence on grinding efficiency. The high classification efficiency means that the qualified particles can be high-efficiency discharged in time. The low classification means most of the qualified particles are not discharged and returned to ball mill regrinding, which easily causes over grinding. In production, two-stage classification or improving classification equipment can increase the classification efficiency and relatively improving the grinding efficiency.

The classification efficiency has an implied influence on grinding efficiency. The high classification efficiency means that the qualified particles can be high-efficiency discharged in time. The low classification means most of the qualified particles are not discharged and returned to ball mill regrinding, which easily causes over grinding. In production, two-stage classification or improving classification equipment can increase the classification efficiency and relatively improving the grinding efficiency.

In the grinding process, there are multiple indexes influencing grinding efficiency. Many indexes are hard to quantitative analyze, which can only be qualitatively analyzed. This requires ball mill technicians to analyze according to the actual production situation on site and the results of qualitative analysis. Finally, reasonable technical parameters are obtained to guide on-site production and strive for the ideal ball mill grinding efficiency.

In the grinding process, there are multiple indexes influencing grinding efficiency. Many indexes are hard to quantitative analyze, which can only be qualitatively analyzed. This requires ball mill technicians to analyze according to the actual production situation on site and the results of qualitative analysis. Finally, reasonable technical parameters are obtained to guide on-site production and strive for the ideal ball mill grinding efficiency.

pro shop drilling equipment

pro shop drilling equipment

Our top of the lineTri-Oval System gives you the ability to drill all gripping holes without removing the ball from the jig. Mounted on a milling machine, the Tri-Oval is perfect for drilling taper-free oval thumb and finger holes that cannot be drilled on a regular drill press. The Tri-Oval comes complete with a floor stand, digital pitch scales, 40 bits, a plug cutting blade, and dial calipers.

Proprietary ultra-wide seal and heavy duty pump that locks the ball in place for worry free operation make this the best vacuum jig on the market. The pump also has a blow air funtion to "float" the ball for easy hole to hole movements. Also included is the first of its kind "touch screen" control panel for easy control.

The newly designed Oval Maker II gives you the ability to drill taper-free oval holes at a more affordable cost. The Oval Maker II comes ready to use with a floor stand. Options include bits, digital pitch scales, and a plug cutting blade.

end mills. the essential beginners guide

end mills. the essential beginners guide

End mills, slot drills, routers, milling cutters, drill bits, V-bits and burrs - what does it all mean?And which bit do I need for what job? For instance, which are the best end mills? and which is the best end mill for aluminium, and which are the best end mills for stainless steel.This article gives you the low down on milling cutters and CNC tooling.

The craft market has recently exploded with exciting compact, table top CNC Routers and Mini-milling machines. CNC Routers are now affordable enough to allow DIY enthusiasts access to this high- precision milling tool for carving and engraving.

4. The exception to this rule are diamond drill bits which have a flat end rather than pointed or fluted. (Unless it is a diamond twist drill which is not used for drilling but for expanding already existing holes such as in beads)

There are multiple types of End mills, each designed with a variety of different factors to enable you to choose the right end mill to match the material youre working on, and the type of project youre going to use it for.

Often more expensive, these coatings are added to the bit to reduce wear and friction. However, not all coatings are suitable for all materials and whilst a particular coating may be good for productivity on one material, it may be not be on another.

tips for buying your first milling machine | hackaday

tips for buying your first milling machine | hackaday

If youre interested in making things (and since youre reading this, were going to assume you are), youve almost certainly felt a desire to make metal parts. 3D printers are great, but have a lot of drawbacks: limited material options, lack of precision, and long printing times. If you want metal parts that adhere to even moderately tight tolerances, a milling machine is your only practical option. There is, after all, a very good reason that theyre essential to manufacturing.

However, it can be difficult to know where to start for the hobbyist who doesnt have machining experience. What kind of milling machine should you get? Should you buy new or used? What the heck is 3-phase power, and can you get it? These questions, among many others, can be positively overwhelming to the uninitiated. Luckily, we your friends at Hackaday are here to help give you some direction. So, if youre ready to learn, then read on! Already an expert? Leave some tips of your own in the comments!

Before we get into the details of what configuration of milling machine youll most likely want to buy, let us first point out that were only going to be talking aboutmanualmilling machines in this guide. CNC mills are a whole other beast, and theyre going to get a guide all to themselves. Manual and CNC mills share a lot in common (CNC mills are often just converted manual mills), but CNC mills have additional requirements that would over-complicate this article. So, were just covering manual machines in this post.

Modern milling machines are divided into two basic types: horizontal and vertical. This determines whether the machines spindle axis runs up and down, or side to side. Both types of machine will often have heads, columns, and tables that tilt or swivel, which means both kinds can be used for a lot of the same tasks. However, certain jobs will be easier on one machine than the other.

The difference between the machines, in practice, is more pronounced than just which way theyre oriented. A vertical machine will have the table mounted perpendicular to the spindles zero-tilt position, while a horizontal machine will have the spindle mounted parallel to the plane of the table. This introduces a fundamental difference in what kinds of jobs are practical on each type of machine.

A horizontal milling machines primary strength is the over arm, which constrains the rotating arbor on two sides. This gives it incredible rigidity, and allows the machinist to take very heavy cuts that would introduce more side load then a vertical machine could handle. The strength is so high that its entirely possible (and common) to stack multiple cutters on the arbor in order to cut, for example, a flat table with slots all in a single pass. This makes it well suited to surfacing jobs, cutting grooves and slots, and similar tasks where the part is flat in one axis.

The downside, of course, is that its much more cumbersome (and sometimes impossible) to makeparts that have cuts in all axes. This is where a vertical milling machine excels: in versatility. Youd be hard pressed to find a job that a vertical mill cant do though its sometimes a lot more time-consuming than a horizontal mill, depending on the part geometry.

Now that you know the difference, you probably already know which one you want. But, just in case, well say that you almost certainly want a vertical mill. Horizontal mills are great for a small portion of tasks, but those are also tasks that most hobbyists wont often perform. The versatility of a vertical mill lends itself well to the varied and diverse tasks that hobbyists lean towards, in contrast to the specialty production work horizontal mills are generally used for.

Hopefully, youve decided that a vertical mill is the best choice for you, otherwise this section isnt going to be very useful. Assuming you have decided on a vertical mill, youre probably curious about which features to look for, and are wondering what actually matters. Covering every detail on the subject would take an entire book, but were going to go over some of the most important things to consider.

This is a question that drives a lot of purchasing decisions, and milling machines are no different. So, does it matter? Yes and no. Milling machines have been around for alongtime, and there really arent any trade secrets when it comes to their construction. Its well-known what makes a good machine, and what doesnt. Theoretically then, any manufacturer can follow these designprinciples and make a high quality machine.

Reality, unfortunately, doesnt live up to that promise. There are two reasons for this: manufacturing quality and cost. In order to keeps costs down, many manufacturers will cut corners. They might use poor quality materials, under-powered motors, and so on. Even if the manufacturer isnt purposefully cutting corners, its entirely possible that they might just be incapable of high-quality manufacturing. Poorly made lead screws, imprecise machining, and loose tolerances can all leave you with a mill that is frustrating to use and which cant hold tolerable precision.

Therefore, its a good idea to buy a proven machine. Usually, that means going with a respectedbrand. But, some less expensive brands still produce quality machines (often clones of more expensive models). They may have fewer features, or less robust motors, but could be enough for your needs. Just be sure to read some reviews from people doing real work with them.

Small desktop milling machines can be tempting, but its best to avoid them if youre planning to mill metal. Think about the last time you had to drill a hole in steel, or had to cut off a piece with a hacksaw. Its difficult work, and takes a lot of force. Your milling machine needs to be able to apply that kind of force without flexing at all even a little bit of flex with ruin any chances of milling a part with respectable tolerances.

For that reason, the frame of the mill needs to be as heavy and rigid as possible. A small desktop machine will almost certainly be unable to mill anything harder than aluminum, and even then itll be imprecise. The wisest choice, if you want even moderate precision, is to buy a mill thats as large and heavy as you have space for.

A DRO (digital readout) is a module that can be added to each axis of a milling machine. Some machines come with them, others have them available as upgrade packages. Kits are often available to retrofit mills that didnt originally have them as an option as well. A DRO gives you a display that tells you how far youve moved the table (or quill), which makes pretty much every operation much easier.

Using a DRO isnt strictly necessary, as all mills have dials for measuring movement. However, reading them can be cumbersome and time-consuming. This is especially true when you consider backlash (slop in the screws), which is easy to compensate for when you have a DRO, since it only tells you how much the table has actually moved, as opposed to how much the handle has moved.

Like a DRO, power feed is something that can be added to each axis, and which many mills come with from the factory. It allows you to toggle a small motor which moves the table for you, so that you dont have to crank the handle yourself. This can dramatically lower fatigue, but can also give you a better surface finish on your cut as the speed stays consistent throughout the cut.

Like car enthusiasts, machinists make a big deal about horsepower. And, this isnt completely unwarranted the last thing you want is the motor stalling in the middle of a cut. That said, virtually all mills will have some way to gear down the motor to gain torque at the cost of speed. Milling steel requires high torque and low-speed, while aluminum needs the opposite.

So, you can certainly compensate for a motor without a ton of power. That may be a good idea, as motor horsepower makes a huge difference when it comes to cost. That said, you should probably avoid a mill that has any less than 1HP. Its also difficult to find high horsepower electric motors that arent 3-phase.

We dont have the room to get into how multi-phase power works, and what its advantages and disadvantages are. But, suffice it to say that you almost certainly dont have 3-phase power at home. If youve got an industrial space, you may have 3-phase power available, but even then you may not. The point is, many industrial-grade tools have 3-phase motors, which cannot be run on standard household single-phase power on their own.

That means that most of you will be limited to mills with single-phase motors. However, that often makes it possible to find 3-phase machineryfor significantly cheaper than single-phase machinery. If you find such a machine that strikes your fancy, it is possible to replace the spindle motor with a single-phase unit, or to buy or build a phase converter.

A mill/drill machine is basically a drill press that has had a 2-axis table strapped onto it. Theyre significantly cheaper than true milling machines, but thats for a reason. They really dont have the rigidity necessary for real milling, and are really only good for precise hole drilling and very light milling. Other than saving a little cash, there is no reason to buy one, as an actual milling machine can certainly drill too.

You should seriously consider buying used. Quality mills are machines that are designed to stand up to serious abuse for decades, and you can save a lot by buying used. Local industrial auctions and Craigslist are good places to look. Inspecting used machinery is kind of like inspecting a used car: make sure everything is working, that there isnt excessive wear, and that you can see its been taken care of.

Dirt and grime are okay, that can be cleaned, as long as the important bits are clean, lubricated, and not too worn. Make sure the spindle spins smoothly, has no play (measure run out if possible), and sounds good. Grab the table and jiggle it as hard as you can, and make sure you cant feel any play. Take a look at the screws to see if theyre clean and unmarred. Make sure the ways (the smooth metal that the table slides on) are clean, lubricated, and dont have gouges. If all of those things are good, and you dont notice any other red flags like cracked castings, the machine is probably solid and entirely usable. Age isnt generally considered a problem as long as its been maintained and serviced.

Milling machines are heavy; they can be anywhere from several hundred pounds on the light side, to several thousand pounds on the hefty side. Getting one back to your home or shop isnt a trivial task. If youre transporting it yourself, make sure your truck or trailer can handle the load, and that its securely strapped down. Youll also need a forklift of some kind of both sides of the delivery (to load and unload the machine).

If, like most hobbyists, you dont have a heavy flatbed truck and your own forklift, you can hire riggers to move the machine for you. Expect to pay at least a few hundred dollars (and sometimes a lot more) to have it moved, even over a short distance. If you know anyone who has this kind of equipment, its definitely worth calling in some favors youll need that money for tooling.

Once youve got your milling machine home, there are a number of purchases still to make. First and foremost, youre going to need a decent machinists vise. You dont necessarily need to spend hundreds of dollars on a Kurt vise, but youll want something that is well machined and which isnt going to loosen. A swivel mount is nice to have, but isnt a necessity.

Next, youll need a way to hold your end mills. For this, youll need collets or end millholders that match the arbor on your mill (this information should be readily available in the specs). Youll probably want to start with two or three of them in various sizes, so that you can use end mills with different shank sizes.

Speaking of end mills, youll want to order a bunch. You can buy them in bulk cheaply via eBay, which is a good idea when you first get started. Buy carbide, and a handful in a few different sizes. Make sure the shank sizes match the collets/end mill holders you bought. Generally, 2 flutes are recommended for aluminum and 4 flutes are recommended for steel. If youre not sure what youll be cutting, you can get some of each, or get some 3 flute end mills as a compromise. Expect to pay $10 and up per end mill (yes, tooling gets expensive).

Finally, you may want to consider a coolant system. These come in a few different variations, but flood coolant is usually the easiest to get setup. Despite the name, coolant does a lot more than just cool; it also lubricates and flushes away chips. Coolant systems can fairly easily be added to any milling machine, and many come with them from the factory.

Now the fun finally starts! Youre going to want to do a lot of experimenting in the beginning. Do research on feeds and speeds (and get a decent calculator for them), what different end mills are good for, and how to perform specific kinds of operations. Dont get discouraged if you break an end mill, thats why you bought extras. Practice, practice, practice, and soon youll be coming up with excuses to make precision metal parts for all of your projects.

Dont look down your nose at a mill drill. I have a unit almost identical to the Grizzly G1006 (now the G0705 I think). This sells for $1400 I got mine like new for around $500 from a friend who was leaving the country. It runs fine on 110V power and I dont know how I lived without it. Just avoid heavy cuts and climb milling. Track down the Rong Fu RF-30 which is the same thing yet again. Sure it would be nice to have a bridgeport, but consider the price, weight, size, and need to rewire your shop. If you arent doing production work where you need speed and the ability to do heavy cuts, is it worth it? A mill in the hand is worth two in the bush.

Agreed. My round column mill/drill RF-30 equivalent is working great for any purpose Ive thrown at it. The 4 Z axis travel is annoying, however, especially when switching from drill chuck to mill collets. Hasnt been a critical issue though.

Also a lot of people are afraid of dials, dont be, they are perfectly good for 99% of work once you get in the habit of keeping the backlash on one side of the dial and make sure to always back up and go forward again so your dial reads true. The only time I can think of it being a possible issue is when hogging out the inside of a pocket, but there are tricks to get around it.

When the limited Z-travel is an issue then its pretty easy to overcome by putting a dial indicator to the side of the milling head when adjusting. On the other hand, Ive used the vertical round column several times to compensate for the limited 500mm X- travel and a few times for odd pieces which I had to clamp next to the machine.

I have a few screw machine drills that are quite short. They can sometimes bypass the need to have to raise the head when you have to change to the drill chuck. I should get a full set of them some fine day.

A good set of screw machine length drill bits often costs more than a set of the same sizes, of the same quality, in the longer jobber length. Half the tool, twice the money. :P But they sure are nice when you have to get up close to the work with a mill head or lathe tailstock, plus they are usually straighter and deflect less than the jobber length bits.

This is a great mill for light duty stuff, aluminum, and even steel if you go light on cuts. Its a fantastic mill if you spend time cleaning, deburring and scraping the bearing surfaces. I cant stress how poorly these machines were finished. .

The biggest downside to these round column mills is that you lose your positioning when you raise/lower the headstock, as the headstock can rotate freely on the column. Sure, itd be nice to have a Bridgeport, but these benchtop machines are plenty good for hobby use. I got mine on Craigslist for $1000 with a bunch of collets, vises, and tooling.

Any of the round column drill/mills can be improved by filling the column with hydraulic cement. Hydraulic cement swells a little as it cures so it will be very firmly stuck and compressed in the column. The added mass helps dampen vibration and it increases the stiffness of the column so heavier cuts can be made without deflection.

Yes, many (most) homes dont have 3 phase power. But, in the USA at least, most have 240V single phase. It s not that difficult to make pseudo-3ph with capacitors. Also, for less than $300US you can an get an electronic 3ph drive, for example the Hitachi WJ200 for 1HP. Units like this convert, for example, 240V single phase to 240V 3ph. This is a good investment since it allows variable speed, programmability, and inputs for external control.

It is also true that many would not have access to a forklift. But, having moved my Bport and helped several other move theirs (or similar size machines), it can be done safely with a pickup truck, a lever, timber stacks, and pipes.

A curious thing about these converters is that ones that simply make 3 phase from single phase, without any adjustments to tweak and twiddle cost considerably more than the fancy Variable Frequency Drives which can have nearly 100 parameters to adjust and offer addon modules for serial control, modbus, some even have options for Ethernet and various other gee whiz stuff.

Theres a market for a cheap as high grade dirt phase converter that does absolutely nothing other than make proper, clean, 3 phase power from single phase input. No adjustments, no knobs, buttons LED displays etc. Such does exist but you have to pay through the nose and every other orifice to *not get* all the extra stuff.

There are also 110~115 volt 1PH to 220 volt 3PH VFDs but they top out at running a 1 horsepower 3PH motor. One should only be considered for lower power machinery that has weird stuff like a proprietary drive system or two speed motor that would be difficult or impossible to refit with a different motor.

The Chinese-made IGBT 3 phase VFDs put out pretty clean sinusoidal power for the price. Even Allen Bradley and Mitsubishi drives are dirt cheap. Our shop picked up a 10 HP drive by AB (PowerFlex line) at $700 brand new on ebay.

All you need is an old junk 3 phase motor, a couple of caps and a relayyou can make your own simple rotary converter A 2hp 3 phase junkyard motor will easy run a 1hp 3 phase mill. Just double your motor and dont worry, you will only pull whatever load you really have from the net plus whatever the idle current of the motor is.

Ultimately it barely gets used; the work space is too small for many jobs and its built so light that you have to take very light cuts. While CNC helps me ignore the time consumption, it still deters me from ever using it. In hindsight I should have saved up and bought a heavier cast iron machine. Some in the $1000-$1500 range (the Sherline was bought used for $550) offer much more rigidity and healthy increases in work space.

Size definitely matters in this subject. I once asked a wizened retired machinist whether I should buy a 6 inch chuck or 10 chuck for my lathe. His response: Well, you can always chuck small stuff in a big chuck, but you cant chuck big stuff in a small chuck. ;)

Some of the farce of it too is that just because the mill is smaller, doesnt mean it is more accurate not that Ive ran into someone with this conception. The only plus side to the Sherline is I can carry it by hand, but thats also the root problem.

But the reverse is also true: just because something is bigger/heavier doesnt make it more accurate. Some small machines are extremely accurate but, of course, because they are designed to be. Manual watchmaker machines (lathe, mill) can do extremely precise work, precision Swiss-type CNC lathes also can have accuracy almost hard to understand. Some super-precise machines can be carried in one hand but still have m precision.

Between my lathe (a small 710) and my mill, Ive found the lathe to be the much more valuable tool. Even being a dinky 710 it gets a lot of use and Ive often said its the best $500 I ever spent. I could certainly make use of something larger, but it surprised me just how often I needed something concentric and round that couldnt otherwise me done with hand tools.

Wolf, nice score! Ive been eyeing something about that size, but most the ones around here start at about $600 used. For certain I need a longer bed to be more flexible with drill sizes, but even more swing would be welcome.

IF the lathe can use the 10 chuck that is. It have to be designed for the weight/size of the larger chuck or else one can shorten the life-time of the spindle bearings, shorten the life-time of the operator (a.k.a. rapid disassembly of the chuck) or just cause vibrations reducing accuracy.

yeah i have the automation direct GS3 since i wanted sensorless vector drive for my mill, but the GS2 is also a great drive , you can pick up cheap ones on ebay too, and obv there are the chinese ones. i like automation direct because theyre really helpful and knowledge on drives and motors.

Its not (that much) about load, the VFD has relatively high frequency ripple in the output, which tends to cause fairly significant eddy currents where pure 50/60Hz doesnt, these eddy currents then like to go through the bearings, which eats them alive

Biggest problem when adding a VFD to a manual machine is staying aware of the physical gear the machine is in. Dont put it in high gear and try covering all speeds with the dang VFD you will have no torque on the slow speeds and cause yourself issues.

Interesting point as well, you can extend the speed range of a machine with a VFD too, most will allow setting their output freq all the way to 400hz! (really you would never do this but 90hz for a 50% overspeed is usually ok without worry of motor damage).

This isnt universally correct. My VFD has two different connection options. One is for high speed / high horsepower spindles and the other is for low frequency Bridgeport type motors. It works well with both.

Also, you can easily run 3 phase equiptment like 3-phase input VFDs from 1 phase 220v home outlets by derating. Derating is very easy with manual milling heads because most draw very little power in comparison to high speed spindles.

We have a Sharp almost identical to the one in the first picture in our shop at work. It is not the highest quality machine but I certainly love being able to get away from doing CAD or programming work to spend some time making chips. Fun story, I designed and built a working CNC machine on a budget of less than $175 in college to spite a prof who said that I dont possess the technical skill to do that. Fun time

They also claim to be cross platform while only supporting the unspeakable rotten fruit brand and some operating system for which you have to spend half your time struggling with updates every day. No, not for me.

Some small additions: Just a few days ago I saw a pretty extensive video from oxtoolco about judging the quality of a 2nd hand lathe. Much will be the same for a mill. https://www.youtube.com/user/oxtoolco

I dont agree with hackadays view of avoiding 3 phase equipment. VFDs are very cheap nowadays (1.5kW

VFD's also have lot's of internal parameters to adjust. I've adjusted mine on purpose so it has a relatively low torque at low rpm. This is ideal for tapping. I can use my Mill + VFD to tap blind M4 holes. Torque is easily adjusted to stop without breaking the tap when it hits the bottom of the hole. Flip a switch /potmeter and the tap reverses at high rpm. This works (probably) better than those dedicated tappig heads and is a lot cheaper

Lot's of (starting) hackers won't have room for a mill the size in this article. If you want to buy a little table top machine it's very likely a good idea to buy one with a BLDC motor. Also to consider: These small tabletop mills are a lot easier to convert to CNC than the bigger one's.

The 12 speed V-belt mill I have is a BF30 equivalent (Taiwanese, bought about 25 years ago). http://www.harborfreight.com/1-1-2-half-horsepower-heavy-duty-milling-drilling-machine-33686.html If you have something like this, PUT A VFD ON IT.

Be warned that milling/lathe/metalworking is a hobby in itself. Buying the best equipment does still not guarantee anything about the product you make on it. check out some hobby metalworking sites to get a grip how to go about these machines.

Thankfully free trade now means you can buy decent used industrial strength equipment from manufacturing businesses going out of business auctions and private salesOften with complete tooling sets and cheaper than you can buy new hobby machines for.

If you have the space Id always recommend going bigger and avoiding the light duty hobby stuff. A cheaply made machine ends up being more costly because you end up buying it two or three times because it either breaks or is under rated for those jobs you want to get done.

We rebuilt a few units, and know the run-out on old machines usually means precision work is difficult. Id often avoid a purchase if we spotted chipped bits, grinder dust, or thick paint where rust should be

I rebuilt the variable speed drive on my 1990 Acra for about $100 in belts and bearings. I shopped around, eBay, Amazon and other sites to find the best prices for name brand pieces. No cheap junk from lowest bidder in Asia.

The old plastic bushings in the sliding half of the split sheave on the motor had broke up and been flung out. Doubleplus ungood annoying because Id just had it all apart and those bushings looked fine, no cracks or wear. Thats what a decade or so of sitting around does to nylon. It goes brittle, even sealed away from light and air inside a pulley bore.

Nope, nuh uh. Turns out that some time in the later 1990s the variable speed belt drive industry decided that a 35mm shaft with a single key for the split sheave on a 3HP motor was obsolete and no manufacturer of parts for these drives would henceforth make any parts for that style of shaft and sheave. *ALL* of the manufacturers went to splined shafts for that power. I had to find some suitable plastic material and turn my own bushings. Works great, should last a very long time since they only do low speed sliding.

Bridgeport has never made a knee mill with more than a 2HP motor, and they used split sheave shafts with a single key. All the parts for *those* are still available, because Bridgeport. Had they made a mill in the early 90s with variable speed and a 3HP motor, then the bushings for a 35mm keyed shaft would still be made, because Bridgeport is Bridgeport and damn near every part for almost every mill made with that name is still available.

if the machine wont take pulley you could take the motor apart and remove the stator (the part with the wire) then dremel out a part of the case and remove the big lump from the shaft and press a pulley onto the shaft and convert an old motor into a jackshaft.

I agree with the poster who said dont dis those combo lathe mills. Ive had one for years and have done amazing stuff on it despite its limitations well worth the $1200 I spent on it. I am just now moving up to separate lathe and mill.

Machining is definitely another world, and every bit as addictive as hacking electronics and software. There is a LOT to learn to do things right (and not get hurt). A book I like a lot (among others and the plethora of online videos from oxtool and tubalcain and others) is Tabletop Machining by Joe Martin of Sherline. I dont own any Sherline equipment, not that that would not be a bad road for some people, but I have learned a lot from this book and value it.

I was planning to get a Sherline lathe after I got my mill and got hooked on all this, but then a full sized lathe came my way and I have no regrets about that. But I use the mill a lot more than the lathe.

Theres talk of horizontal mills, vertical mills, but if your canny you can get hold of a universal one instead. I have a Arno with a 40int taper and 3hp spindle motor, power feeds on all axis. For horizontal mode, slide the over arm forward, put on the supports at the front and set it up. For vertical work, theres a angle drive head that bolts onto the column where the horizontal arbour goes, and that too has 40 int taper in it, so were not talking hobby class cuts here and I have to winch it into place as its a fight getting it on by hand otherwise, although physically its smaller than my bridgeport interact cnc because of how rigid the design is in comparison to a bridgeport, itll take much heavier cuts than the bigger cnc machine. I can literally load it up until the clutch starts to slip or the burning chips get too much to tolerate with my hands on the cranks. It wasnt even big bucks, it was half the price of the manual bridgeports from the j head era when I was looking because huh, whod ever heard of arno. Universal mills also have a table that can be rotated around the cutter to generate gear angles using the horizontal arbour. So you have the advantages of both machines right there in one, with just a bit of time to switch modes.

Ive retrofitted it with a 3 axis dro, best investment ever. I did start making my own out of wixey saw tapes and a home rolled dro, but months became years and then one day my wife said just buy a kit and so I imported a sinpo from the far east. It transforms the machines user friendly-ness, and I can use toolmakers buttons and the markings on the dial just fine thanks, but being able to dial in a bolt circle, and step through it reduces the thinking time and the posibility of making part scrapping mistakes when tired or simply not thinking clearly enough. Also the point about 3ph is valid, a lot of 3ph gear is cheap because not everyone has service or wants the noise of a vfd or generator setup, and generally its better built because its designed for industrial customers to work hard day in and day out 24/7. Im lucky in that my house had 3ph, and I managed to resist the electricity company changing my outdated 3ph supply for a modern monophase one, and now enjoy the advantages it brings.

Oxtool has some good videos as mentioned, and hes also got a book thats worth reading :- Metalworking Sink or Swim: Tips and Tricks for Machinists Theres also machine shop trade secrets, another good book. Invest in some learning before jumping in. Ive had the arno now for 15 years and Im still learning tips and tricks with it, and still developing tooling.

Also, yes you can move without lifting equipment, but you need to have the ability to stop and assess if you are doing something stupid, so if you can snag someone experienced for a machine move and listen to them thats you ahead already. Generally I like to roll things on, slide them along and ease them onto very low trailers, although I remember buying the arno and we had it strapped to a pallet truck and built a ramp out of blocks and sheet to get it in the back of a panel van, so anythings possible if your sensible enough and take your time. If something falls on you, your not going to come out of it well.

If something falls on you, your not going to come out of it well. which is exactly why I didnt recommend that, haha. I think the people who that have the skills to do it without a forklift are going to know that they can anyway.

Chicken and egg though isnt it, how do you get the skills without doing it but being sensible? Pro riggers wont even let you in the premises when its being moved, let alone help along to gain experience. And some stuff is more dangerous than others, wind a mill table right down, take the head off, and skate it along on sheet or bars egyptian style and its a lot easier a move than something nasty like a big radial arm drill. That panel van /machine move was sketchy (in fact the materials we made the ramp from were from behind the back of the sellers garage because I forgot my heavy steel machine ramps and it was a 200 mile journey to go back for them), but the next 3 times I moved it, it was a lot less sketcy. I think forklift unloading can be equally as sketchy, theres always this urge to lift something, I say keep it as close the ground as possible as its got less distance to fall and take your time. I have a backhoe with bucket forks rated at 1t and Id rather unload something I cared about by hand with ramps and comealongs and winches and straps than fork something off with it with its big bouncy agri tyres etc. Maybe learning machine moving should be a subject to itself, but I doubt HaDs lawyers would let it happen for liability reasons :)

Just moving my 600 pound (as I remember right) mill-drill was an adventure. We managed it with 4 guys, an engine hoist and a pickup truck, but there were plenty of opportunities for people to get hurt. It certainly would make sense to hire people with experience and equipment to move something bigger.

Yeah, I had some potential suicides help me with something stupid stupid heavy one time, and did a safety briefing beforehand, emphasising and having them repeat it back, that if it started to topple, get the F out of the way. Anyway, all goes well until we get it to this bench which is supposedly rated to half a ton, and this beast were dealing with is about 800lb, we touch it down lightly with the A frame, honestly just kiss it down, but as soon as we let the straps go slack, one leg of the bench buckles, goes right under, and dumbnuts takes a pace forward to try and HUG the oddly shaped, sharply edged, hunk of metal that is topple sliding towards him, this is I am sure at least 2 seconds after everyone started screaming shes going, look out! anyway, I get a hand to his belt and yank, and he kinda pirouettes around it, came off a bit like a judo throw if you know what I mean, thankfully, he didnt manage to get his arms fully around for it to land on, but he did try to hip check it, and got a slight gash on his thigh.

Ive owned both a Sieg X1 micro-mill (which weighs a hundred pounds soaking wet) and its slightly-bigger brother the X2, and both of them got used for plenty of 6061 and some steel on occasion. The X1 is probably a bad choice if youre working on anything much over a couple inches but it was a lot faster than a file, and the X2 is significantly more capable.

If a refrigerator-sized machine that costs a few grand is no big deal for you then by all means get a Bridgeport, but if you need to make some RC, gun, or robot parts and the small import machines are the best you can do in terms of cash or space, theyre nothing to be ashamed of. Most of the tooling you buy and all of the skills you learn will work fine on a larger/better machine, and theyre usually easy to resell when you decide to do that.

I purchased a cheap Chinese lathe/mill/drill from ShopTask. The process of honing the gibs, aligning EVERYTHING, and changing out the motor and belts for a variable speed 3 phase motor controlled by a single phase converter REALLY taught me a lot about how these things work and the importance of always checking alignment.

Do yourself a favor and purchase some alignment tools like dial indicators with magnetic stands to measure table/spindle alignment and travel. Buy some blank drill rod, clamp it in the spindle and measure the spindle alignment relative to the table. I had to shim my head to align it properly. BUY a DRO if you dont have one. Just do it.

If you are converting to CNC, use the handle dials and the DRO in conjunction to measure backlash ALL the way in X, Y, and Z axis. If it changes when you move the table to the extremes, you probably want to replace the acme/ball screws before you convert.

Feeds and speeds are 33% of the work. 1/3 of your energy goes into measuring, marking, and alignment. The other third goes into the setup. The setup is the work mounting process which needs to be just as rigid as the machine or you have wasted a lot of time and money.

The reality of Asian Iron is there are a few machine tool manufacturers in Taiwan and China who constantly clone each others and European and American machines. Then American importers, or foreign companies that sell here, do a bit of a round robin on who sells what. When Grizzly decides to stop selling their G0731, some other company will have the manufacturer paint them a different color and put their name on it.

A nice thing about Grizzly is they have manuals online for just about everything theyve ever sold. I found out that my Frejoth 1340 metal lathe *was* sold by Grizzly as the G4016. Everyone else who sold that exact same lathe used some variation on 1340, that being the max swing and length between centers. But Grizzly? Noooo. They come up with apparently random model numbers that have nothing to do with any aspect of the machine.

If youve had a yearning for a Hardinge HLV-H lathe, there are now some clones of it with features Hardinge never had a thought of while they were producing that design. Theres one with an electronic gearbox with infinitely variable spindle to lead screw speed ratio, plus of course fixed ratios for threading. Not cheap, not at all, but still a lot lower price than the last of the model Hardinge made new, which had a six figure price.

South Bend has been a division of Grizzly for a while. Those lathes are made in Taiwan by one of the common clone machine foundries, but theyre one that takes extra care with manufacturing. The South Bend lathes are based on common Asian models but with significant differences to make them unique. In the case of the discontinued 8K, a much altered version of the common as crud 820 and 920 clones of the Emco Compact 8, they didnt change the worst parts. It got a beefier bed and completely different headstock. The quick change gearbox and apron were clearly based on the venerable Workshop 9 items. But they went and left the slides and saddle unchanged. The cross slide has a very narrow dovetail and the 8K even used the same flimsy ring with two bolts in T-slots hold down for the toolpost. To make things worse, the drive to the gearbox was via cogged belts instead of being all metal gearing. At the points where making the design better mattered most, they fell on their faces. Tis no wonder it was a poor seller and ended up being clearanced at $1500. South Bend also offers an HLV-H clone but YIPES the price.

Mention could have been made of the difference between a knee mill and a bed mill. A knee mill moves the table up and down while the head remains at a fixed elevation. A bed mill has the table stay as a fixed elevation while the head moves up and down.

The round column drill/mills are a sort of bed mill, but with the round column where the head height cant be changed without losing sideways position, they have a big disadvantage. Smaller benchtop mills tend to be the bed type, with many of them having square or rectangular columns or rails.

Knee mills have come to be mostly clones of the Bridgeport J head model. Theyre the VW Beetle of milling machines. Bridgeport produced the Series II mill, better than the J in every possible way, but like the Super Beetle, it didnt stick around long, and like VW, Bridgeport went back to making the antique design dating back to the 1930s.

The closest youll come to a benchtop knee mill is currently a Grizzly G0728 (G0729 with power feed). Thats the same head as on the G0802 and G0730 (and the other variants from Grizzly) which have taller columns for more knee travel. Far as I have been able to find, every company that has ever sold that mill style has had it with the three different column heights with different bases to put them all close to the same overall height. If youre shopping for a mill in that size class, get the G0730 or same with another name, with the tallest column because you *will* need all that knee travel someday.

I took my bp interact 2hp motor up to 200% speed on one occasion. We were in the next room shifting speed remote in case the frame exploded and the noises coming out the workshop were a bit scary. So be fairly careful how far you overdrive it. Also you may overheat it if you run it very slow with the vfd, as the fan cooling is done off the main spindle. If you are going to do this, its best to have a small motor to drive the head motor cooling fan so it runs full speed even when the main motor is lugging away at low rpms. I kept my backgear in the interact and rigged a microswitch up to the gearshift knob so the cnc control (linuxcnc) knows which gear it is in, knows which way to spin the motor for spindle forward and displays the correct rpm on the screen. If you want more rpm than the gear supports it prompts for it.

Whatever you do, dont buy any old iron if you find it for a good price. I did, but I have a weakness for war machines (just ask me about a certian Prat and Whitney lathe ). Just kidding, I bought a no-name WWII Granite State jig boring machine. It is built with the principles of a jig boring machine without the accurate measuring bits that define a jig boring machine, but it sure is rigid.

Anyway, heres the trick to buying an old iron mill: make sure you can get a common taper. Dont buy anything that uses B&S-7 taper (or really, B&S-any_taper for that matter). You wont find any tooling for reasonable prices besides crappy (but functional) collets from The Little Machine Shop or a B&S-7 to ER-32 adapter from e-Baie.

As someone who has used a Grizzily G8689 (Sieg x2 clone) against 7075, 6061 and wood I highly recommend starting with a tiny machine so that you make your big mistakes on a tiny scale. I did some really dumb things when I was new with that mill and they probably would have cost me dearly if I did them on a huge Bridgeport.

I second that. I bought a large Enco mill with only 2-axis CNC. It was very accurate and sturdy, but weighted over 2500 pounds. When I sold it on Craigslist, the buyer rolled it on pipes like the Egyptinas did with ppyramid rocks and we carefuly nudege it to my driveway where a tow truck picked it up and placed it on his truck bed. Loved the mill, but rarely used it. I now have a custom Sieg mill that can mill out 12x12x12 and does a great job for what I need to do. It runs on a PC and is dirty simple to use. Start with that, then work your way up, as your interest and needs dictate.

Ultimately it barely gets used; the work space is too small for many jobs and its built so light that you have to take very light cuts. While CNC helps me ignore the time consumption, it still deters me from ever using

I just want to point out re: 3 phase power; 3 phase generally means you have some very hefty power requirements. As such, most power companies will run 3 phase to your location for free, as theyre expecting big electric bills in the future off that 3 phase line. So, dont let the lack of 3 phase in, particularly a commercial setting, limit you on what you buy. Residential you might find a little harder to convince the power company that youre going to make it worth their while, of course.

I liked how detailed the explanation for when to buy a new or used milling machine. Being aware of red flags can save both you and your wallet from making not making the best investment. I imagine that what youre planning to use it for will also have an influence as well.

Thank you for all this great information about choosing a milling machine. One thing that really stood out to me is that you say to make sure that you choose a machine that will fit your space. It would be nice to know that it wont take up too much room in the end.

Thanks for pointing out how people should consider getting milling machines with big and rigid frames so that it can drill a hole into solid steel without any problems. My dad is looking to get into the hobby of designing model aircraft dioramas. He thinks he needs a milling machine, so this tip can certainly help him pick a heavy duty one.

When it comes to selecting whether or not to buy machinery that has a spindle, its usually better to get it used since the machine has already been used a lot of times and has proven themselves rather worthy when it comes to proper spindle usage. Another thing to consider is that the spindles spin smoothly as well as sounding good when you run themand shaking it a few times before testing them out is a good idea to see if its properly attached or no. Now that I know how to discern a machine spindle, the best thing I would be able to do with it is to use it carefully since its expensive and should make the cost back that I used for buying it!

It was great that you say to make sure that you choose a machine that will fit your space. My uncle has been thinking of buying a milling machine because his partner closed down his shop. Sins the nearly has space for his own machines, I will recommend him finding a supplier that will work with him with grew cutting solutions. https://www.chickasawmachine.com/services

I like what you said about getting a milling machine with a heavy frame. My boss wants to get some milling done in the coming months. Ill share this information with her so that she can look into her options for getting the right machine.

I can imagine that a business could really benefit from getting the right equipment and help make them more effective so that they can sell more products and do more work. It was interesting to learn about how a vertical mill can take a little longer to do a job but they can be better with versatility and make sure that the cuts can be made on all axes.

tools for profile and 3d milling |
 

 modern machine shop

tools for profile and 3d milling | modern machine shop

Trochoidal machining involves milling in a pattern of constant-radius arcs. This technique lets the tool maintain a constant feed rate through high-curvature regions of the part. (Illustration courtesy of Delcam.)

Almost any milling tool can be used in a slow, conventional milling application. But when it comes to high speed or high performance applications involving fast cutting and more numerous passes, the differences between tools become more important. Specific tool shapes have specific applications.

What follows are some tips for using different tool shapes effectively. The four basic types covered here are extensively used in 3D milling and profile milling, but within that broad range of work there are more narrow applications where a given tool type may perform more effectively. At least one of these tools deserves to be used in applications where it isnt often considered.

The important thing to know about square-end tools is that the heat generated in the cut tends to go into the square corner. In high speed milling, the cutting speed may have to be decreased in order to reduce the heat so this corner doesnt wear too quickly. In hardened metal, it is best to use this tool only if the corner is not used to cut at all. An example is finish milling of a straight sidewall surface where the part has an open bottom. In non-heat-treated materials, typical uses include roughing or finishing of straight walls.

A square-end tool that adds a corner radius permits higher cutting speeds because the heat is dispersed across a larger area of the tool. Like the cornered square-end tools, typical uses for these tools include roughing or finishing of straight walls in non-heat-treated materials. Other uses for these tools include finishing of straight sidewall surfaces in hardened materialswith or without an open bottomas well as corner picking of floors in cases where the machined corner requires a small radii.

Another application for these tools is trochoidal machining. This is a milling process in which the tool path continually re-crosses itself as the tool feeds through a pattern of constant-radius arcs. (See illustration, below left) Square-end tools with sharp corners can only be used for trochoidal machining in cases in which the cut has no bottom. But tools with corner radii can be used for trochoidal machining at various depths of cut.

Toroid cutters have a distinctive shape, shown in the photograph above, left. Do not confuse a toroid cutter with a multiple-insert button cutter. Button cutters do have important uses, but because they have multiple inserts, they dont have the accuracy to perform the way a toroid can. The toroid tools are used to rough pockets, cavities and cores at mid-range cutting speeds and fairly heavy chip loads. An even better use of toroid tools is the finishing of flat surfaces, including parting lines.

Ball cutters are, in my opinion, the most versatile tools for high speed machining. They can be used to rough any cavity, core or 3D shape. They can also be used for finishing of all materials in all hardness ranges. Because the round shape allows the heat of cutting to be absorbed into the tool across a wide area, this tool permits higher cutting speeds than other tools. It also permits a higher depth of cut, because the ball shape causes a larger percentage of the tool pressure to go up toward the spindle where rigidity is high, as opposed to sideways, where the rigidity is less. The same effect decreases tool vibration, which further helps to control heat. Given the combination of speed and depth of cut that results from these advantages, a ball cutter can achieve a high metal removal rate compared to the other tool types described. (See example below.)

For slotting, pocketing and machining ribs, a cylindrical end mill is often used because the shape of this tool seems to correspond to the shape of each of these features. However, a ball cutter can perform well in these applications, too. For example, I would machine a deep slot, whether open-ended or closed, by using a ballnose tool along with shallow ramp and Z-level milling techniques typical of high speed machining. The slot could be produced much faster this way than through milling with a cylindrical end mill. Also, the side walls would probably have better straightness and perpendicularity with the rest of the part, instead of being tapered as they often are when a long end mill deflects. Ribs can be machined in a similar way.

One application I have observed involved milling 3/4-inch-wide slots in P20 steel that were 5 inches long and 2 inches deep. A cross hole in the middle of the part created an interrupted cut. Originally, six slots were finish milled in 30 minutes, not including the roughing time. But with high speed machining techniques using a ball cutter, six slots were roughed and finished in a combined operation that lasted only 10 minutes.

The more common twist drill point geometries often are not the best for the job at hand. By choosing the best point for the material being drilled, it is possible to achieve better tool life, hole geometry, precision, and productivity.

With macros and canned cycles resident in the CNC on most contemporary turning centers, single point turning of OD threads can seem like almost a default process decision. However, for numerous applications, OD thread rolling has inherent advantages as an alternative to cutting threads.

Applying ceramic inserts is not a simple substitution of one cutting tool material for another. There are significant process considerations that shops should examine carefully in order to realize performance and tool life expectations from ceramic inserts. Here's a look at some of the ways they are used.

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