If you’re interested in making things (and since you’re reading this, we’re going to assume you are), you’ve 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 they’re essential to manufacturing.
However, it can be difficult to know where to start for the hobbyist who doesn’t 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 you’re 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 you’ll most likely want to buy, let us first point out that we’re only going to be talking about manual milling machines in this guide. CNC mills are a whole other beast, and they’re 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, we’re just covering manual machines in this post.
Modern milling machines are divided into two basic types: horizontal and vertical. This determines whether the machine’s 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 they’re oriented. A vertical machine will have the table mounted perpendicular to the spindle’s 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 machine’s 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 it’s 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 it’s much more cumbersome (and sometimes impossible) to make parts that have cuts in all axes. This is where a vertical milling machine excels: in versatility. You’d be hard pressed to find a job that a vertical mill can’t do — though it’s 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, we’ll 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 won’t 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, you’ve decided that a vertical mill is the best choice for you, otherwise this section isn’t going to be very useful. Assuming you have decided on a vertical mill, you’re 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 we’re 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 a long time, and there really aren’t any trade secrets when it comes to their construction. It’s well-known what makes a good machine, and what doesn’t. Theoretically then, any manufacturer can follow these design principles and make a high quality machine.
Reality, unfortunately, doesn’t 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 isn’t purposefully cutting corners, it’s 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 can’t hold tolerable precision.
Therefore, it’s a good idea to buy a proven machine. Usually, that means going with a respected brand. 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 it’s best to avoid them if you’re 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. It’s 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 it’ll be imprecise. The wisest choice, if you want even moderate precision, is to buy a mill that’s 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 didn’t originally have them as an option as well. A DRO gives you a display that tells you how far you’ve moved the table (or quill), which makes pretty much every operation much easier.
Using a DRO isn’t 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 don’t 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 isn’t 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. It’s also difficult to find high horsepower electric motors that aren’t 3-phase.
We don’t have the room to get into how multi-phase power works, and what it’s advantages and disadvantages are. But, suffice it to say that you almost certainly don’t have 3-phase power at home. If you’ve 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 machinery for 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. They’re significantly cheaper than true milling machines, but that’s for a reason. They really don’t 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.
By this point, you should have a pretty good understanding of what matters in a milling machine. Now it’s time to dive into how you should go about buying one.
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 isn’t excessive wear, and that you can see it’s 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 can’t feel any play. Take a look at the screws to see if they’re clean and unmarred. Make sure the ways (the smooth metal that the table slides on) are clean, lubricated, and don’t have gouges. If all of those things are good, and you don’t notice any other red flags like cracked castings, the machine is probably solid and entirely usable. Age isn’t generally considered a problem as long as it’s 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 isn’t a trivial task. If you’re transporting it yourself, make sure your truck or trailer can handle the load, and that it’s securely strapped down. You’ll also need a forklift of some kind of both sides of the delivery (to load and unload the machine).
If, like most hobbyists, you don’t 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, it’s definitely worth calling in some favors — you’ll need that money for tooling.
Once you’ve got your milling machine home, there are a number of purchases still to make. First and foremost, you’re going to need a decent machinist’s vise. You don’t necessarily need to spend hundreds of dollars on a Kurt vise, but you’ll want something that is well machined and which isn’t going to loosen. A swivel mount is nice to have, but isn’t a necessity.
Next, you’ll need a way to hold your end mills. For this, you’ll need collets or end mill holders that match the arbor on your mill (this information should be readily available in the specs). You’ll 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, you’ll 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 you’re not sure what you’ll 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! You’re 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. Don’t get discouraged if you break an end mill, that’s why you bought extras. Practice, practice, practice, and soon you’ll be coming up with excuses to make precision metal parts for all of your projects.
Don’t 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 don’t 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 aren’t 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 I’ve thrown at it. The 4″ Z axis travel is annoying, however, especially when switching from drill chuck to mill collets. Hasn’t been a critical issue though.
Also a lot of people are afraid of dials, don’t 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 it’s pretty easy to overcome by putting a dial indicator to the side of the milling head when adjusting. On the other hand, I’ve 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. It’s a fantastic mill if you spend time cleaning, deburring and scraping the bearing surfaces. I can’t stress how poorly these machines were finished. .
I’ve taken the x axis from .010″ runout to .001″ runout across. It’s taken probably 15 hours of scraping, but it’s a much more rigid machine now.
I too have a 80’s Enco Mill (rebranded Rong Fu RF-30), and it is a good machine, which is small/light enough to be transported in the back of a pickup, if needed.
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, it’d 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.
Can I take light cuts on steel with a mill drill and be able to finish just like a big mill with only more time taken and will the spindle have run out afterwards
Just so too many aren’t intimidated and avoid a good deal on a B’port class machine, I offer my opinion on the following pieces of this article. Of course, YMMV ;)
Yes, many (most) homes don’t 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 B’port 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.
Yup, you can get great deals on three phase equipment, so even with purchasing a converter it’s easy to come out ahead (and with a much better machine).
Most 220~240 volt to three phase converters top out at running a 3 horsepower motor. There are some that can go higher but the price climbs rapidly.
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.
There’s 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.
“Static” phase converters using capacitors are a thing one should just say no to. Their power output is lousy and a 3PH motor running on one loses one third of its rated power.
Plenty of people, for many years, have used the “static” converters. Yes, terrible efficiency, but, really cheap and at least turns the motor. Better than peddles. ;)
The Chinese-made IGBT 3 phase VFD’s 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.
I couldn’t agree more that size matters! I bought a Sherline ages ago to build RC Car parts with; even converted it to CNC. Ironically, once I had it going, I got into real cars.
Ultimately it barely gets used; the work space is too small for many jobs and it’s 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 can’t chuck big stuff in a small chuck.” ;)
Some of the farce of it too is that just because the mill is smaller, doesn’t mean it is more accurate… not that I’ve ran into someone with this conception. The only plus side to the Sherline is I can carry it by hand, but that’s also the root problem.
But the reverse is also true: just because something is bigger/heavier doesn’t 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 µm precision.
This is even much more true for rotary tables. Small rotary tables are often almost completely covered by any work piece without room left to clamp them properly.
Between my lathe (a small 7×10) and my mill, I’ve found the lathe to be the much more valuable tool. Even being a dinky 7×10 it gets a lot of use and I’ve often said it’s 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 couldn’t otherwise me done with hand tools.
I got my lathe for $200 at a local auction, came with everything, even the Z axis for horizontal milling:http://wolftronix.com/lathe/images/P9090028.jpg
Wolf, nice score! I’ve 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.
Nice shop setup! It looks like my bench is built in just about the same way (old picture, before more was added and it started getting much use). Still no mill or lathe yet..
T’would appear that the hobby in these two photos is cleaning. ;) Where’s the swarf? And oil stains? ;)
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.
On a side note, at the company I work for we have a 120 foot long lathe, 80 foot long surface grinder, etc. Those are some pretty darn big machines!
you can convert a three phase to single phase power with a VFD, you’re not gonna convert a 20HP at home, but a lot of mills/lathes can easily be converted.
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 they’re really helpful and knowledge on drives and motors.
Except that most motors for older equipment will not be rated for VFD drivers. i.e. people regularly destroy these machines by using such devices.
Most people in home shops will not load down their mills that much. Though it is a good idea to know the output of your VFD (how close to a sine wave it is) and to derate your motors accordingly.
It’s 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 doesn’t, these eddy currents then like to go through the bearings, which eats them alive…
you can also switch the motor out for an inverter duty motor they’re not that expensive and you have at least a manual or cnc machine.to build an adapter.
rotary phase converters aren’t that expensive either and you can often find them after being ditched for a vfd/inverter duty motor.
Biggest problem when adding a VFD to a manual machine is staying aware of the physical gear the machine is in. Don’t 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 isn’t 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 VFD’s 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.
There is no issue derating for a 220v 3phase 3hp or 5hp spindle motor with your average 30 or 50amp home dryer outlet. You just buy a 3phase VFD with double the hp of the motor.
My Yaskawa VFD and many of the cheap Chinese ones are rated for 1ph input with 3ph output. These work with less derating needed.
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 “don’t possess the technical skill to do that”. Fun time
Yup, I have one at my job too (with a 2-axis CNC setup). I get chatter on really heavy cuts, but overall it’s a nice machine.
I would never buy a machine like this if it doesn’t come with complete source code. These are just to hackable to keep within the limits of what the seller wants you to do with it.
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.
You know, so it won’t warp to shit as you try to build something, and end up wasting your time. ;-)
Those Taigs are nice light duty desktop machines. We have huge mills at work, but still have a couple little Taigs around for quick/light work.
yep, I started learning on one, still have it (control board retrofit for EMC2), and still use it for small parts.
For those that don’t understand why people do machine task splitting: The speed & depth for smaller cutters is limited, and some fine surfacing jobs (<1/8") can tie up even a larger machine for days.
Some small additions: Just a few day’s 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
Apart from the horizontal and vertical mill’s there are also the universial mills which can both be used as horizontal or vertical mill.
I don’t agree with hackaday’s view of avoiding 3 phase equipment. VFD’s are very cheap nowaday’s (1.5kW <USD200) and you can change direction & speed with the flick of a potmeter and some low voltage switches. This is especially handy if you have one of the /cheaper/hobby belt driven mills. I only use 2 of the 12 V-belt speeds on my mill nowaday's. (VFD is starting to loose a lot of torque below 30Hz. For big mill's you want a mechanical reduction which increases available torque).
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.
Addition: The foto from the “Kent USA” is actally a universal mill and not (only) a horizotal mill. The head for vertical milling is on the left of the machine hanging by it’s boom untill you need it.
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.
Sorry, I didn’t mean to imply you should avoid 3-phase. In fact, quite the opposite. I just want people to be aware of the requirements.
A buddy of mine has two motors rigged up on a furniture dolly. A single phase and a 3-phase. They’re connected via a belt and a pulley on each shaft. Not bad for a nearly free 3-phase converter.
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.
So true. And after a few year’s you’ll discover that you have spent more on toolling, accesoiries & measurement equipment than the price of the original machine…
yeah when people say when are you ever going to use those 246s… use them all the time. who knew blocks with holes could be so useful
Not only do I use the 123 blocks at the mill, but I have one at my soldering station for when you need a “heavy thing” to keep a board or a part or some wires from moving while you solder to them.
Thankfully free trade now means you can buy decent used industrial strength equipment from manufacturing businesses “going out of business” auctions and private sales…Often with complete tooling sets and cheaper than you can buy new hobby machines for.
If you have the space I’d 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.
Except that larger machines that were under serious use will have a list of problems too, but good luck finding that servo control board, manual, and or software.
We rebuilt a few units, and know the run-out on old machines usually means precision work is difficult. I’d 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.
Got it all back together, turned on the power and *hummmmmmmmm* of smooth power instead of the squeal of worn out bearings. Turned the speed crank some then *CLACK* *THUMPTHUMPTHUMPTHUMPTHUMPTHUMP*.
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 I’d just had it all apart and those bushings looked fine, no cracks or wear. That’s 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.
I think, I’ll just hit the web again and find some new ones, all the parts for these are easy to find.
Nope, nuh uh. Turns out that some time in the later 1990’s 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 90’s 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.
Buying a mill is like building a pole barn: figure out the size you think you’ll need, then go bigger. =)
or you can rewind the motor to work on 3 phase 110v so you can use the inverter from modern he washing machine.
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 don’t dis those combo lathe mills. I’ve 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.
Of course if you can afford and have space for bigger go for it, but the utility you’ll get from that machine vs. the alternative (drill press? moto-tool? :-) ) is amazing.
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 don’t 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.
Find some mentors. Most if not all machinists I know personally have bent over backwards to answer questions and show me things. There is a lot to know.
There’s 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, there’s a angle drive head that bolts onto the column where the horizontal arbour goes, and that too has 40 int taper in it, so we’re 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, it’ll 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 bridgeport’s from the j head era when I was looking because huh, who’d 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.
I’ve 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 machine’s 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. I’m 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 he’s 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 I’m 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 didn’t 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, there’s 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 I’d 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 HaD’s 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 we’re 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 “she’s 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 didn’t 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.
I’ve 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 you’re 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, they’re 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 they’re 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 don’t 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.
There’s so much to this. It’s really FRIGGIN GREAT for hacking!! It’s never ending! I highly recommend milling basics books by people like Rudy Kouhoupt.
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.
I have a small knee mill that’s exactly like a Grizzly G0731, except it’s painted green and has an Enco tag on it. Enco doesn’t sell that one anymore.
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 they’ve 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 you’ve 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. There’s 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 they’re 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 8×20 and 9×20 clones of the Emco Compact 8, they didn’t 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 can’t 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. They’re 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 didn’t stick around long, and like VW, Bridgeport went back to making the antique design dating back to the 1930’s.
The closest you’ll come to a benchtop knee mill is currently a Grizzly G0728 (G0729 with power feed). That’s 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 you’re 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.
VFD allows you to change the speed electronically, 3ph allows insta reverse for tapping. there are probably other pluses.
I have a series 1 bridgeport from the mid 60s, it has some worn lead screw nuts but other than that it works great for me!
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, don’t 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, here’s the trick to buying an old iron mill: make sure you can get a common taper. Don’t buy anything that uses B&S-7 taper (or really, B&S-any_taper for that matter). You won’t 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 it’s 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 they’re expecting big electric bills in the future off that 3 phase line. So, don’t 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 you’re going to make it worth their while, of course.
They’re not nearly so agreeable running to a residence, at least not in WI. Xcel wanted to charge $35 PER FOOT to bring another phase from the closest available point, six blocks away.
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 you’re 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 won’t 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, it’s 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 them–and shaking it a few times before testing them out is a good idea to see if it’s 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 it’s expensive and should make the cost back that I used for buying it!
I have two grizzly 0704 mill/drill, with very light use on them and both have broken the plastic speed change gear.
b oth have less than 20 hours use, mainly aluminum milling and drilling and dovetail cutting on steel.
Overheats quick, mills very slow and not accurate enough for serious work. Get something MUCH heavier would be my advice.
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12 - Frequency Converter
Variable Frequency Drive, Variable Frequency Inverter, Frequency Inverter - Simphoenix,https://www.simphoenix.com/