Air Wrench Becomes a Milling Machine Power Drawbar

We sometimes wonder if designers ever actually use their own products, or even put them through some sort of human-factors testing before putting them on the market. Consider the mechanism that secures toolholders to the spindle of a milling machine: the drawbar. Some mills require you to lock the spindle with a spanner wrench, loosen the drawbar with another wrench, and catch the released collet and tool with – what exactly?

Unwilling to have the surgical modifications that would qualify him for the Galactic Presidency, [Physics Anonymous] chose instead to modify his mill with a power drawbar. The parts are cheap and easily available, with the power coming from a small butterfly-style pneumatic wrench. The drawbar on his mill has a nearly 3/8″ square drive – we’d guess it’s really 10 mm – which almost matches up with the 3/8″ drive on the air wrench, so he whipped up a female-to-female adapter from a couple of socket adapters. The wrench mounts to a cover above the drawbar in a 3D-printed holster. Pay close attention to the video below where he goes through the Fusion 360 design; we were intrigued by the way he imported three orthogonal photos on the wrench to design the holster around. That’s a tip to file away for a rainy day.

This is a great modification to a low-cost milling machine. If you’re in the process of buying machine tools, you should really check out our handy buyer’s guides for both milling machines and lathes. It’ll let you know what features to look out for, and which you’ll have to add later.

Continue reading “Air Wrench Becomes a Milling Machine Power Drawbar”

Rolling Out a Slick Rotary Phase Converter

Home machinists can often find great deals on used industrial equipment, and many a South Bend lathe or Bridgeport milling machine has followed someone home. Then comes the moment to plug it in, and the new owner discovers that the three-phase plug needed to power the new beast is nowhere to be found in the shop. Thus commences the weeping and the gnashing of teeth.

Luckily, [Handmade Extreme] is ahead of the curve in terms of shop power, and built a rotary phase converter to power his machines. Industry generally runs on three-phase AC systems, mainly because three-phase electric motors are so much more efficient and compact than the equivalent single-phase motor. But residential electrical service is either split-phase or, in the UK where [Handmade Extreme] is based, single phase. A rotary phase converter is an electromechanical device that can generate the missing phases – in essence a three-phase motor that can run on one winding and generate the missing phases across the other windings. It needs some supporting control circuitry to do so, such as timers and contactors to switch the winding connections once the motor starts, plus capacitors for motor starting and for balancing the voltage across the phases. The control gear is DIN-rail mounted and neatly wired to a smart-looking control panel. Everything is housed in a sturdy enclosure that’s big enough to serve as a mobile tool cart. It’s a really nice job – watch the whole build in the video below.

If you’re interested in power distribution, we’ve got a primer that covers the basics. And if you’re in the market for machine tools, [Quinn]’s machine tool buyer’s guide will let you decide if a three-phase machine is worth the extra effort.

Continue reading “Rolling Out a Slick Rotary Phase Converter”

Fighting Machine Tool Chatter with a 555 Timer

Vibration is a fact of life in almost every machining operation. Whether you’re milling, drilling, turning, or grinding, vibration can result in chatter that can ruin a part. Fighting chatter has generally been a matter of adding more mass to the machine, but if you’re clever about things, chatter reduction can be accomplished electronically, too. (YouTube, embedded below.)

When you know a little something about resonance, machine vibration and chatter start to make sense. [AvE] spends quite a bit of time explaining and demonstrating resonance in the video — fair warning about his usual salty shop language. His goal with the demo is to show that chatter comes from continued excitation of a flexible beam, which in this case is a piece of stock in the lathe chuck with no tailstock support. The idea is that by rapidly varying the speed of the lathe slightly, the system never spends very long at the resonant frequency. His method relies on a variable-frequency drive (VFD) with programmable IO pins. A simple 555 timer board drives a relay to toggle the IO pins on and off, cycling the VFD up and down by a couple of hertz. The resulting 100 RPM change in spindle speed as the timer cycles reduces the amount of time spent at the resonant frequency. The results don’t look too bad — not perfect, but a definite improvement.

It’s an interesting technique to keep in mind, and a big step up from the usual technique of more mass.

Continue reading “Fighting Machine Tool Chatter with a 555 Timer”

Drill Press to Mill Conversion

Every time we look at the little short Z axis of our CNC mill, we think about converting a drill press to a mill. In theory, it seems like it ought to be easy, but we never quite get around to it. [AvE] did get around to it and made his usual entertaining video about it that you can see below. If you haven’t seen any of [AvE’s] videos before, be warned: there is a little colorful language in a spot or two.

This isn’t a CNC mill, by the way, although we suspect you could convert it. Essentially, he adds a spindle and an XY table to a Ryobi drill press. It sounds simple, but getting everything to work did take a few tricks, including a blow torch.

Actually, turns out the blow torch didn’t really do it, but we won’t spoil the final resolution to the problem. Once it was resolved, though, he did manage to do some actual milling, accompanied by some music we wouldn’t associate with [AvE].

Although billed as a “poor man’s” build, the XY table alone was about $200. So add in the cost of the drill press, the spindle, and the mill and this is still a fair chunk of cash. We’d love to see it compared to a Harbor Freight milling vise. We suspect the Harbor Freight vise might not be as good, but is the difference worth the $130 difference in price?

We’ve seen this kind of conversion done before without the colorful language. If you do this conversion and want some practice, why not build a magnetic carabiner?

Home Built PCB Mill Reportedly Doesn’t Suck

It’s 2017, and getting a PCB professionally made is cheaper and easier than ever. However, unless you’re lucky enough to be in Shenzhen, you might find it difficult to get them quickly, due to the vagaries of international shipping. Whether you want to iterate quickly on designs, or just have the convenience of speed, it can be useful to be able to make your own PCBs at home. [Timo Birnschein] had just such a desire and set about building a PCB mill that doesn’t suck.

It might sound obvious, but it bears thinking about — if you know you’re incapable of building a good PCB mill in a reasonable period of time, you might save yourself a lot of pain and lost weekends by just ordering PCBs elsewhere. [Timo] was fairly confident however that the build would be able to churn out some usable boards, however, and got to work.

The build is meant to be accessible to the average hacker who wants one. The laser cut & 3D printed parts are readily available these days thanks to online services that can manufacture for those who don’t have the machines at home. [Timo] uses a rotary multitool for a spindle, a common choice for a budget CNC build.

With the hardware complete, [Timo] has spent time working on optimising the software side of things. Through careful optimisation of the G-Code, [Timo] has been able to improve performance and reduce stress on the tooling. It’s not enough to just build a good mill — you’ve got to have your G-Code squared away as well.

Overall, the results speak for themselves. The boards don’t suck; the mill can do traces down to 8 mil, and even drill the holes. We’d love to have one on the workbench when busting out some quick prototypes. For another take on the home-built PCB mill, why not check out this snap-together version?

Restoring a Strange Milling Machine from Craigslist

[diyVT] found a real white elephant in this milling machine from Craigslist. It cost him only $200, cheap for a small mill, so it was worth the gamble. We’re not sure what to call this — it’s not exactly a gantry mill, not a horizontal mill, and definitely not a knee mill. The tag says V-Mill, made by either Pierce West or Tree Tool and Die Works, depending on which ID plate you read. The Tree has a three-phase motor, but it came with a phase converter, so it should be good to run on single phase 220 volt household power.

The machine was in good physical shape, at least until the previous owner attempted to move it out of the garage. During the move one of the cast iron chain drive handwheel brackets broke into three pieces. Cast iron is no fun to weld. It has to be pre-heated, welded with nickel rod, and slowly cooled. Some hackers would have given up or built a new part, but [diyVT] accepted the challenge. He put the puzzle pieces back together, grooved them out with an angle grinder, and welded everything. The result wasn’t pretty, but it only has to take the force of the handwheel and the 200 lb gorilla spinning it.

After a bit of work on the motor and head, including a new belt, this tree was ready to cut. [diyVT] snuck out of a family bar-b-que to cut his first chips on the new (to him) machine.

Continue reading “Restoring a Strange Milling Machine from Craigslist”

Pretty Fly for a DIY Guy

Milling machines can be pretty intimidating beasts to work with, what with the power to cut metal and all. Mount a fly cutter in the mill and it seems like the risk factor goes up exponentially. The off-balance cutting edge whirling around seemingly out of control, the long cutting strokes, the huge chips and the smoke – it can be scary stuff. Don’t worry, though – you’ll feel more in control with a shop-built fly cutter rather than a commercial tool.

Proving once again that the main reason to have a home machine shop is to make tools for the home machine shop, [This Old Tony] takes us through all the details of the build in the three-part video journey after the break. It’s only three parts because his mill released the Magic Smoke during filming – turned out to be a bad contactor coil – and because his legion of adoring fans begged for more information after the build was finished. But they’re short videos, and well worth watching if you want to pick up some neat tips, like how to face large stock at an angle, and how to deal with recovering that angle after the spindle dies mid-cut. The addendum has a lot of great tips on calculating the proper speed for a fly cutter, too, and alternatives to the fly cutter for facing large surfaces, like using a boring head.

[ThisOldTony] does make things other than tooling in his shop, but you’ll have to go to his channel to find them, because we haven’t covered too many of those projects here. We did cover his impressive CNC machine build, though. All [Tony]’s stuff is worth watching – plenty to learn.

Continue reading “Pretty Fly for a DIY Guy”