Metric And Inch Threads Fight It Out For Ultra-Precise Positioning

September 21, 2022 by Dan Maloney 20 Comments

When you’re a machinist, your stock in trade is precision, with measurements in the thousandths of your preferred unit being common. But when you’re a diemaker, your precision game needs to be even finer, and being able to position tools and material with seemingly impossibly granularity becomes really important.

For [Adam Demuth], aka “Adam the Machinist” on YouTube, the need for ultra-fine resolution machinist’s jacks that wouldn’t break the bank led to a design using off-the-shelf hardware and some 3D printed parts. The design centers around an inch-metric thread adapter that you can pick up from McMaster-Carr. The female thread on the adapter is an M8-1.25, while the male side is a 5/8″-16 thread. The pitches of these threads are very close to each other — only 0.0063″, or 161 microns. To take advantage of this, [Adam] printed a cage with compliant mechanism springs; the cage holds the threaded parts together and provide axial preload to remove backlash, and allows mounting of precision steel balls at each end to make sure the force of the jack is transmitted through a single point at each end. Each full turn of the jack moves the ends by the pitch difference, leading to ultra-fine resolution positioning. Need even more precision? Try an M5 to 10-32 adapter for about 6 microns per revolution!

While we’ve seen different thread pitches used for fine positioning before, [Adam]’s approach needs to machining. And as useful as these jacks are on their own, [Adam] stepped things up by using three of them to make a kinematic base, which is finely adjustable in three axes. It’s not quite a nanopositioning Stewart platform, but you could see how adding three more jacks and some actuators could make that happen.

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3D Printing Aids Metal Polishing

September 20, 2022 by Jenny List 9 Comments

While a machinist can put a beautiful finish on a piece of metal with their lathe or mill, to achieve the ultimate finish, a further set of polishing procedures are necessary. Successively finer abrasives are used in a process called lapping, which removes as far as possible any imperfections and leaves eventually a mirrored smoothness. It’s not without problems though, particularly at the edge of a piece it can result in rounded-off corners as the abrasive rubs over them. [Adam the machinist] has a solution, and he’s found it with a 3D printer.

To avoid the rounded edges, the solution involves fitting a piece of metal or wood flush with the surface to be lapped, such that the pressure doesn’t act upon the corner. This can be inconvenient, and the solution avoids it by 3D printing a custom piece that fits over the entire machined object providing a flat surface surrounding the edges. We see it being used with a demonstration piece that has three separate surfaces in the same plane to lap,something that would have been challenging without the 3D printed aid.

Lapping isn’t a process we see too often here. But it has cropped up as an extreme overclocking technique.

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A Vacuum Pick Up Tool For Not A Lot

September 18, 2022 by Jenny List 13 Comments

When working with grain-of-dust surface-mount components, one of the tools which makes a huge difference is a vacuum pickup pen. Instead of trying to move the part with tweezers and succeeding only in flicking it into the middle distance, a tiny rubber suction cup with a vacuum feed allows you to pick it up and place it exactly where it is required. Unfortunately, good vacuum pickup tools come at a price, and very cheap ones aren’t worth the expenditure.

This is where [TDG (Béla)]’s SMD vacuum pickup tool comes in. The problem with the cheap tools is only that their manual vacuum is ineffectual, they come with the required array of probes with the suction cups. The solution is to take a small vacuum pump with a low voltage motor and attach it with a 3D printed adapter to the business end of a cheap vacuum tool and make a useful tool the result.

There’s a short video of the tool in action that we’ve placed below the break. It’s a bit noisy, but it’s obvious that it performs well. Control is via an air hole in the side of the 3D print, place a finger over it and the full suction is directed to the tip. The result is simpler and cheaper than previous contenders in the budget vacuum pickup stakes.

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Mokeylaser: A DIY Laser Engraver That You Can Easily Build

September 14, 2022 by Dave Rowntree 25 Comments

[Mark aka Mokey] borrowed his friend’s open-frame laser engraver for a while, and found it somewhat lacking in features and a bit too pricey for what it was. Naturally, he thought he could do better (video, embedded below.) After a spot of modelling in Fusion 360, and some online shopping at the usual places, he had all the parts needed to construct an X-Y bot, and we reckon it looks like a pretty good starting point. [Mark] had a Sainsmart FL55 5.5W laser module kicking around, so that was dropped into the build, together with the usual Arduino plus CNC shield combo running GRBL.

[Mark] has provided the full F360 source (see the mokeylaser GitHub) and a comprehensive bill-of-materials, weighing in at about $400, and based upon the usual 2040 aluminium extrusions. This makes MokeyLaser a reasonable starting point for further development. Future plans include upgrading the controller to something a bit more modern (and 32-bits) as well as a more powerful laser (we do hope he’s got some proper laser glasses!) and adding air assist. In our experience, air assist will definitely improve matters, clearing out the smoke from the beam path and increasing the penetration of the laser significantly. We think there is no need for more optical power (and greater risk) for this application. [Mark] says in the video that he’s working on an additional build video, so maybe come by later and check that out?

Obviously, MokeyLaser is by no means the only such beast we’ve featured, here’s the engravinator for starters. For even more minimalism, we covered a build with some smart optics doing all the work. But what if you don’t happen to have a 5W laser module “lying around” then perhaps try a more natural heat source instead?

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If The Blade Sees Its Shadow, It’s Another 64th Of Accuracy

September 11, 2022 by Matthew Carlson 43 Comments

If you’ve bought a miter saw in the past few years, you might have noticed the LED “laser” that came with it. The goal was to show where on the piece the saw was going to cut. But over a year or two, you might have found the laser to have drifted or skewed into a crooked line. [Fisher] decided that his after-market laser wasn’t entirely accurate enough and added a shadow line instead. (Video, embedded below the break.)

The blade has a thickness (known as kerf), and with a laser to one side, you can only accurately cut on one side of the line. A shadow line works differently. By shining a line at the top of the blade, you get a mark where the blade will cut precisely. You can also see your marks as the laser doesn’t shine over them. Previously, [Fisher] had tried to use LED strips, but after a comment suggested it, he found a sewing light on a gooseneck. It worked great as a small compact light fitting the blade housing. After some quick modifications, hot glue, and duct tape, the light was installed, and the wires were routed while still allowing the saw its full range of motion.

The result is impressive, with a clear shadow on even darker hardwoods. Just the few test cuts he made seemed entirely accurate. Of course, you can always go deeper down the hole of accuracy and measurement. But overall, [Fisher] has a great little mod that speeds up his workflow more accurately. Continue reading “If The Blade Sees Its Shadow, It’s Another 64th Of Accuracy” →

Ask Hackaday: Stripping Wires With Lasers

September 8, 2022 by Al Williams 22 Comments

Most of us strip the insulation off wires using some form of metal blade or blades. You can get many tools that do that, but you can also get by with skillfully using a pair of cutters, a razor blade or — in a pinch — a steak knife. However, modern assembly lines have another option: laser stripping. Now that many people have reasonable laser cutters, we wonder if anyone is using laser strippers either from the surplus market or of the do-it-yourself variety?

We are always surprised that thermal strippers are so uncommon since they are decidedly low-tech. Two hot blades and a spring make up the heart of them. Sure, they are usually expensive new, but you can usually pick them up used for a song. The technology for lasers doesn’t seem very difficult, although using the blue lasers most people use in cutters may not be optimal for the purpose. This commercial product, for example, uses infrared, but if you have a CO₂ laser, that might be a possibility.

The technique has found use in large-scale production for a while. Of course, if you don’t care about potential mechanical damage, you can get automated stripping equipment with a big motor for a few hundred bucks.

We did find an old video about using a CO₂ laser to strip ribbon cable, but nothing lately. Of course, zapping insulation creates fumes, but so does lasering everything, so we don’t think that’s what’s stopping people from this approach.

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Custom Lathe Tool Cuts Complex Oil Grooves

September 8, 2022 by Anne Ogborn 41 Comments

Oil grooves are used to lubricate the inside of a bearing, and can come in many forms — from a single hole that takes a few drops of oil, to helical patterns that distribute it over the entire internal surface. The ideal arrangement is a looping figure eight pattern similar to an oscilloscope Lissajous figure, but cutting these is a nightmare. That is, unless you’ve got the proper tool.

We figure [Machine Mechanic] must need to cut a lot of them, as they spent quite a bit of time perfecting this custom lathe attachment to automate the process. Through an assortment of clever linkages and a rod-turned-crank that was welded together in-situ, the device converts the rotational motion of the lathe into a reciprocating action that moves the cutting tool in and out of the bearing. Incidentally the business end of this gadget started life out as a bolt, before it was turned down and had a piece of tool steel brazed onto the end.

With a little adjustment, it seems like this device could also be used to carve decorative patterns on the outside of the workpiece. But even if this is the only trick it can pull off, we’re still impressed. This is a clever hack for a very specialized machine shop operation that most would assume you’d need a four-axis CNC to pull off.

Lathes seem at first like rather single purpose machines, we’re always pleased to discover strange and wonderful things being done with them, like this seemingly impossible-to-turn piece, and this combo wire EDM and lathe.

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