ball screw

13 Articles

Ball Nut Modification Charts A Middle Course Between Building And Buying

December 29, 2024 by 7 Comments

A lot of the projects we feature here on Hackaday engender the classic “build versus buy” argument. We’ve always been puzzled by that; if anyone can appreciate the sheer joy of making something rather than buying it, it should be our readers. But there’s something to be said for buying the stuff you can buy and concentrating your effort on the bespoke aspects of the project. It’s perhaps not as exciting, but needs must, oftentimes.

Let’s not forget there’s a third way though, which [Andy] explores with this ball nut modification project. Keen-eyed readers will recall [Andy]’s recent scratch-built ball screw build, in service of some top-secret, hush-hush project related to world domination and total subjugation of humanity. His homebrew efforts in this regard were a great lesson in how to machine a complex mechanism to work in a constrained space. Still, it left folks wondering why he’d go to all the trouble when he could have just trimmed an off-the-shelf part down to size. So, he decided to give that a try.

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Rolling Your Own Ball Screws

December 4, 2024 by 24 Comments

We’ve got mixed feelings about a new video from [AndysMachines] that details how he makes custom ball screws. On the one hand, there’s almost zero chance that we’ll ever have an opportunity to put this information to practical use. But on the other hand, the video gives a fantastic look at the inner workings and design considerations for ball screws, which is worth the price of admission alone

The story behind these ball screws is that [Andy] is apparently in cahoots with SkyNet and is building a T-800 Terminator of his own. Whatever, we don’t judge, but the build requires a short-throw linear drive mechanism that can be back-driven, specs that argue for a ball screw. [Andy] goes through the challenges of building such a thing, which mainly involve creating threads with a deep profile and wide pitch. The screw itself wasn’t too hard to cut, although there were some interesting practical details in the thread profile that we’d never heard of before.

The mating nut was another. Rather than try to cut deep internal threads, [Andy] took a sort of “open-face sandwich” approach, creating half-nuts in a single piece of brass using a CNC machine and a ball-nose mill. The threads were completed by cutting the two halves apart and bolting them together — very clever! [Andy] also showed how the balls recirculate in the nut through channels cut into one of the half-nuts.

Whether the results were worth the effort is up to [Andy], but we were just glad to be along for the ride. And if you want a little more detail on lead screws and ball screws, we’ve got just the article for that.

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Improving Cheap Ball Screws

February 22, 2021 by 22 Comments

Most 3D printers use leadscrews for at least one axis. These are simple devices that are essentially a steel screw thread and a brass nut that travels on it. However, for maximum precision, you’d like to use a ball screw. These are usually very expensive but have many advantages over a leadscrew. [MirageC] found cheaper ball screws but, since they were inexpensive, they had certain limitations. He designed a simple device that improves the performance of these cheap ball screws.

Superficially, a ball screw looks like a leadscrew with an odd-looking thread. However, the nut is very different. Inside the nut are ball bearings that fit in the grooves and allows the nut to spin around with much less friction. A special path collects the ball bearings and recirculates them to the other side of the nut. In general, ball screws are very durable, can handle higher loads and higher speeds, and require less maintenance. Unlike leadscrews, they are more expensive and are usually quite rigid. They are also a bit noisier, though.

Ball screws are rated C0 to C10 precision where C10 is the least accurate and the price goes up — way up — with accuracy. [MirageC] shows how cheaper ball screws can be rolled instead of precision ground. These screws are cheaper and harder, but exhibit more runout than a precision screw.

This runout caused wobble during 3D printing that was immediately obvious on the prints. Using a machinist’s dial gauge, [MirageC] found the screws were not straight at all and that even a relatively poor C7 ball screw would be more precise.

The solution? A clever arrangement of 3D printed parts. ball bearings, and magnets. The device allows the nut to move laterally without transmitting it to the print bed. It is a clever design and seems to work well.

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Plastic Strips Protect Ball Screws On This Homebrew CNC Router

October 26, 2020 by 17 Comments

It’s a fact of life for CNC router owners — swarf. Whether it’s the fine dust from a sheet of MDF or nice fat chips from a piece of aluminum, the debris your tool creates gets everywhere. You can try to control it at its source, but swarf always finds a way to escape and cause problems.

Unwilling to deal with the accumulation of chips in the expensive ball screws of his homemade CNC router, [Nikodem Bartnik] took matters into his own hands and created these DIY telescopic ball screw covers. Yes, commercial ball screw covers are available, but they are targeted at professional machines, and so are not only too large for a homebrew machine like his but also priced for pro budgets. So [Nikodem] recreated their basic design: strips of thin material wound into a tight spring that forms a tube that can extend and retract. The first prototypes were from paper, which worked but proved to have too much friction. Version 2 was made from sheets of polyester film, slippery enough to get the job done and as a bonus, transparent. They look pretty sharp, and as you can see in the video below, seem to perform well.

It’s nice to see a build progress to the point where details like this can be addressed. We’ve been following [Nikodem]’s CNC build for years now, and it really has come a long way.

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Steel Tubes And Ground Plates Form The Skeleton Of This DIY Vertical CNC Mill

November 27, 2019 by 29 Comments

If you’re going to do it yourself, you might as well outdo yourself. That seems to be the thinking behind this scratch-built CNC mill, and it’s only just getting started.

According to [Kris Temmerman], the build will cost about $10,000 by the time he’s done. So it’s not cheap, and a personal CNC from Tormach can be had for less, but that’s missing the point entirely. [Kris] built most of the structural elements for the vertical mill from cheap, readily available steel tubing, of the kind used for support columns in commercial buildings. Mounted to those are thick, precision-ground steel plates, which eat up a fair fraction of the budget. Those in turn hold 35 mm linear bearings and ball screws for the three axes, each powered by a beefy servo. The spindle is a BT30 with a power drawbar, belt-driven by an external motor that [Kris] doesn’t share the specs on, but judging from the way it flings chips during the test cut in the video below, we’d say it’s pretty powerful.

There’s still plenty to do, not least of which is stiffening the column; perhaps filling it with epoxy granite would do the trick? But it sure looks like [Kris] is building a winner here, and if he keeps the level of craftsmanship up going forward, he’ll have a top-quality machine on his hands.

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Mechanisms: Lead Screws And Ball Screws

November 13, 2018 by 52 Comments

Translating rotary motion to linear motion is a basic part of mechatronic design. Take a look at the nearest 3D-printer or CNC router — at least the Cartesian variety — and you’ll see some mechanism that converts the rotation of the the motor shafts into the smooth linear motion needed for each axis.

Hobby-grade machines are as likely as not to use pulleys and timing belts to achieve this translation, and that generally meets the needs of the machine. But in some machines, the stretchiness of a belt won’t cut it, and the designer may turn to some variety of screw drive to do the job.

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Homebrew Linear Actuators Put The Moves On This Motion Simulator

October 4, 2018 by 32 Comments

Breaking into the world of auto racing is easy. Step 1: Buy an expensive car. Step 2: Learn how to drive it without crashing. If you’re stuck at step 1, and things aren’t looking great for step 2 either, you might want to consider going with a virtual Porsche or Ferrari and spending your evenings driving virtual laps rather than real ones.

The trouble is, that can get a bit boring after a while, which is what this DIY motion simulator platform is meant to address. In a long series of posts with a load of build details, [pmvcda] goes through what he’s come up with so far on this work in progress. He’s building a Stewart platform, of the type we’ve seen before but on a much grander scale. This one will be large enough to hold a race car cockpit mockup, which explains the welded aluminum frame. We were most interested in the six custom-made linear actuators, though. Aluminum extrusions form the frame holding BLDC motor, and guide the nut of a long ball screw. There are a bunch of 3D-printed parts in the actuators, each of which is anchored to the frame and to the platform by simple universal joints. The actuators are a little on the loud side, but they’re fast and powerful, and they’ve got a great industrial look.

If car racing is not your thing and you’d rather build a full-motion flight simulator, here’s one that also uses DIY actuators.

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