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.
After securing a ball nut of the proper pitch and diameter, [Andy] looked for ways to shorten it without ruining it. Unfortunately, ball nuts are usually made of hardened steel, which tends to make the usual subtractive methods difficult. But when all else fails, you pull out the metal shop problem solver: the angle grinder. That had the benefit of shortening the nut while simultaneously annealing the steel around the cut, making it possible to face in the lathe. [Andy] put this happy accident to use twice in the build, and it’s a tip we’ll be filing away for a rainy day.
The whole modification process is presented in the video below, which includes testing the modified ball nut. It turned out pretty well, at least in terms of axial backlash. There are compromises, of course, but far fewer than we expected when the sparks started flying from that precision-machined ball nut.
I’ve always been very fond of the modding middle ground between DIY or Buy which tends to generate a lot more collective work and documentation than pure DIY projects or costly commercial solutions.
Nothing is a better exemple in my mind than the k40 laser machine, thats starts from a stamp engraver to become an amazingly capable machine for less than 600 bucks -mod parts included-.
I only needed mine for prototyping rather than production so I modified an RV portable compression fridge to use as a cooling system rather than pay 500$ + for a CW5000 which is more than the laser cutter itself
Love mod projects, keep them going HaD !
Nice followup, and I totally agree. The hardened steel is much more durable, and the relatively simple modification probably warrants the extra cost of a commercial version.
1204 ball screws are indeed the most cost effective. Prices start around EUR20 directly from Ali but they are not “all the same”. there are (significant?) quality differences between the “brandless” types.
Both 10mm and 8mm is also easy to find, search for FSK0802 FSK1002 FSK1004 (I.e. diameter and pitch) but prices of those are almost double of the SFU1204. Maybe there are also less “fakes” for these less common combinations, and quality may be better. I guess that aliexpress has a bigger assortment in different sizes then Ebay / Amazon and such.
With SFK0801 you also get a quite fine pitch, with tiny balls and smaller diameter nuts
I don’t care how tempting the title is I will not make an off colour joke. Nice hack though.
Younger me: Let’s fabricate it all! This will be fulfilling and fun.
Older me: I’m getting too old for this and I have cash, I’ll buy the proper components.
If you first properly learn the rules, you are then allowed to break them
As a knife make, I smile at the idea of ‘hardened steel.” Just aneal it, grind it, them harden it again. Probably $20 USD for a nut. $40 USD for a sword.