Although my question is not an electronics question, it is related to an electronics project that I am planning. The project will use some 5/8 12TPI threaded rod as part of a linear positioner, and may need anti backlash nuts. I have looked on the web and found some information, but I wonder if anyone here has hands-on experience making and/or using anti backlash nuts on threaded rod. Thanks.

 

We used them on an engraving table we made in the mid 1980's. The table was about 19" x 19" and used Superior Electric stepper motors direct coupled to lead screws with an ACME thread. The nuts were easy to install and did a fine job.

 

 

From what he's done there, I don't see the need for the adjustment screws. Seems to me you could get the same effect by tightening two delrin (or walmart cutting board) nuts against each other and then fastening them together. Actually by going that route, you achieve the coveted "spring" action by placing a split lock washer between the two nuts.

 

From what he's done there, I don't see the need for the adjustment screws. Seems to me you could get the same effect by tightening two delrin (or walmart cutting board) nuts against each other and then fastening them together. Actually by going that route, you achieve the coveted "spring" action by placing a split lock washer between the two nuts.

It looks like he may have originally planned to use some sort of compression springs between the two pieces of Delrin, but then decided they weren't needed. Instead of pushing the nuts apart to force contact with both sides of the rod threads, now he's pulling them together. Do you buy his explanation that the use of Delrin reduces the wear? I can see how it reduces the wear on the rod, but what about the wear on the Delrin?

 

It looks like he may have originally planned to use some sort of compression springs between the two pieces of Delrin, but then decided they weren't needed. Instead of pushing the nuts apart to force contact with both sides of the rod threads, now he's pulling them together. Do you buy his explanation that the use of Delrin reduces the wear? I can see how it reduces the wear on the rod, but what about the wear on the Delrin?

That cutting board material is not delrin actually, but likely UHMWPE. That stuff is almost impervious to wear, which is why it's used as cutting board material. But it is not particularly strong. I would expect it to be relatively easy to rip the threads out of it. I believe him that in his application it works just fine, but I imagine his application cannot be that demanding or else it would fail. If you aren't going to be putting much load on it, should be fine for you too.

 

The 'real' Delrin bushing replacements are much cheaper than replacing a slightly worn lead-screw. We use a huge assortment of high precision tracks, all with anti-backlash nuts of some kind. If kept very clean the resin will self-align to the screw pattern quickly as long as it's uniformly worn.

http://plastics.dupont.com/plastics/pdflit/europe/design/L12565_7.pdf

 

I think I will try making some anti-backlash nuts similar to the ones in the video, but using compression spring(s) to keep tension between the nuts...maybe a valve spring?

 

I recently bought a Turnigy Fabrikator 3d printer and the z axis screw has an anti-backlash system, described quite well in the assembly instructions and I think there's a video on the HobbyKing website about it too. see https://www.hobbyking.co.uk/hobbyking/store/uploads/PRM0282_3D_printer_manual.pdf it might help or give you some ideas.

 

There's some interesting stuff here, but it's pricey (for a tightwad like me.)

 

Good luck with the SAE threaded rod... It sucks for anything "smooth/precision"...
Go ACME at the very least

Plenty of cheap ballscrews, etc... on ebay too from China.. I'd use them in a heartbeat over standard threaded rod..

 

I would second the Ballscrew idea if you can find an economical source, although in that size (5/8") will not be easy.
There are rolled B.S. which usually posses some backlash, precision ground with pre-loaded ball nut is the ideal, but gets costly.
The most economical at least cost that I have used is Hiwin from Taiwan.
Max.