NEW DESIGN For Anti-Backlash Acme Nuts!

[teebee]

Just another possible solution...
http://www.kerkmotion.com/learn/kerk...h-overview.asp

[sanjiv]

cant we make these slides in home work shop?
these manufacturers are all commercial
what about hobbists?

[lerman]

that they assume a constant pitch screw. A system with compliance (a spring) between the two nuts can automatically adjust for pitch variations. A system with a rigid connection between the two nuts must have enough play to permit the nut (pair) to fit at both the maximum and minimum pitches. This translates directly into backlash at the loosest points.

If we are using ground screws, this shouldn't be a problem. For cheap threaded rod this will be a problem.

A cheap, but laborious, approach might be to mechanically lap a length of threaded rod against a long nut using appropriate abrasive. This would cause the threaded rod to have a constant pitch that matched the pitch of the nut. Then the nut could be cut into two lengths and ridgidly connected with little clearance.

Ken

[gmc6711]

Moved

[ZipSnipe]

Hey Widgit, I was studying what you have made. On the third picture from the left, does the little circle piece have a threaded hole? It seems like it should. On the fourth picture it looks like its inserted into the bigger piece and its threaded but I can,t really tell by the pics you have posted. Anyway if it is threaded nice job! If its not threaded , please explain how that would work?

[widgitmaster]

Actually, this was an experiment that proved to be too costly, not very efficient, and I just lost interest in it!

The design was to have the 2nd nut slide in a bore, and have two 10-32 SHCS put tension on the pitch to remove the backlash on the thread!

This design does remove the backlash, and would probably work really good under normal conditions; however, as someone pointed out already, the pressure on the SHCS is to much. And yes, had I threaded the OD of the 2nd nut, and the ID of the main nut the concept would be flawless!

I just have too many projects going on, and need to make money to fund my very expensive new shop! You are welcome to use the concept and improve upon it!

Eric

[handlewanker]

Hi all, The method using a fixed back-up nut is too inflexible and will still have backlash, even if it's only a thou or two at first it will progressively get worse. I used the method as already stated with the spring between two nuts, in a housing. The housing is attached to the machine body with one nut captive. The other nut is pushed apart, by the spring, and prevented from rotating, just keeps it against the opposite flank. The spring must be strong enough to hold the drive force when reversing under load. It works beautifully on a centre lathe cross feed nut, no lost motion when single point screw-cutting and backing out. Also helps when parting off to prevent pull ins.
Ian.