Anti-backlash nut

[mikeschn]

Does anyone make a commercial anti-backlash nut for off the shelf 1/4-20 threaded rod? Got a URL?

Otherwise, does anyone have a good idea for a homemade anti-backlash nut?

Thanks,

Mike...

[anoel]

Kerk Motion makes several different types in a .05" lead.

http://www.kerkmotion.com

Search CNCZone for this subject there are several homeade anti-backlash nut designs. That's probably easier than relisting them here in this thread.

[NeoMoses]

I don't think I've seen a commercial anti-backlash nut for threaded rod. If you do some searching, you'll find some member's anti-backlash nuts on here. Most of the time it consists of 2 nuts loaded against each other to remove the backlash. Delrin works well on threaded rod and acme rod.

[anoel]

Sorry I assumed that it was Acme thread since he siad 1/2-20 (most 1/2" v thread is 13 turn.

Yeah the Kerkmotion link is only for acme.

[mikeschn]

Opps, I definitely meant 1/4-20 threaded rod. (I fat fingered it up there...) I could buy a 1/4" leadscrew with anti-backlash nut here... http://www.smallparts.com/products/descriptions/lsx.cfm but I am looking at $75 for a 36" assembly... and I need 3 assemblies.

I am currently looking at ways to keep 2 nuts spreadapart by a spring. I'll keep you posted though!

Mike...

[ger21]

Look here at the bottom of the page:

http://www.cnconabudget.com/stuff.html

Cut a slot and put an o-ring around it to keep it tight.

Gerry

[mikeschn]

Hey Gerry,

That is indeed a simple solution. While you were posting that, I was over here trying to keep two nuts separated by a spring.
Maybe I'm all wet, but tell me what you think anyways.

Basically you thread on your two nuts and your spring, and adjust it to the desired tightness. Then you position it next to your gantry wall, and slide a capture plate over it. Last you have to fasten one of the nuts to the capture plate to keep it from moving... perhaps with a set screw.

It doesn't seem quite as simple as your idea, but I'll bet it works!

Mike...

P.S. I know the capture plate looks really thick... but it's only 3/4" thk.

[mikeschn]

Okay, here's another pass...

You make one flanged nut out of nylon or delrin. Really, this is just a 7/32 thk plate with a threaded hole in it. You thread on a spring and another nut. When your desired tension is reached, you slide the nut into the hex in the gantry wall, and bolt on the delrin nut.
Your thoughts?

Mike...

[anoel]

For 1/4"-20 just simply tap a Delrin block with a 1/4" -20 tap and put a slit in it and use a screw to squeeze the backlash out. It's very easy to get the lash out of a 1/4-20 screw.

[ger21]

You might not have enough adjustment that way.

Gerry

[Hobbiest]

Is this your first machine? Just tap a piece of delrin, UHMW, or doubled thickness of cutting board and get your machine working. You can always change to an AB design later. If you are really set on AB nut, Tap two 3/4" by 1 1/2" by 1/2" pieces, bore a hole on either side of the tapped hole in one piece, about 1/4" deep to accept a 10-32 machine screw. Drill and tap coresponding holes in the other piece. Thread the two of them onto your screw, then insert two machine screws and tighten until backlash is eliminated. Affix one of the pieces to you gantry, etc and get rolling! the machine screws only need to be long enough to spread the two pieces apart by .20" (that is right...right...20tpi, one thread is .20"...right?)

[chuckknigh]

This is what I did. I started out with a design similar to yours, and kept redesigning it till it was simple. My final design was SIMPLE!

Basically I made a 2 part nut out of a cutting board, and cut a slit in it. I "flex" the nut such that the two halves come closer together, and squeeze the threads.

Instructions. Take a block of plastic...I used an unidentified waxy plastic cutting board that I bought at Goodwill. Drill 2 holes in it, parallel to each other. Tap both holes, all the way through.

Now, cut a slit across the path of the holes, almost dividing the nut in half...but leave it attached. Drill out half of one of the holes, so that the screw thread has nothing to grip onto. Insert a bolt into that half, and tighten it down. You'll notice it pulls the two halves of the nut, together.

The other hole is your "drive nut." The "squeezing" of the two halves, together, very effectively takes out the backlash...and it remains easily adjustable for wear.

Works great, and it's easy to mount!

-- Chuck Knight