Anti-backlash bearings for acme screws

Hi Guys,
I take it you are referring to END Float on the shaft and not backlash on the thread.
This can be eliminated using a ball bearing on either end of the screw, shimmed to be a close fit for length and just "lightly" tensioned with a nyloc nut on the floating end of the screw, opposite the motor.
You also can have both bearings back to back with each other at the motor end with a small shim between them to allow for lightly compressing the bearings together to eliminate the end float, but remember, you only need a light pressure on them just to eliminate the float otherwise you will get bearing heating which will increase the pre-load and make things tighter than they should be which will cause drag and premature failure of the bearings or loss of steps on your motors etc
Have fun with the build.
Rich.

On my mill I used a pair of ordinary angular contact bearings and sprung them using the end of an old square section air rifle spring crushed close to solid.

It's all rolling contact so it spins freely on the handle, the spring compensates for temperature change and it doesn't move one jot unless I make a horrible mistake.

If your frame can take the strain, one bearing at either end is definately best because it keeps the whole thing in tension. I used two at one end but plan to rework it with die springs when I get the time because it works so well and I have become anal about the .003" backlash. I'm thinking 2 ball nuts and another spring.

The cheapest place I found for the bearings was VXB Bearings on eBay, cheapest despite the trans-pond shipping.

We currently have the bearings for sale on ebay, just under £4 will get you a pack of 8. :-)

Ebay Link: http://stores.ebay.co.uk/MYCNCUK

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Originally Posted by Robin Hewitt

On my mill I used a pair of ordinary angular contact bearings and sprung them using the end of an old square section air rifle spring crushed close to solid.

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Any chance you have a pic of that setup for us to see ?

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Originally Posted by CNCUK

Any chance you have a pic of that setup for us to see ?

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It's rather enclosed, no seals on the bearings, had to bury it a bit.

I would take a pic but I just moved the workshop out of the garage up on to the industrial estate :D

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Originally Posted by Robin Hewitt

It's rather enclosed, no seals on the bearings, had to bury it a bit.

I would take a pic but I just moved the workshop out of the garage up on to the industrial estate :D

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Ok Robin some other time maybe, i think we all know what it is like to have a work shop with space!

Cheers Mate.

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Originally Posted by CNCUK

Ok Robin some other time maybe, i think we all know what it is like to have a work shop with space!

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I had plenty of room but the big benefit is not worrrying about her indoors moaning about metal cuttings walked in to the house. I forgot to tell her that swarf is death to carpets so I was actually getting away with it :D

Also I can now play at CNC plasma cutting without sooting up her car (double garage) and I have bought this book on how to melt cast iron by burning old engine oil. Not the sort of thing I want to do under he watchful eye in case there's a spillage.

lmao, i'v got a small work shop but still end up with piles of stuff in the house! Would she not go for the vented body kits the boy racers go for then? :D

Try this link...

http://www.artfulbodgermetalcasting.com/3.html

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Originally Posted by Kip

Sounds like fun! I'm intending to build a cupola over the winter using some Babington burners....I have the balls already! Babington burner

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Hi kip, what is a cupola ?