How to eliminate backlash ?

[Ashish B]

Hi,

On my CNC Mill, I am experiencing positioning errors. I think that there are some BACKLASH issues associated with it.

I searched CNCZONE.COM for posts related to backlash. I really admire that all the posts are wonderful and really provide a indepth understanding of the BACKLASH. Also i can see some posts mentioning about the assembling the nut over the lead screw.
But to be frank, I can't understand those assembling issues and cannot do nut adjustment. I cannot do that because i am a root level operator.

Hence i request that please guide me to a simple solution to get rid of the backlash problems ?

Thanks
Ashish

[78nova]

It is helpful if you use a test indicator to measure how much backlash you have in each axis, in each direction. If it is minor, you can just make sure to keep the ballsrew going in the same direction each time you position the tool to the workpiece. In our situation, our horizontal mill has a tool changer and it has to go down in " Y " axis, ( minus ) and over in " X " axis ( minus ) after each tool change to position to the work piece. If we have critical positions to hold, we just add a jog motion Y +, X +, then Y -, X -, to keep the ballscrew alway positioning from the same direction to take up any backlash.

I know this is not a fixall but it helps if your backlash problem is of a small amount.

[Al_The_Man]

Hence i request that please guide me to a simple solution to get rid of the backlash problems ?

Ashish[/COLOR][/COLOR]

The details I made in your other post should help.
You have to identify where the backlash is of course, with a direct driven B.S. there is only a couple of places where it can be, either in the coupling or the B.S. nut, many precision B.S.'s have either preloaded nuts that self tension the pre-load, or have an adjustable pre-load.
If you do not have pre-loaded nut on the B.S., this could be where your B.L. is.
Al.

[Ashish B]

Yes, I will check in that style & let you know asap.

Thanks
Ashish

[Ashish B]

Hi,

I performed BACKLASH TRIALS as per your instructions. It goes as follows -

In X axis -
I touched a part by using plunger dial & jogged untill dial showed 0 reading.
Than i retracted back by 0.04 mm, but the dial pointer was retracted by 0.01 mm only.
So, is it a backlash error of 0.030 mm ?

In Y axis -
I touched a part by using plunger dial & jogged untill dial showed 0 reading.
Than i retracted back by 0.001mm, but the dial pointer was retracted by 0.020 mm...
So, is it a wrong backlash setting?

Also, i checked backlash error on my CNC turning (which is brand new...i purchased it on 20th august)... But backlash error was also in existence on that machine..

How to deal with backlash & whats the correct setting ?

Thanks
Ashish