backlash

[comet]

Hi,
I want to try and eliminate the backlash in my servo'ed triac.
the machine is hardly used but has approx 0.003" of back lash in each axis.
Is there an "official" way of tightening this up,or is this the correct working clearence? I was just going to turn one ball nut against its partner to try and do it.

[Triac whizz]

if it's a Fanuc control you can do it in the parameters, I didn't think there was 2 ball nuts

[Triac whizz]

so there is (2 ball nuts) bit of a sod to get at though...

[comet]

no,
its mach 3, you can set up backlash comp but thats only really any use for point to piont drilling,as a milling cutter will draw the table in espetially when climb milling

[Triac whizz]

looks like you'll have to play with yer nuts

a lot of people would be very happy with only 3 thou backlash

[Steve]

Have you checked the bearings that fix the end of the ballscrew? I am not sure what you should expect from the screws but I would expect it to be tenths. Do you have backlash in all axes?

I think the double nut was only fitted to the Z axis and then only on later models.

Are the drive belts tight?

[comet]

its definatly double nuts all round and its a 1986 model.
Ill check the bearings,but Im 99% sure there ok.
Belts are just right,its the same on every axis.
Anybody got an idea as how I can check the shaft bearings for endfloat?
Isuppose I could put a mag clock on the table/pulley and try and move the table.

[Denford Admin]

End float is usually a bit un predictable - you can get different results depending on the speed you change direction / accel / decel etc..

I think the best way is to get hold of it and push / pull it while watching the clock. A big rubber hammer may also help - make sure servos are on and that you aren't back winding the screw