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rhurt
03-24-2007, 11:29 PM
Does anyone know how to adjust the backlash on a Delta 40 using the setup
screen ,and using RX AND RY values ? I know you're suppose to measure the backlash with an indicator and put the values in the RX AND RY ,but Im up to .0066 on the x axis and it doesn't seem to make much differance, when I
cut a cirlcle Im about .003 to .004 of round. ???

redcobra
03-25-2007, 12:23 PM
Tool pressure will cause the backlash to not be there because the cnc doesn't know that it moved

brianaldrich
03-25-2007, 08:19 PM
ajust your gib and check your ballscrew bearings and ballscrew nut thats way to much to comp out

dogstar
04-15-2007, 02:02 AM
re Backlash on Delta 40

I have a Delta 20, so this info may not apply:

An experienced tech did this:
1) Setup a reliable sensitive indicator on the middle of your table, with tip against spindle, no tool.
2) Move table ONLY in X axis...say ~.100 to .150" ...to overcome sticktion.
3) zero-out indicator & now move another .1000", using jog.
4) Immed. move back same amount, .1000"
5) Dial should return to '0' in an ideal world.
6) To adjust go to mode select 5, setup, page 2, Reversal Comp
7) Type in RX +0.0025 (say you were out -.0025) This compensates for this error in X.
Try step 2 to 5 again. Dial should reurn to '0' now. If not, adjust RX again.
8) If it does zero-out now try jogging the other way. It should still zero-out nicely.

Now do the same test for the Y axis & adjust RY accordingly....then, you guessed it.... adjust the RZ. (diiffcult to attach the magnetic-base I found!) & adjust. If you're fussy do ALL THREE AXES again, this time with the indicator near the travel limit of the table (& then a THIRD time at the opposite end)....you'll prob'ly get different numbers because of the wear in the middle of the ball screw vs. the ends. If you get virtually the SAME values....this is a good thing. Means the ball-screw is not worn unevenly--OR--it is worn-out but quite evenly.

Jake told me when any error here gets over 0.001" to 0.0015 then adjust the end bearings & ballscrew nut backlash....a big job. If this doesn't help then Jake said the mill's accuracy is gone....time for a new machine.
Hope this helps.