Backlash Or A Different Problem ?

looks like you have straight gibs..they will only adjust side to side...wont do anything about lift if there is any space under the clamps ..(arrow)...with angled one they are locked in pretty much, when the gibs are tight just right they cant go up

gibs.jpg
 
Okay. I have taken the table off about 8 times to re adjust the lead screw mounting hardware. I have gotten it to bear .5 thousands or jump when changing directions. What should I be shooting for as far as tolerance.

image.jpeg image.jpeg
 
I will take out my .0001 last work indicator later and get serious about the tolerance. Any tips would be great. And thanks for all your replies. You have greatly helped me out here.
Thanks
Dylan
 
The only way I can see to get the lead screw perfect or close to perfect would be to loosen the lead screw casing while it's taken apart. And put it all back to get her loose and make a funny shape hex wrench to tighten the lead screw nut once the lead screw and handle have been put back on. That way it can align itself to the table and ways freely and then be tightene into place with out any tension torqueing the table in the wrong direction. The lead screw nuts casting is pretty rough and there is no way to square it to the table with out the lead screw running my through it to bring it square to the ways. Or maybe I should just leave it at .005
Thanks
Dylan
 
Dylan,
Much depends on your machine expectations and your personal tolerance.
For me and my 100 year old Cincinnati mill that would be great!
-brino
 
I dunno. 0.005 is quite a bit in my book, I would expect 0.000 lift. If I understand correctly, the threaded hole in the nut does not line up with the base, thus putting the lead screw in a bind when the nut base is tightened down. It seems to me that some filing and possibly some shims might be in order.
 
JimDawson said:
I dunno. 0.005 is quite a bit in my book
Click to expand...

Oooops! I missed a zero.......sorry.:confused:
You were talking ten-thousandths in post #24 and then thousandths in post #25.
I'd like better than 5 thousands on mine too!
-brino
 
Yep. The threaded helped dosent line up and can't be squared because of casting defects. I have just assembled and disassembled the table a bunch of times making guesses at fine adjustments to the lead screw nut. The lead screw nut can be moved about 1/8" in a few directions when the 2 hex bolts are loosened. I put the table back together with those 2 hex bolts loosened and their was no jump at all because the lead nut could align itself correctly with the ways. I thought that I could then dissemble the table carefully and then tighten the hex bolts in correct place when the table was removed. However in order to get the table off the lead screw must be completely removed and no matter how carefully it is done the nut and housing wiggles befor I can get to the hex bolts and tighten them. I am not sure what the tool on going to make will look like but it will tighten the hex bolts once the table has been put back together. Also is there any reason I couldn't keep the hex bolts a bit loose so that it wouldn't torque the lead screw ? When the table was set up like that is was very smooth but i did not try to mill anything with that set up so I can't know if it would be acceptable.
 
I think if you left the bolts loose that it would introduce a lot of backlash and probably chatter into the system. There is a big hole under the table, is it not possible to get to the bolts from there?
 
You must log in or register to reply here.
Back
Top