- Joined
- Nov 24, 2017
- Messages
- 64
Just in case others are having problems with their 3 Jaw Chuck this is what I did to correct the majority of my run out.
My 3 Jaw chuck was next to useless with so much run out I found I was using the 4 Jaw as a preference.
I didn't have a dial indicator so I went out and found myself a cheapish one. (Seems to work just fine)
The OD of the chuck it self was running out about .006" but if I put a piece of bright round bar in the chuck sticking out about 4" it was so far out I didn't even try to measure it.
With nothing to loose I took the chuck off and marked the position of things with a centre punch for re assembly.
I put the dial indicator on the OD of the spindle nose and the run out was under .001". I think this was mostly surface imperfections. With the spindle stopped If I leaned on it lightly pushing back or forwards the needle moved about .001" so I figure the free play in the bearings isn't too bad and I should leave well enough alone. (Babbitt Bearings)
So I pulled the chuck apart and again there was all sorts of crap in there but nothing broken or missing.
After a good clean up, a light oil and some careful reassembly, the parts all move nice and free now.
Before I reattached the backing plate I decided to put that on the spindle on it's own.
The OD ran out by about .003" and seeing as how that doesn't do anything much I gave it a lick and cleaned it up as a reference to ensure it can be removed and remounted consistently. After that I put the dial on the flat face where the chuck sits (90 deg to bed way). This too was running out about .005". I also faced this off being careful not to touch the diameter that actually centres the chuck at this stage. The corner is undercut a fair bit which made leaving the OD alone easy.
After a little touch up on all the champers I remounted the chuck. I put my dial on the OD of the chuck and it now runs out about .001"
I stuck a nice bit of bright bar in the jaws and it is the same about .001". Sticking out about 4" it is the same.
I can't believe how successful this process was. I could have faced off the existing step which centres the chuck as there is enough meat on the mounting plate to have another go but I don't think I will achieve a much better result.
I also offset the Jaws one position. (1->2, 2->3, and 3>1). I'm not sure if this made any difference but once it was fixed I stopped messing with it
Hope this inspires others to dismantle and clean out their old 3 Jaw.
David
My 3 Jaw chuck was next to useless with so much run out I found I was using the 4 Jaw as a preference.
I didn't have a dial indicator so I went out and found myself a cheapish one. (Seems to work just fine)
The OD of the chuck it self was running out about .006" but if I put a piece of bright round bar in the chuck sticking out about 4" it was so far out I didn't even try to measure it.
With nothing to loose I took the chuck off and marked the position of things with a centre punch for re assembly.
I put the dial indicator on the OD of the spindle nose and the run out was under .001". I think this was mostly surface imperfections. With the spindle stopped If I leaned on it lightly pushing back or forwards the needle moved about .001" so I figure the free play in the bearings isn't too bad and I should leave well enough alone. (Babbitt Bearings)
So I pulled the chuck apart and again there was all sorts of crap in there but nothing broken or missing.
After a good clean up, a light oil and some careful reassembly, the parts all move nice and free now.
Before I reattached the backing plate I decided to put that on the spindle on it's own.
The OD ran out by about .003" and seeing as how that doesn't do anything much I gave it a lick and cleaned it up as a reference to ensure it can be removed and remounted consistently. After that I put the dial on the flat face where the chuck sits (90 deg to bed way). This too was running out about .005". I also faced this off being careful not to touch the diameter that actually centres the chuck at this stage. The corner is undercut a fair bit which made leaving the OD alone easy.
After a little touch up on all the champers I remounted the chuck. I put my dial on the OD of the chuck and it now runs out about .001"
I stuck a nice bit of bright bar in the jaws and it is the same about .001". Sticking out about 4" it is the same.
I can't believe how successful this process was. I could have faced off the existing step which centres the chuck as there is enough meat on the mounting plate to have another go but I don't think I will achieve a much better result.
I also offset the Jaws one position. (1->2, 2->3, and 3>1). I'm not sure if this made any difference but once it was fixed I stopped messing with it
Hope this inspires others to dismantle and clean out their old 3 Jaw.
David