Can this chuck be improved?

mattthemuppet2 said:
I'm not sure if I missed it, but did you check the runout on the face of the backplate when it is mounted on the spindle? It's got to be due to either backplate mounting or if that's good, needing a skim cut to get the chuck to run true. No way a 3 jaw should be running out that much.
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No I have not done that. I will get to that next. Disassembly of the chuck will take a little time to get to now, If I understand you correctly, if a problem exists I will have to take a light facing cut on the back plate at the pin position it is now requiring a light tap to loosen the chuck for removal. Thanks for the input and help.
Ray
 
Ray, when you are turning the cams to pull the backplate tight to the spindle how much torque do you have to put on the cams? Do you feel an abrupt stop in the cam when tightening? .014 runout seems like a lot to me too. Before making any cut on the backplate it should be clear that the back plate is fully seated to the spindle.
 
Tozguy, I have been putting quite a bit (estimate 20 foot pounds) all I can put on a 6" rod in the wrench. After finding where the spot where a light tap is needed to loosen the chuck and the high spots on the pin holes I don't think the excessive torque will be required, in fact I cannot get a 0.006" feeler gage to go in anywhere now.
Matthemuppet,, Being a one person show I changed my priorities and have checked the run out on the faceplate, 0.009" runout. I think my next move is grinding a 1/2" HSS bit with a small round end and try to take just enough off to get a cut mark full circle. I am thinking two passes at 0.005". I will check for clearance before cutting with a light behind the spindle and faceplate.
Have a good day!
Ray
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That still seems like a lot of runout (.009'') even for a no name backplate. Also, a thinner feeler gauge (.001 or .0015) would be a better test. The light test is better still but even then I would want to be able to feel when torquing cams with the wrench that the backplate 'stops' against the spindle.
The work you have done so far has reduced the runout considerably but there might still be a bit left to do before starting to true the face on the backplate.
 
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I hadn't really concentrated on when the chuck hit the back plate but I have felt it stop moving when turning the cam locks. The gap when the chuck is pulled up with a cam lock can be seen to close. I tighten each cam lock by rotating the chuck to bring each loose cam lock near top dead center, tighten that one to "snug", then rotate and tighten all a second time. It takes three rotations to get the chuck firmly mounted.
One thing I haven't mentioned is there is a ring around each cam lock pin that just disappear into the backing plate when the pins are at the right depth. I have checked the distance from the end of the pin to the back of the face plate, they are all the same distance. I am going to the shop now to check for gaps.
 
sounds like you're heading down the right road. As others have suggested you need to fix the fit of the backplate to the spindle first, then check runout of the backplate face. Once you're at that step, blue (or sharpie) the face of the backplate, then take off only enough to get rid of the colour. Make sure any edges and holes are deburred, then check for runout again.

Went through this with my lathe a little while ago but started with headstock alignment first. It all made a big difference that's for sure.
 
Seems like I haven't left square one yet. Found a 0.004" bump beside one of the cam lock holes took a 8" file to it and now 220 grit emery cloth, down to 0.002" now. It is a localized bump-less than 1/2" long. The bump is keeping the backplate from coming flush with the spindle faceplate. I have a Craftsman grinder but am a little nervous about the bearings in it being to loose. More on that tomorrow. Sure appreciate the help, thanks
Have a good day
Ray
 
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