Hello everybody !!
Grinding the Jaws on a 3 Jaw Chuck
I think this is a new chuck that could have been adjusted on the back plate. I have seen this so many times when a new chuck is fitted to a lathe that it doesn’t run true The chuck needs to have a bit of adjustment on the back plate or you will never get a new chuck to run true. A friend only a month back bought a new chuck for a Myford lathe and explained it was no good. I removed the chuck from the backplate re machined the back plate used a test bar and clocked the new chuck true to lathe axis. Unfortunately the chuck in the video will never be true as the reverse jaws will also run out and the jaws ground will not be able to hold anything internally as these will not be true to the lathes centre line either. Very expensive mistake I am afraid.
The Home Engineer
I had thought of that too, and it looks like there are 3 (?) bolts holding the backing plate to the chuck which would have allowed adjustment.
However, the chuck body "appears" to be running true..with no discernible run-out; if it did have, it would've been vibrating.
He should have checked that first.
I don't know why he thinks TIR of .002 is sufficient.
I do understand that we all do things differently.
But I am also curious why the front of the jaws are ground deeper than the rest of the jaw. The ring made for the second operation could have been slipped over the Internal jaws and the jaws ground in one pass which would be the normal way to true an old worn chuck. (Of course i still think checking that the chuck could not be run concentric on the back plate first) This chuck would have been in the region of £150/£250 and I do feel a bit sorry for the guy as I am sure he did this with the best intention but with out thinking the whole job through. There is plenty of experience people who would be more than happy to share their knowledge and experience on how they would have approached this task before sending in the grinder.
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