In total shock over my Shars 3-Jaw Chuck

Actually if I am following correctly, I believe they do make such a thing. One of the people on my clock forum in the UK has a nice small lathe set up with 3-jaw chuck and what he calls and adjustable backplate. He says with that setup he doesn't need collets. He chucks up the work and adjusts the back plate to get on center.

David
 
Last edited by a moderator:
There is nothing that would prevent us from making an oversized back plate that recessed the entire width of the chuck within a shallow counterbore, with radial adjustment screws pointing inward.

Sure that would allow centering the 3-jaw chuck very accurately.
But, isn't that essentially the same as putting your 3-jaw chuck into a four jaw chuck?
-brino
 
Last edited:
Speaking of Shars, I do not own a Shars lathe chuck but have a lot of tooling from them and am impressed.
 
Hi all
Would be ok to ask what the darkzero "tap- tru" method is? I tried search every where and could not find a thread on it. I' getting ready to mount my plane back Bison chuck and would like do the best job possiable. For the best results.
Any info would be greatly appreciated.
CH
 
Sure that would allow centering the 3-jaw chuck very accurately.
But, isn't that essentially the same as putting your 3-jaw chuck into a four jaw chuck?
-brino

Yes. Its certainly not a new idea. The first one I saw was on a Tubalcain shop tip youtube. He had an old 3 jaw chuck with the "4 jaw" adjustment feature built in. His comentary indicated it was a highly desireable unit.
Sorry, don't remember the brand he said.
I was jealous of course.......
 
Hi all
Would be ok to ask what the darkzero "tap- tru" method is? I tried search every where and could not find a thread on it. I' getting ready to mount my plane back Bison chuck and would like do the best job possiable. For the best results.
Any info would be greatly appreciated.
CH

I certainly didn't come up with the method, that's just what I call it.

For plain back chucks, normally the register on the adapter & chuck have a close tight fit. Whatever the chuck's runout is you are stuck with unless you grind the jaws. For the "tap-tru" method, you turn down the register slightly so you get a loose fit. Now you can adjust the runout of the chuck by leaving the mounting bolts loose, tap with a hammer or whatever to get minimal runout, then tighten the bolts.

If you have a brand new Bison chuck w/ Bison adapter, I wouldn't do it to it but that's just me. I've only done it to inexpensive chucks.
 
I certainly didn't come up with the method, that's just what I call it.

For plain back chucks, normally the register on the adapter & chuck have a close tight fit. Whatever the chuck's runout is you are stuck with unless you grind the jaws. For the "tap-tru" method, you turn down the register slightly so you get a loose fit. Now you can adjust the runout of the chuck by leaving the mounting bolts loose, tap with a hammer or whatever to get minimal runout, then tighten the bolts.

If you have a brand new Bison chuck w/ Bison adapter, I wouldn't do it to it but that's just me. I've only done it to inexpensive chucks.

Ok I understand. It is not a new bison in fact is an older one but new to me, and is a plain back no adjustment at all. It has never been mounted and I just bought a cast iron back plate that needs machining. If it come out good then I won't need to do this. If it does not then I will try to improve it this way.
Thanks for the clarification on the method.
CH
 
Last edited:
Back
Top