Bison semi-machined chuck backplates

Recently got a Bison semi-machined 1.5-8 chuck blackplate from MSC. I've found that the threaded bore and spindle register it comes with is _larger_ than that of my lathe. Am I missing something or is this a defect? I was under the impression that semi-machined BPs were supposed to be slightly undersized so they could be finished to match the machine. This one's so loose it wobbles around quite a bit--larger than 1.5" by a bit.


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That's why I only get totally unfinished backplates, and do all the boring and threading myself.


Reply to
Jon Elson

Thread wires are cheap. Buy a set, learn how to use them, and then measure your spindle thread. It might be undersize. On my SB9, it measures 1.503" which has caused me a bunch of grief.

MSC *will* take it back. If your spindle thread is correct and the backplate is loose then call their customer service.


GTO69RA4 wrote:

Reply to
Grant Erwin

Before I learned to thread I bought large nuts and welded them in a steel

3/4 inch plate and then proceeded to make my own plate. They are still in use now. After welding they actually tightened up a bit and required a little force to install. After several on and offs they now fit like a glove. Note, they did take a "set" about a month later and required a little fine tuning to make it perfect.
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