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Preferred Back Plate Material

MyLilMule

Hot Rolled
Joined
Jan 5, 2021
Location
Ohio, USA
I picked up a 10" chuck for my 13" SBL with a 1-7/8"-8 spindle thread.

What is the preferred/proper material from which to make a back plate? I saw somewhere that cast iron is the only thing I would want to use.

I was given a chunk of 4150 from which to machine the back plate, but that's considerably harder than cast, of course.

Is there a reason NOT to use the 4150?
 
Yes, It rings like a bell. Cast iron is a dead material. Hit it with a hammer and you hear a clunk whereas striking steel the same way and it rings like a bell promoting tool chatter.
 
I've used both steel and CI and couldn't tell any difference in use. I always thought CI was a little better to use as it's less likely to gall and get stuck on a threaded spindle.
 
There is no need to have a close fit on the threads, so long as the face contacting the spindle is square to the axis. That pretty much eliminates the chance of galling. But, a coat of oil can't hurt.
 








 
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