Material and thickness suitable for a 5" chuckplate

[mac1911]

So much work I figured I may as well just start from scratch.

Is thete a reason cast iron has to be used? For a thteaded spindle I guess I could understand.

I dont have a answer. I made my first plate from aluminum cause its what I had.
I just started working on a cast plate with a salvaged treadmill motor flywheel

 

[WobblyHand]

Cast iron seems to be the favored material. I think because it has damping properties, and is heavy. It also machines very nicely.

I made my own cast iron back plate, threaded to 1.75"x8. I had never done anything like this before, as I was just starting out machining (not all that long ago). If I could do it, so can you. Was surprised it was nowhere as difficult as I originally thought. The hardest part was deciding to do it, overcoming my fears, uncertainty and doubt, after that, things were much easier. My back plate "journey" is documented at https://www.hobby-machinist.com/threads/making-a-backplate-for-an-er40-set-tru-chuck.98124/. I'm quite pleased how it came out, I use it a lot.

 

[Smithdoor]

Check with LMS to confirm this will fit (they say SIEG C4/SC4 8.5 x 16):

View attachment 473571

You still get to machine the boss to fit the back of your chuck.

I agree

I just purchased one in December works great for 4 jaw chuck on my new lathe.

Do not forget order the studs with chuck.

Dave