Need new / quality backplate for 3 jaw D1-5

I got some marking blue just the other day. I should tear this down and check that. Good points.
 
This maybe escalated beyond current comfort level - Skimmed the surface that registers the spindle. Runout was nil. However, this affects two things.

1. Center registration
2. Stud "stickout" - If I continue I'm going to need to take enough off the surface to get a full turn out of the studs.

I'm sure I can figure out the angles for the registration surface and correct them, but I need the lathe for other actual business so it's gonna get tabled for a while. :)

Also, I hate cast iron.
 


Part: 7-878-085F

Measurement K on the backplate seems to align with measurement D on the SK8 chuck.

Anyone care to double check my work?
 
Had a need to use the 3 jaw that came with my 1440GT - 8 inch "precision" variety.

The chuck itself seems nice.

But the cast back plate- wow. I took the chuck off and put an indicator on the face of the back plate - ~15 thou run out. I skimmed it and got it running true. I marked the position of the plate, took it off, put it back on, weeble wobbles again. The headstock side of the plate is obviously not flat and I don't have a great way to deal with that.

I have other high quality chucks that I use daily with no problem, so I don't think it's user error.

Where can I source a quality precision ground backplate for this chuck?
The studs on my D1-5 mount are threaded and held in with a setscrew. Pull the studs out and face the headstock side of the backing plate.
 
The studs on my D1-5 mount are threaded and held in with a setscrew. Pull the studs out and face the headstock side of the backing plate.

I did that. I need to do it "more" so the studs can go in one full turn, then I'd need to open up the center registration. I just don't want to mess with it. I'd rather turn it into a door stop.
 
A machinist will fix what he can... Come on Aaron, this is not trash, it just needs some accuracy. And it's good practice at fitting .. And you'll feel good about it in the end.
 
I did that. I need to do it "more" so the studs can go in one full turn, then I'd need to open up the center registration. I just don't want to mess with it. I'd rather turn it into a door stop.
Grizzly has D1-5 backing plates in 6-8-10 inches.
 
I got the Bison finished backplate today. It is beautiful and assembled. Perfect fit. The only problem is the bolts are inch and not metric like what came with the chuck. No big deal, mcmaster has a package shipped to me almost every day anyway :cool:
 
Got it all bolted up

3 thou runout at the jaws and 4-5 8 inches out from the jaws. That was just a quick check. Seems acceptable for the type of work I'd put in a 3 jaw.
 
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