Need new / quality backplate for 3 jaw D1-5

LVLAaron

LVLAaron

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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?
 
I would probably put my 4 jaw chuck on with a 2" bar protruding 3-4". Dial it in perfectly. Put 3 jaw chuck (with backplate attached but pins removed) on backwards clamped to bar. Check it but then make a skim cut, if I believed it not to be perfect. Should at least get a true registration surface. Once that's true to the machine, I would have then made a truing pass on other side. Hard to believe one slipped thru with that much runout. On my PM-1340GT with precision 3 jaw, I get around .0015" in 1 position that's repeatable and plenty good with a 3 jaw. After that first cut, it's true anyway and unless you need to put back in chuck for 2nd op, that's all that matters.
 
Aye, that's a good idea. I've got nothing to lose other than the frustration of cleaning up cast iron :)
 
Put some rags, paper towels, foil over the ways, use a shop vac. Not a big deal, it's a tool.
 
Been using a small hospital blanket and shop vac - foil is a great idea.
 
LVLAaron said:
www.smalltools.com

Bison Finished D1-5 Adapter Plate 7-878-085F for 8" Chucks

Bison Finished D1-5 Adapter Plate 7-878-085 for 8" Chucks
www.smalltools.com www.smalltools.com


It seems like this would fit. Are the "3 bolt holes" on chucks generally the same?
Click to expand...

That plate looks like it has 6 mounting holes, which would be at 60 degree intervals, if you have 3, then you'd need 120 degrees, so every other one, should be right.................as long as the diameter is the same. You have a mill.
 
Did you not just recently get this new from PM? Have you contacted them about the issue?
 
LVLAaron said:
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?
Click to expand...
well if you took off the chuck and refaced it, it should be true. What you should do is mark the plate and spindle (with paint) where it should match... then always mount it there. That should do it.
 
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