3 jaw scroll that I don't know how to adjust vs independent 4 jaw backing plate

Unless you're going to run setru type chucks I would try to get direct mount chucks. Significantly shortens the chuck thus increases rigidity. Probably not a big deal now w/your larger lathe.
 
Are these kinds of backplates hard to make? My threaded backplate came out well and I'm really a beginning hobby machinist. Toughest part were the spindle threads, and your backplate won't need that. Or do you have more money than time? I can understand that.
 
Difficult to get right. It can be done.
 
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ddickey said:
Difficult to get right. It can be done.
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What is the hard part vs doing a threaded backplate? A lack of reference? I have no idea, which is why I am asking.
 
D1 plates/chucks are dual contact. To have a proper fit they must just come into contact with the back (flat) part of the plate to the flat of the headstock. Any more or less and accuracy is lost. The taper is 7.125 degree i think.
 
ddickey said:
D1 plates/chucks are dual contact. To have a proper fit they must just come into contact with the back (flat) part of the plate to the flat of the headstock. Any more or less and accuracy is lost. The taper is 7.125 degree i think.
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Thanks for the explanation. Yeah tapers are hard, especially coming exactly to a flat. Doesn't take much of a taper error to mess things up. It's amazing to see the effects of miniscule taper error translate into major axial changes in length.
 
Yes. Mr. Crispin has an excellent video on regrinding his D1 spindle nose.
 
Aukai said:
That was a lot of research, thank you.
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As frugal as I am I have made plain scroll chucks into set true chucks. If there is enough register width I have turned register dia a little smaller and drilled and tapped 4 places around chuck od to adjust chuck true.
And there is no law saying I could not take a 6 inch backplate and counterbore it to hold a 5 inch chuck and adjust it by tapping 4 holes into it.
Even if I had to Adjust the chuck for a different dia part it is like adjusting a 4 jaw chuck. And done in minutes.
 
Aukai said:
Thank you John, Dave I need 2 6" D1-6 backing plates also. I need/want to change over 4 total.
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Someone on the unfriendly forum is selling 2 Toolmex 8” D1-6’s for $250 each if your looking.
 
Thank you I have the 8" chucks covered I have 1 10" 4 jaw, an 8" 3 jaw with the machine, then the 2 plates I have now will be for my Pratt 8" 3,and 4 jaw chucks that are on D1-4s now. If I get a 5", or 6" backing plate I will keep 1 of my 4 6" chucks, and sell the other 3, I'm not sure which one to keep. I'll get some guidance on that later, Samchully, Rohm, Buck, and Pratt are my choices.
 
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