Help choosing a 4 jaw chuck for my SBL 9A

[Vince_O]

Ok guys Im wanting a 4 jaw chuck for my lathe, SBL 9A. I have a 6 inch cushman 3 jaw self centering on it now, but I cant hold irregular pieces, as you more experianced people know.

I read the thread with the write up from DZ on his "clean up" on his latest Asian chuck. I was looking at some on epay, and one from Shars says plain back. I dont know what I have, as far as plain back ect, or what options they come in.

Could someone please explain this term to me, and maybe some decent options. Im not making parts to go to the moon, but want to do best I can within my, very, limeted skill.

 

[12bolts]

Vince,
You want approx a 5" dia 4 jaw for your 9" SB. Plain back means you will need to fit it to a faceplate/chuck backing plate in order to screw it on to your spindle 1 1/2 x 8TPI.
These are not too difficult to make, (do a search on here, there are a couple of threads), it will be a good learning experience for you.

Cheers Phil

 

[Vince_O]

Phil

So can I just use the back plate I have now then?

Also Im guessing you guys recomend an independent style, how else would you hold unusual shapes or bore off center.

 

[JimDawson]

Phil

So can I just use the back plate I have now then?

Also Im guessing you guys recomend an independent style, how else would you hold unusual shapes or bore off center.

You don't want to take the back plate off of your existing chuck. Buy or build one for your new chuck. Once you get the chuck and back plate, you will have to machine the back plate to fit he new chuck. Screw the new back plate onto your spindle, face it off so it is true to the spindle, and then machine the OD to size so it fits pretty snug in the recess in the new chuck. Drill & tap the mounting bolt holes and enjoy your new chuck.

Yes, get an independent style.

 

[Don B]

Phil

So can I just use the back plate I have now then?

Also Im guessing you guys recomend an independent style, how else would you hold unusual shapes or bore off center.

You'll want a back plate that's dedicated to your 4 jaw, you could make this yourself or purchase one, you can also hold iregular shapes with a "lathe face plate" and clamps or bolts.

 

[12bolts]

Yeah Vince,
as the others pointed out. Make, or buy a new backplate for your new chuck. Bear in mind that even a bought one will need to be machined to fit your lathe/chuck/spindle. The chances of the backplate you have on your 3 jaw now being useable with a different chuck are infitissemal.
Basically you single point a thread into the backplate that fits your spindle. Screw this onto your spindle and machine a shoulder, (register) that will fit the back of your new chuck. Then bolt the new chuck on and away you go. Its a bit more involved than that but thats the basics of it.
A purchased backplate may have just a hole ready for threading, or you can get them ready threaded, but you will still need to turn the register to suit your chuck.

Cheers Phil

 

[AR1911]

I would suggest a 6-inch 4-jaw, as that is what was supplied with the SB9 and other 9" lathes. In general, the 4-jaw is one step up in diameter from the 3-jaw.

 

[Vince_O]

Heres what Im looking at on Epay



350477709766

 

[Vince_O]

Ok I took a look around and found this chuck. Fits my lathe perfect. Looks like it hasnt been used, other than one screw on the face is a little boggered up. I can see this is going to be a HUGE learning curve for me. The nice thing is the jaws are reversable.

Thanks everyone for your input on this post