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Chuck Back Plate

bss1

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#1
I have two 5" Bison plain back chucks left over from a South Bend 9" lathe I used to own. One chuck is a four jaw and the other a 3 jaw scroll chuck. After hoisting the larger chucks on my newer PM1340GT, I am considering putting D1-4 back plates on them to use on smaller projects. Over the holiday, I was looking at pricing for the back plates which range from around $60 for Grizzly to over $200 for Bison.

My question is how important is the quality of the back plate to the accuracy of the chuck? If I can buy the cheaper back plates and I may try to put these back in service if they will be fairly accurate. I am sure the issue with quality is the same as everything else, but can I get the cheaper back plates and do some fitting and end up with an accurate set up? If It will take a $400+ investment to get there, then I would probably just save the money and continue to hoist the heavier chucks around for now.

Thanks for your help.

Brad
 
Last edited:

anoyes

Swarf
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#2
Do the less expensive backplates have a bit of stock to remove? If so, and you could machine them in place, I'd think they'd be very accurate. Good luck!
 

Bob Korves

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#4
For various kinds of chucks it is probably worth buying quality back plates. For something like a faceplate or dog driver all that really matters is whether it will fit the spindle and what you want to mount to it, and the cheap imports do just about as well at that. Any back plate will need some work done to it.
 

bss1

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#5
Thanks for the help guys. After all of the expense getting the new machine tooled up I have decided to try the economy route for now and ordered the plate mentioned by Jbolt from CDCO. I needed a few more tool holders anyway to add to the order.


Sent from my iPad using Tapatalk
 

Bob Korves

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#6
D1 series back plates and also integral chuck mounts need to be checked for proper fit to the spindle nose before doing any machining on them or fitting anything to them. The back plate must fit the spindle taper snugly and at the same time seat COMPLETELY tight to to the spindle face. A light bump with a dead blow hammer should remove the installed back plate from the spindle. If not, you have some work to do. I spent most of a day learning, understanding, and then properly fitting the D1-4 face plate and the two chucks that came with my Kent KLS-1340A lathe after wondering why there was random runout and wobble in them.
 

jbolt

Active User
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#7
D1 series back plates and also integral chuck mounts need to be checked for proper fit to the spindle nose before doing any machining on them or fitting anything to them. The back plate must fit the spindle taper snugly and at the same time seat COMPLETELY tight to to the spindle face. A light bump with a dead blow hammer should remove the installed back plate from the spindle. If not, you have some work to do. I spent most of a day learning, understanding, and then properly fitting the D1-4 face plate and the two chucks that came with my Kent KLS-1340A lathe after wondering why there was random runout and wobble in them.
That's interesting to hear Bob. I went through the same thing you describe on my old lathe with a D1-4 spindle.

On my new lathe with a D1-5 spindle I have four checks. Two 8" Gators, a 6" Import fitted to a South Bend back plate and a Bison set-tru 5C . All fit out of the box and will repeat on-off-on within a tenth or two with no tapping required to remove.
 

petertha

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#8
I bought a D1-4 backplate for my 5" 3J Gator chuck & it seems very well made. It fits the nose spindle perfect & has no runout on the face I can detect. They leave a smidge of material on the boss for you to turn so the chuck is concentric (to the degree the backplate recess is true).

ps - I had an issue fitting the taper nose portion on a face plate. You can read about the fix halfway down this post
http://www.hobby-machinist.com/threads/d1-4-slotted-faceplate.52482/#post-438366