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Noob- Bison Chuck and Mounting Plate

ShelbyG

Plastic
Joined
Feb 9, 2019
I'm a complete noob, so please excuse my ignorance.

I purchased a Bison 4 Jaw combination chuck, plain back model 7-848-0800. I have a PM12x36GT lathe with a D1-4 spindle. I also purchased the 7-875-084 back plate.

However, now that they are here, I'm not sure how the back plate is supposed to mount to the chuck. The chuck has 6 mounting bolts and is tapped to receive the mounting bolts, but the back plate only has the three studs with no holes drilled to mount the plate to the chuck.

In looking at the markings on the back plate, it does appear to be the 7-875-084 and all of the images I can find online and in Bisons catalog show 3 mounting holes already drilled.

Am I supposed to finish the back plate by drilling the mounting holes or did I get the wrong part? I may be way too early in my machining education to try and accurately locate the points to drill mounting holes at this point in my learning experience.
 
Can you send them back? You could have bought a direct mount chuck.

Yes, what you have is up to you to mount.

EDIT- did you mean to buy a combination chuck???
 
Am I supposed to finish the back plate by drilling the mounting holes or did I get the wrong part? I may be way too early in my machining education to try and accurately locate the points to drill mounting holes at this point in my learning experience.

I think that I'd start with a plain backplate and mark out the bolt circle, drill and counterbore for appropriate socket head cap screws. You can probably fit it on the semi-finished plate as it it but you'll probably have to machine off the set-tru stub and machine a new register. Might want to look at this backplate before you go to that effort: 3-878-084P - BackPlate 8" D1-4 Fully Finished,Scroll - Toolmex Industrial Solutions as it appears to have the right number of bolt holes, maybe on the right diameter.

on edit: that's an odd chuck to buy if it's your first chuck. 4 jaw scrolling independent jaw is neither fish nor fowl and is really handy in only a few specific instances.
 
Can you send them back? You could have bought a direct mount chuck.

Yes, what you have is up to you to mount.

EDIT- did you mean to buy a combination chuck???

Yes I did mean to buy the combination chuck, perhaps because of my ignorance, I thought I was getting something that would be more versatile. I did not find a D1-4 direct combination chuck when I was looking, but it doesn't mean I overlooked it.
 
I think that I'd start with a plain backplate and mark out the bolt circle, drill and counterbore for appropriate socket head cap screws. You can probably fit it on the semi-finished plate as it it but you'll probably have to machine off the set-tru stub and machine a new register. Might want to look at this backplate before you go to that effort: 3-878-084P - BackPlate 8" D1-4 Fully Finished,Scroll - Toolmex Industrial Solutions as it appears to have the right number of bolt holes, maybe on the right diameter.

on edit: that's an odd chuck to buy if it's your first chuck. 4 jaw scrolling independent jaw is neither fish nor fowl and is really handy in only a few specific instances.

I was concerned once it arrived that I had bit off more than I should of. Thanks for the suggestion, I think I'll look into that.
 
Unless you have that very specific use I would send it back and get a nice direct mount 4 jaw...with the money you save could probably get a nice 3 jaw too.
 








 
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