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request for chuck recommendations

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greenail

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#1
My 8x16 lathe has a 125mm backplate that is integrated into the spindle. It has 3 mounting holes for a 125mm chuck. I have 3 and 4 jaw self centering chucks and I want to acquire a 4 jaw independent chuck.

Quesitons:

6" (160mm) seems more common. Should I go with this or the 5" (125mm)

should I buy a backplate or make one? If I make one what is the best material to make it out of and what thickness would work?

Is there a readily available 4 jaw independent chuck with 3 holes and a 95mm registration boss? I have not been able to find one.
 

pontiac428

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#2
Hello neighbor,

It's usually easier to buy or make a plate for the chuck you want or have than it is to find a chuck for a plate you have. I'd recommend buying a chuck mounting plate blank and fitting it to your chuck (whatever you end up with). As for size, you'll have to check for yourself, but on a 8" lathe I would probably want the 5" chuck. You can fit a 6" on there, but you might not have the clearance once you open it up and the jaws protrude from the chuck body. Depends on your particular machine, but if clearance is an issue with a larger chuck, you are probably going to gain capacity by going with a smaller chuck that you can max out. Bonus is that 5" chucks cost less. Bison, Burnerd, and Buck all make 5" offerings.

Pics would help. Folks on this board are happy to help; if you show your setup with a few pics, the comments will pour in.
 

hman

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#3
+1 on recommending the 5" chuck. Not just for clearance issues, but also because it's significantly easier to spin - less load on the motor, etc.
 

greenail

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#4
Hello neighbor,

It's usually easier to buy or make a plate for the chuck you want or have than it is to find a chuck for a plate you have. I'd recommend buying a chuck mounting plate blank and fitting it to your chuck (whatever you end up with). As for size, you'll have to check for yourself, but on a 8" lathe I would probably want the 5" chuck. You can fit a 6" on there, but you might not have the clearance once you open it up and the jaws protrude from the chuck body. Depends on your particular machine, but if clearance is an issue with a larger chuck, you are probably going to gain capacity by going with a smaller chuck that you can max out. Bonus is that 5" chucks cost less. Bison, Burnerd, and Buck all make 5" offerings.

Pics would help. Folks on this board are happy to help; if you show your setup with a few pics, the comments will pour in.
It looks like the bolt hole pattern is 108mm which is common on self centering chucks. Oddly it seems the self centering chucks have 3 screws and the independent 4 jaw chucks all have 4 screws. I would guess this is because you are more likely to have something out of balance in a 4 jaw chuck. Is there some other reason?
 

pontiac428

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#5
3 (or 6) vs 4 bolts is due to the layout of the jaws. Independent chucks usually have the bolts inboard, because there is no scroll to interfere with placement. Scroll chucks always have the main mounting bolts on the outer edge. There are definitely exceptions out there, but that's the primary reason. If you're worried about fitting it up, don't- fitting a mounting plate, registering the chuck, and drilling/tapping the mounting bolt holes is very easy to do with only your lathe and a drill press.
 

markba633csi

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#6
Check with Little Machine Shop, they may have a 5" that will bolt right on
M
 

Kenny G

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#7
Yes LMS (Little Machine Shop) will have what you need they usually have both fully machined and those that need minor machining on the chuck registration side. I am in the same mode buying an adapter. I am assuming that your 8 x X has a flange type spindle.
 

greenail

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#8
Yes LMS (Little Machine Shop) will have what you need they usually have both fully machined and those that need minor machining on the chuck registration side. I am in the same mode buying an adapter. I am assuming that your 8 x X has a flange type spindle.
yes the backplate (flange?) is integrated into the spindle. It is a 38mm bore though.
 
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