Received an 8" 3 jaw chuck with my new dividing head and just thinkin.....

[verbotenwhisky]

I bought a new dividing head and with it came an 8" 3 jaw chuck which is NICE. The chuck is connected to the back plate with 3ea M10 Allen head cap screws. I have a 6" 3 jaw chuck on my lathe and I would like to set this new chuck up to be used with the lathe but I am looking at the 3 screws...... Thoughts anyone?

 

[MyLilMule]

You might need to make or purchase a back plate. Without any additional specifics on your lathe, that would be a guess.

 

[verbotenwhisky]

You might need to make or purchase a back plate. Without any additional specifics on your lathe, that would be a guess.

I was thinking about making a back plate, I have a PM1236 with a D1-4 connection, I am just wondering what others thoughts are on it being connected with 3 screws?

 

[MyLilMule]

Ah, OK, I misunderstood. As long as the screws are of good quality, and the threaded holes the attach too are correctly machined, I wouldn't worry about them. I'm not an engineer, I would imagine there is a way to calculate the failure point, but I suspect your lathe won't be able to get there.

I suppose there could be a rigidity issue at higher RPMs maybe? Only one way to find out.

 

[FOMOGO]

What size are the 3 threaded bolts? Depending on the chuck you could drill and tap new holes for a D1-4 backing plate. Mike

 

[verbotenwhisky]

What size the 3 threaded bolts? Depending on the chuck you could drill and tap new holes for a D1-4 backing plate. Mike

I need to check for certain but I believe they are M10x1.25, certainly not any bigger...

 

[verbotenwhisky]

If these were good ol' 3/8"x 16UNC I would put grade 8 bolt in it and I would be okay with it...

 

[markba633csi]

Usually, the bolts alone aren't responsible for holding the chuck in place. The backplate and chuck normally have a step recess so they
are mated tightly together
The bolt circle and recess will both likely be different for 6" vs. 8" chucks

 

[verbotenwhisky]

Usually, the bolts alone aren't responsible for holding the chuck in place. The backplate and chuck normally have a step recess so they
are mated tightly together
The bolt circle and recess will both likely be different for 6" vs. 8" chucks

You are correct, and my brain just clicked, the only load will really be holding the chuck so that it doesn't rotate around that "step" and/or fall off of it.... I think my brain needs a restart now.... Some times I get so focused on something that I do not see the forest for the trees....

 

[derf]

I'd leave it on the dividing head, that probably what is was purposed for. Lathe chucks are made to spin at hi speeds and are usually balanced for such things.