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I have a new vertex dividing head with 1.5x8 tpi threaded nose & trying figure out how to proceded on mounting a 4" chuck I just acquired. The chuck has integrated threaded backplate to save me machining a sepearte backplate casting & then mounting a plain back chuck.
The problem: the chuck only threads on a couple rotations & then seems to bottom out prematurely. Its flat ID segment hole (before the internal threads) kind of tightly fits (or bottoms) on the matching flat segment on the DH. I would think it should screw on all the way until its back is flush with the lip on the DH spindle. If I screw the casting plate (included with DH) on, it does this. Same for the protection ring.
So I measured:
1.515" = OD of DH spindle flat segment
1.512"= ID of 4" chuck flat segment
1.515 = ID of casting plate (accessory included with DH)
1.590" = protection ring.
So looks like the chuck is 0.003" (1.515-1.512) smaller ID & thats the hold-up. The way I suspect this is supposed to work for accuracy is thread the accessory all the way until its back face is flush against the DH lip so it snot just depending on threading to be axial with teh DH spindle?. Maybe the chuck is meant for a 1.5x8 tpi lathe nose? (its a deeper relief too).
I can probably set up the 4" chuck in my lathe & relieve the ID bore a smidge. Thought I would check first though, its hard to put metal back on.
The problem: the chuck only threads on a couple rotations & then seems to bottom out prematurely. Its flat ID segment hole (before the internal threads) kind of tightly fits (or bottoms) on the matching flat segment on the DH. I would think it should screw on all the way until its back is flush with the lip on the DH spindle. If I screw the casting plate (included with DH) on, it does this. Same for the protection ring.
So I measured:
1.515" = OD of DH spindle flat segment
1.512"= ID of 4" chuck flat segment
1.515 = ID of casting plate (accessory included with DH)
1.590" = protection ring.
So looks like the chuck is 0.003" (1.515-1.512) smaller ID & thats the hold-up. The way I suspect this is supposed to work for accuracy is thread the accessory all the way until its back face is flush against the DH lip so it snot just depending on threading to be axial with teh DH spindle?. Maybe the chuck is meant for a 1.5x8 tpi lathe nose? (its a deeper relief too).
I can probably set up the 4" chuck in my lathe & relieve the ID bore a smidge. Thought I would check first though, its hard to put metal back on.
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