Where to find spindle adaptor ?

[Roy Norris]

I need to buy a spindle adapter that will reduce the 2 1/4" 8 tpi spindle of my dividing head to 1 1/2" 8 tpi so that I can mount a face plate with 1 1/2" 8 tpi threads. I'll need excellent concentricity (0.0005 or better) . Any suggestions as to where this could be acquired or made?

Best regards -- Roy Norris

[ViperTX]

I seriously doubt that there is such an animal....I guess a plummer would beg to differ with me...since they use such items...coupler & nipple....I suspect that you're not planning to spin this at any great speed?

What don't you just bore out the face plate and thread it....no meat on the hub....

[DareBee]

Exactly^

1) Get a face plate that fits.
2) rework your existing faceplate.
3) Rework the dividing head spindle.
4) Get a new dividing head.

You could make an adapter but adding 3" or so to the overhang (rigidity) plus the inaccuracy of 2 accumulated tolerances would be unacceptable in my books.
The remachining in a high accuracy shop (CNC OD grinder)would be expensive - especially for the spindle - but it can be reground easily to a .0002 tolerance if that is how you want to go (Assuming there is a small enough spindle bore to have stock).
Dividing heads are pricey as well.

No easy fix - sorry bud

[Roy Norris]

Thanks for the suggestions.

What I had hoped to do was to turn 8" diameter 1/4" thick brass gear blanks on the face plate of my South Bend 10-K (1 1/2" x 8 tpi) and then remount the entire face plate & gear blank on my dividing head on the mill without having to remount and recenter the gear blank on a second face plate sized for the dividing head (21/4" x 8 tpi). Sounds like that isn't going to be possible. The only affordable universal dividing head I could find (and have ordered) has a 2 1/4 x 8 tpi threaded spindle (Vertex BS2 out of Taiwan).

I guess I will just have to spend some time with a dial indicator recentering and remounting the gear blank on a second surface plate sized for the dividing head, unless any of you can figure a better way to do this.

Best regards -- Roy

[ViperTX]

Does the gear blank have a bore or mounting holes that you can use to center it?

[Roy Norris]

Yes, it will have a small hole, perhaps 1/8 to 1/4 (these are clock gears) that will be drilled on the lathe at the same time as the blank is turned to the proper diameter. Perhaps it could be used in some way to speed up centering on the face plate of the dividing head. It is too small, of course to mount the blank on a mandrel for subsequent cutting of the gear (the disc of the gear blank has to be supported with a wooden plate mounted to the face plate, which in turn, the brass gear blank can be mounted to.

Perhaps I could use a small mandrel held in a collet on the dividing head spindle just as a centering device ?? Then attach the gear blank firmly to the face plate wooden spacer/support. What do you think ?

Best regards -- Roy

[eqreservoir]

Just a thought not being familiar with your lathe or dividing head. If the dividing head and lathe has a MT in the spindle. Machine a morse taper shank to fit the smaller of the tapers lathe vs dividing head. the morse taper then threaded to fit the faceplate. Maybe then you can move them back and forth with sufficient accuracy.

HTj