On 2011-03-09, wrote:
I was going to make a quick and dirty dividing head to use with my
Taig chucks on my X2 mill.

I thought I would basically run a shaft through a block of aluminum
with 3/4-16 thread on one end and a dividing plate on the other. Then
I thought: What shaft? What bearings?

Primary concerns here are not the rotation loads but absence of radial
and axial movement of the shaft.

I am not sure what engineering principles apply. Would an aluminum
shaft with a slip fit through a hole in the aluminum block suffice?

Likely to suffer galling.

Presumably a steel shaft would wear out the aluminum.

Actually -- a polished steel shaft would be a better bearing
with the aluminum housing than an al-al interface. keep it lubed, of
course.

Would it be
better to use a steel shaft with bronze bushings? Ball-bearings seem a
bit of an overkill.

How much load forces are you expecting?

Maybe by the time I think this through I will find it expedient to get
a Taig headstock for $60+ and use it as a base for the project (a
common approach, apparently). However, I would still like to know what
is the correct approach if building from scratch.

Or -- perhaps get an old Unimat or Emco-Maier dividing head, if
you need no more than 60 divisions.

Of course -- the Unimat ones go for crazy money these days, if
you can find them on eBay at all. People are *collecting* these things
instead of using them. :-)

Enjoy,
DoN.

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