On Thu, 16 Nov 2017 15:59:07 -0700, "Bob La Londe"
wrote:

"Ed Huntress" wrote in message
.. .

On Thu, 16 Nov 2017 11:50:03 -0700, "Bob La Londe"
wrote:

I've decided I need to make some electrical tool height setters for my
machines with a fairly small foot print. I've figure out my design so they
will have a lot of over travel and good repeatability, but I am wondering
about the anvil or touch surface. The analog indicator type I am using now
seem to have a steel surface, but they are softer than the tools and they
will ding fairly easily if you make a mistake. Because I do a lot of flood
machining I was thinking stainless might be the ticket. 304 for the body,
and 303 or 416L for the anvil with an acetal insulator. A harder
machineable insulator might be better, but I am not sure what.

Definitely NOT something like HDPE since its compressible, and spring
pressure over time might cause it to extrude and lose positional accuracy.
I don't really have room for an off material setter to to be used all the
time. Adding soft buttons and macros to semi automate the tool height set
is pretty easy for my controls. It would improve my machine times, and
reduce my necessity to deburr between tool changes more easily creating
consistent parts.

See if you can get a small piece of Macor, a machineable glass
ceramic. I've machined it on my South Bend lathe, so there's nothing
tricky about it.

If you turn it, just cover the bedways with some aluminum foil or
oiled paper.

******************

You are the third person to suggest machinable ceramic, and the second to
suggest Macor specifically. McMaster stocks it. I am leaning more and more
towards trying it. I'm just concerned about how it will react to the spring
loaded anvil returning to position when a mill retracts. I guess one way is
to try it and find out.

Yeah, I think you'd just have to try it. It's not really tough, but
it's not particularly brittle, either. I have a demo piece that the
Corning people machined for me at an IMTS, probably 1980. I've whacked
it and given it some rough treatment over the years. It's still
intact.

It was the first of those machineable ceramics, but I think there are
others out there now. Check them out.

--
Ed Huntress