On Mon, 7 May 2018 06:51:25 -0700 (PDT), "
wrote:

One more thing - an unbalanced motor spinning at 24,000 + rpm will destroy itself in short order. I suspect that the motor itself will be the least of your worries.

At the same time, is this engraving device for a pantograph, or similar, such that an off-the-shelf engraver would not be suitable? There are some pretty good ones out there.

https://www.gesswein.com/p-2557-fore...Cs5 QQAvD_BwE

That for the price will probably be competitive with your home-brew at the end of the process.

Peter Wieck
Melrose Park, PA
This engraving spindle is for use in a CNC mill. Ideally it will
sit in the tool carousel along with the other 20 tools and be
connected to power and cooling automatically. But I will probably need
to manually plug in power and cooling connectors.
I use different rotary tools for engraving and micromilling. The
smallest engraving tools I use are .015" diameter at the tip. The
smallest milling cutters I use are similar in size. The graver you
linked to is a hammer type and is not the type of engraving I do.
There are several ways to engrave and what my customers want requires
rotary tools. I am really just doing shallow machining when I engrave,
not any kind of artistic stuff. Letters, lines, numbers, that kind of
thing.
The top spindle speed of my main spindle is only 7,500 RPM. I do
have a sub spindle that spins at 24,000 RPM but it is too big to fit
in a CAT 40 tool and so is instead mounted in a clamp which in turn
clamps around the main spindle housing. A kluge.
I have some hobby BLDC motors but the ones with enough power for
high feed rate cutting max out at 24,000 RPM and I really want 40,000
RPM. I have experimented with the motors spinning a tool at 24,000 RPM
and surprisingly the things were pretty well balanced. But as I said
they can't be fed along very fast.
Eric