On Fri, 19 Jul 2013 05:33:17 -0500, Karl Townsend
wrote:

...
How is the CNC drawbar engaged? (curious) I thought drawbars were
just glorified, dual-threaded long bolts which engaged the bit from
the top, drawing it into the tapered spindle hole.

power drawbars have splined ends with points on the end of the
splines. There's a female mating spline on an electric impact wrench
and an air cylinder to drop it in place.

OK, that covers the top end, but what about the bottom? Are the bit
adapters tapered and do they have threaded tops like their manual
counterparts? I don't yet grok the mating method, -especially- after
seeing the spindle parts you showed. I only saw female bottoms, if you
will. (quiet, Mikey.


Deep 7/8" impact socket and pneumatic impact wrench, Karl. Use a
large diameter hose and high pressure air for maximum torque. Try it
both ways to rule out left-hand threads. Maybe wedge an old bit in
the collet to slow down the turning if it slips on you.

Wish I'd ask you BEFORE I broke it

I'm glad to share my vast (2+ hours) experience on milling machines
with you.

--
Always bear in mind that your own resolution to
succeed is more important than any one thing.
-- Abraham Lincoln