On 8 Mar 2004 04:39:38 -0800, (Paul Probus)
wrote:

I
also am unsure of what component ratings will change because the
router I have says that it is rated for 3 hp, and can pull a max of 19
amps. This is why I am leary of the ready made speed controls, as
they are limited to 15 amps.

I was in error when I said my "15 amp" speed control was from
Rockler. It's this one:
http://www.mlcswoodworking.com/shops.../speedcon.html

It actually uses a 40-amp 600-volt triac; ST partnumber BTA41-600B
Data sheet at
http://eu.st.com/stonline/books/pdf/docs/7469.pdf

I bet all you'd need to do is repackage this "15 amp" control using
a significantly larger heatsink for the triac. You'd have that issue
with any speed control you might build. It'd be easy to do with this
one because the triac is connected with wires rather than being
soldered into a printed wiring board.

Even if you do manage to zorch the triac, Digi-Key stocks this
part. It's $4.75 each in onesies.

Designing a close-loop speed control, particularly one for a
series-wound universal motor, would be a fairly ambitious project if
you don't have some familiarity with electronics and feedback control
systems.