re:motor/leadscrew/ps recomendations and calculations

Richard wrote:

>I've built a prototype cnc router using 3/8-12 leadscrews, Dan's 2
>amp driver,<snip>
>The power supply is an old AT supply.
>I'm using half step mode, with 4800 steps per inch and CNCPro.
>I'd like to increase the speed, but still have at least 50 lb of
>linear force available.

Richard,

This is a GROSS simplification, but...
In steppers, Amps=torque, Volts=speed

Your amps are already limited(by the driver bd) to 2A.
Get that power supply up around 36V!! A 24V xfrmr with rectifier and
filter cap will 'put out' about 34V. Works fine with Dans board. you
MUST fan cool the LARGE heatsinks. And add a dropping resistor to the
input of the 5V voltage regulator IC, since it can't handle the 34 V
input. Dan can tell you the details...

>What I like about the AT supply is the readily availble 5v for limit
>switches, but I suppose I could pull 5v off Dan's board somewhere
>for the same purpose...

You have a 5v supply on Dans' bd. One of the 3 terminal 7805 versions
can source up to 1.5A. More than enough for limit switch pullups!
Check to see which version Dan uses and how much is 'left' after his
bd needs are serviced. You MAY need to replace this 30 cent part with
one rated for higher output. And maybe more heatsinking.

This is all simple stuff, even for a novice, so go for it!

Hope this helps.

Ballendo

P.S. I'd change the leadscrews TOO! But increase the power supply
voltage first and see where you're at...