Please Help, build homemade servo driver.

[arwinasis juno]

Hi..
I Plan to Convert my Milling Machine into CNC Milling Machine.

My Milling Machine spec. are :

drilling / milling cap.: 32mm, face milling cap.: 63mm,
spindle to table: 450mm, spindle speed: 80 – 1.250 rpm,
table size: 240 x 800mm, table travel: 175mm & 400 mm.
motor power 0.75 kw., power line: 220v 50 Hz

I Plan to use SERVO MOTOR CNC System, since it can hadle variable load and close loop.

Further, I plan to build it homemade:

using available DC motor such as automobile wipper motor,
starter motor, or other DC motor.

using inside component of broken computer-mouse as a
rotary/rpm/position/klik detector/sensor, attached to the motor.

I need help to build electronic circuit of SERVO DRIVER (DC)
which using rpm detector above.
Anyone has experience build this? or can just show me relevant link?

Thanks.

(this is maybe difficult but I'll enjoy the challange.
precision is sacrified)

[NC Cams]

It doesn't get much cheaper or easier than this as far as a DIY servo control:

http://www.uhu-servo.de/

This link should get you going. There is also a thread elsewhere on this message board regarding this project that has notes and FAQ's and tech feedback.

BTW, the mouse idea should be reconsidered. Reason: speed of mouse vs speed potential of DC motor.

The fets in the project above won't switch 250vdc if I recall. Might want to drop down to something more common to lower voltage DC. Study fet specs and consider power supply carefully if you improvise and BE CAREFUL.

Do NOT use a starter motor - way too much current draw and torque. These can get violent when you hit them with 12vdc.

Keep in mind that some motors are designed (internal brush timing) for unidirection motiod. Thus speed is NOT the same for same voltage at different polarity - this poses real control problems.

Don't skimp on preciseness. When you start moving iron so it can cut metal, stuff can break and people can get hurt in the process.

I'd look for surplus servos with fitted encoders before I tried to craft up something myself. It is way to easy to overwhelmed trying to engineer everything (drives, belts, ball screws, power supplies, software, limit switches, etc)....