Servo motor question

[jeep534]

I am starting to retrofit a Lagun cnc mill I have looked at the gecko 340 drive. The documentation suggests that the encoder should be connected directly to the motor. On my mill the encoders are hooked to the end of the ballscrews and the ballscrews are belt driven. I have posted some photo's under hobbies at http://jeep534.smugmug.com
I was just wondering what other people are doing. I plan to useMach3 to control this machine.
Happy Hunting
archie =) =) =)

[NC Cams]

Assume you have 2000 count/rev encoder and 0.200 per rev lead screw. Thus, you have 1 count per 0.001" table travel (the encoder won't deal with backlash induced lost motion, only rotation of the screw).

If you have a 2:1 drive ratio and hook it to the motor, (enter sound of caclculator use here), you now have 1 count per 0.0005" BUT you now have some slop potential in the drives (not much usually).

It can be done either way. It all depends on the resolution you're looking to achieve

[Geof]

Originally Posted by NC Cams Assume you have 2000 count/rev encoder and 0.200 per rev lead screw. Thus, you have 1 count per 0.001" table travel.....

Um... 0.200"/2000 = 0.0001"

[NC Cams]

Geof: sorry for the dyslexic fingers.

Although the magnitude is off by a factor of 10, the rest of the post remains the same.

[Geof]

Those mistakes are okay in print; the embarassing times are when you give one of your guys instructions with a similar mistake and then berate him when something doesn't fit! Ooops.