Messages

1

General Mach Discussion / Re: Placing the Encoder - On ballscrew vs On motor

« on: February 03, 2008, 06:21:58 PM »

I thought that the back-forth hunting of the motor would most probably happen if the glass-scale output is used to provide positional feedback. My thought is to relocate the rotary encoder, normally located on the servo motor, on the ballscrew itself.

2

General Mach Discussion / Placing the Encoder - On ballscrew vs On motor

« on: February 03, 2008, 06:11:06 PM »

Hi all,

I am in the process of retro'ing a manual machine using a package from www.lowcostcncretrofits.com, powered by Mach3. I am at the stage of interfacing the servos on the ballscrew. A lot of people go with the timing belt reduction way. I tend to like the gearhead way. Truly accurate reduction gearheads are also extremely expensive (in comparison to timing belt reduction systems). Cheaper gearheads can have an angular backlash of up to 40arc-minutes.

This is what I am thinking.

If I do get a cheaper. higher-backlash reduction gearhead and relocate the encoders away from the motor and directly onto the ballscrews themselves, wouldn't that make the high gearhead backlash a non-issue ? Regardless of the backlash on the motor-gearhead interface, if the screw don;t turn then the encoder does not register.

What do you guys think ?

Regards.