Backlash Problems with the Phidgets geared stepper motor

Help & Support Robot Parts
1

robotshop.com/productinfo.aspx?pc=RB-Phi-132&lang=en-US

I’m using these geared steppers to build a SCARA robot arm. Unfortunately, I did not take into account the geartrain’s backlash (~1.8° !!) and it was very inaccurate!

Because the load on the arm is low, and the travel of each joint is ~180 degrees, I tried using the spring from a chainsaw’s pull-start to pre-load the motors to one side. This seems to work, but I need to find a stronger spring.

The joint is between two 60mm square plates 5-10mm apart. There’s a mounting hub 26mm dia to go around.

  1. Can anyone suggest a good source of springs for this?

  2. Can anyone suggest another method for removing the backlash here? I’d like to get the arm joints repeatable down to 0.1°.

2

Mr. Trick, I am building an automated microscope using the Phidgets stepper motor controller and Hayden Kerk steppers. Have you found a good solution for backlash compensation? Have you written code to adjust or counter-move the motor?

3

Unfortunately we do not have a selection of springs, but you might try McMaster-Carr. If we can think of any alternatives methods to reduce backlash, we’ll post it here.