X backlash / movement

[andym]

I have a PRS Alpha, I was having some cutting accuracy problems so have recently changed the pinion gears. It is cutting fine but I just have a question.

I have read that there should not be any movement of the X car when the rack and pinion are meshing properly and the motors are on but there is a little on mine.

I got the machine in 2008 and on the first assembly I noticed that when powered up there was a small movement of the x car. I took a motor off while still powered up and noticed that there was some movement when I tried to rotate the pinion by hand. I just assumed that this was normal and within tolerance.

Is this normal or do I have a problem with my Alpha step motors?

The amount of movement is very small (hard to measure) but it is movement all the same.

[Brady Watson]

Yes - a small, hard to measure, amount of movement is normal, provided the pinion is tight on the shaft. The backlash perceived is very small and in the gearbox itself. $399 will get you a brand new motor with a fresh gearbox - but the condition will eventually come back due to wear.

-B

[andym]

Thanks Brady, good to know.