Getting extra life out of your Z pinion

[blackhawk]

I recently swapped out my non-geared Z motor for a 10:1 geared version. While doing all the calculations for my unit values, I ran across something that I never realized.

Most all Shopbots have either a 20 tooth or 25 tooth pinion gear for Z. A 20 tooth pinion moves your Z rack 3.14 inches for every one revolution. A 25 tooth pinion moves your Z rack 3.92 inches for every one revolution. If you think about it, most people do 80% of their cutting over maybe a 2" range of Z travel. So, on a 25 tooth pinion, especially, you are wearing out only half the pinion.

Every few months, I am going to disengage my Z motor from the rack and then rotate it half a turn. This should help wear all the pinion teeth equally. Possibly giving me 1.5 to 2 times the life of the pinion.

[BigoleRob]

do your wearing pinions make odd whirring? or any other (hard to describe in text noises) mine are making some odd noises every once in awhile in the length of the track, other than just the sound of the electric drive motors.

[blackhawk]

Robert - Check your rack and pinion and be sure there are no wood and/or metal chips in the teeth. I once had a small sliver of metal come off a tooth that was causing some roughness in my Z axis. Didn't make a whirring noise, but had a rough spot that you could feel by hand.

Also, make sure your setscrews are tight.

[johnbrophy]

Robert - Check your rack and pinion and be sure there are no wood and/or metal chips in the teeth. I once had a small sliver of metal come off a tooth that was causing some roughness in my Z axis. Didn't make a whirring noise, but had a rough spot that you could feel by hand.

Also, make sure your setscrews are tight.

How did you remove the z motor? I am trying to replace the pinion but i don't see a way to get the motor off without disassembling the whole z-car.