New Pinions, how snug should we be?

[jTr]

New pinions, feels much tighter, but wondering precisely how much play should be there. Using a dial indicator, I've got a .003 to .004" movement in total, pushing back and forth. With a bit more gusto, one of the X drives does go closer to .008, but that's putting my shoulder into it, going past the expected "click" of the gear reduction in the motor. That one does seem a bit spongy compared to the other side. Removed, re-checked grub screws for tightness and used a pinch of help from a quick-grip clamp to assure gear is snug to rack. FWIW: that is the side who's rack was bent in shipping, which necessitated removing/replacing the 3M trim tape underneath, as it had shifted sideways, about .25" out from rail.

Are these acceptable tolerances, or is some backlash adjustment needed in the motor housing?

(Machine is 3 years old, and I've neglected to replace pinions until now...:o Lots of fresh grease and marked my calendar for next year's replacement)

jeff

[Brady Watson]

That's acceptable/normal backlash, which is mostly in the motor's gearbox. I wouldn't adjust anything inside the motor just yet...The reason there is backlash is the same reason you should warm up your car before mashing the pedal and doing a bonzai run - tolerances. As the motors heat up some of those gears are going to expand and soak up some of that backlash.

Grub screws should be cranked on until you almost bend the wrench. There should be loctite on them...blue is fine to use so you can get them out next time.

-B

[jTr]

Anyone on the fence about investing in a Shopbot, take note:

Left message with Nancy indicating who I was and that I needed a set of pinions for my bot, asking for a call back to sort out the details of the right parts. Before I knew it, I had an email with an invoice attached, asking that I email CC# back. Before I had a chance to do so, she called me directly in order to save me the time and expedite the order.
Three days later, the pinions were here, well packaged with grub screws pre-treated with blue Loctite. One hour later, machine was almost like new.

Now that's customer service!!!

Thank you, Brady
and thank you, Shopbot!

Jeff

[Brady Watson]

You're welcome. Glad you got it sorted out.

-B