Timing Pully Fit On Servo Motor

[RJS100]

Quick question. Just putting a timing pulley on a servo motor. The fit was ordered as an h7.

When I slip the pulley on the shaft, it goes on about 3/8" and then hits what feels like a hard stop. See attached. I see it marking the shaft where it stops. I have never done this before and do not want to force it. Any tips on getting this on. I very very lightly sanded the pulley and shaft with 2000 grit paper to make sure there were no burrs.

Thanks... Richard

[RJS100]

SOLVED.... I hard to give the key a good solid tap!

[RJS100]

BTW....Are you supposed to put grease on these?

[ShawnM]

No, you are supposed to put Loctite on them.

[RJS100]

Really... Loctite on the shaft? How would you remove it.. Or adjust the height?

[cncsnw]

If the shaft key fits snugly, and has a set screw bearing down on it, then I do not think there is any need for Loctite.

I do cringe at the notion of giving a servo motor shaft "a good solid tap". Remember that your encoder is probably firmly clamped to the other end of that shaft, and is a delicate instrument. If you need to press the shaft key deeper into its keyway, try squeezing with a vise or clamp, or a pair of Channel Locks with some wood to pad the jaws.

[RJS100]

Thanks. It was really just user error. The last servo motor I worked on, the keyway was press fit and would not move. On this one, I just squeezed it with a simple plier and all is good. Not sure why I said "solid tap" earlier.

The shaft key does have a set screw bearing down on it. There is another set screw as well.

Thanks as always for your thoughts.

Richard

[ShawnM]

I use Loctite on all my motor shafts and pulleys, even the ones that have keyways. Once I know where it goes I use 648 Loctite on it. It’s easily removable with just a little heat on the pulley but I’m not sure why you’d need to remove it unless the motor fails. Many Z axis assemblies use a clamping collar without a key way and those surely need Loctite on them. Most people only think there’s rotational slip (a key way helps with this) but there’s axial slip as well. It may be overkill for an extruded aluminum hobby machine but with high torque motors moving a gantry that weighs a few hundred pounds, it’s necessary. Your mileage may vary.

[tblough]

I usually bore my pulleys out and use Fenner Trantorque keyless bushings: https://www.fennerdrives.com/trantorque/

[cnckeith]

Really... Loctite on the shaft? How would you remove it.. Or adjust the height?

the proper type of locktite! here is the stuff. https://amzn.to/3SYd5fb