Key on pulley works loose

[wildcatter]

check for a set screw in the bottom of the pulley groove.

[seal killer]

All--

There is no set screw to hold the key in place. But there will be when I reinstall it on the lathe. (There isn't one under the paint or in a pulley grove.)

0424231407.jpg (205.4 KiB) Viewed 1650 times

--Bill

[Harold_V]

Bill,
You might consider installing a second set, right on top of the key. The single set will permit the pulley to oscillate on the shaft as it rotates, due in part to the fact that the belts are not aligned with the pulley bore. With the two sets in place, the pulley should be rigid enough to resist movement, which, in turn, will prevent the key from walking. I suspect that's why it moved in the first place. I'm shocked to read that there was no set.

Belts will prevent a pulley from moving too far, but they won't prevent the key from walking. That's one of the reasons Woodruff keys are used.

H

[seal killer]

Harold--

Thank you. That is what I will do.

But we are off to the city for a few days . . .

--Bill

[liveaboard]

The pulley appears to be an extrusion; I measured the bore as 25.01mm
The other side and the sheaves are cut on a lathe. Odd is the 2 key slots.
The machine is 25-30 years old.

planer drive pulley Robland X31.jpg (63.01 KiB) Viewed 1604 times

[Harold_V]

There's a considerable difference between a sheave such as the one you show and the one used on Bill's lathe. With the belts mounted directly over the bore, the pulley isn't inclined to have side forces that enlarge the bore as it rotates. I'm not suggesting that it's a lot better, but it certainly is better than the other condition, which is guaranteed to destroy both the pulley and shaft if they are not mounted such that they can't move.

In my opinion, it's the epitome of cheapness when a company stoops to such low quality construction. About the only thing I can think of that is lower would be where bastard fittings are used in components that are engineered to fail, so the owner of such equipment is held captive and blead dry by having to replace overpriced components that are not available except through their agency.

Set screws are not cheap, but they're a lot cheaper than the components in which they reside.

H

[seal killer]

All--

Two set screws should hold it.

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Thank you for the help.

--Bill