running keyed shaft in bushing

I have a length of 3/4 keyed shaft I was going thinking of running in bushings
any thoughts on if the key slot will tear up the bushings?

im expecting 50-200lbs on the axle, 4 bushings each an inch long of a hard plastic
I can tack in a key and turn it down for bearing spots but seems overkill

Ball-bearing pillow block

Does a bear shit in the woods?

That is the wrong metaphor, but anyway, the plastic will probably not last long. The reason is that when a shaft rotates it presses unequally on the wall of the bearing seat, but the lubricant changes pressure to equalize the force. This allows the shaft to float without rubbing. If there is a slot in the shaft, then the lubricant will not be able to equalize pressure.

If you can't do bearings, I'd sleeve the shaft in way of the bushings or fill in the key like you suggested, especially in plastic bushings. I don't think it's overkill.

dz32 said:

I have a length of 3/4 keyed shaft I was going thinking of running in bushings
any thoughts on if the key slot will tear up the bushings?

im expecting 50-200lbs on the axle, 4 bushings each an inch long of a hard plastic
I can tack in a key and turn it down for bearing spots but seems overkill

Click to expand...

Yes, bears do shit in the woods. Or pretty much anyplace else they see fit. Who would presume to interfere?



Underkill, not overkill.

I use hand-trucks not so different with Oilite Bronze and don't expect forever-life. "Hard plastic" may have a short life, regardless @ 200 lbs?

"Place" a key, turn it flush.. and then.. the wise also hard-SLEEVE the buggers.

You know the ones. Uber-finely finished surface. Hardened. Sold for instant bearing fits when doing shaft repairs. Not cheap, either, sadly.

Which is exactly what you need if a "plain" bearing is going to have a life. You WILL still need that keyway filled, though. Cheat on that, learn a second lesson.

First lesson being why it can be cheaper to use plain shafting and only cut a keyway where it needs to be! Sometimes not at all?



Otherwise, "per earlier advice".. Chinee pillow-blocks with tolerable-decent AND "self aligning" roller bearings WITH decent eccentric shaft locks can be had for under ten bucks?

Here's a pair, US shipper:

UCP24-12 Pillow Block Bearing 3/4" Bore 2 Bolt Solid Base (2PCS) 7997894638 | eBay

Cheaper yet, you take four at a go. Under $20. Five bucks each?

I'd not mess with making anything but a couple of bolt-holes, meself.

And did not, last go. 1 1/2" Thompson shaft, full-length keyed, as-had. Two pillow blocks. No problem. Didn't really justify Swiss or German made ones, etc.

that all makes sense. I am mating up to an existing unit with the plastic bushings. Was trying to take the quick way out using a keyed shaft, looks like I will just scrap that and mill my own key way only where required.

Glad I checked in!

thanks guys, appreciate the insights.