Need advice on roller bearings for drum sander.

[7milesup]

Update:

Following your guys' advice, I found a couple of bearing suppliers about an hour away. I called both of them. One was not helpful, but the other bent over backward to help me out, along with educating me on bearings. The original bearings had an eccentric locking collar, but I was informed that a concentric one would be better for my needs. The eccentric lock could possibly introduce a very slight off-center position of the shaft within the bearing (I am assuming a thou or so?). I ordered two pillow block bearings from him with concentric collar locks that have dimensions very close to the originals. They should be here in a day or two.
As well as my sander has worked over the years, one problem consistently showed up: "chatter" marks in the boards. I attributed this to the bearings, but as I dismantled this machine, I discovered more issues. The biggie was my sandpaper take-up mechanism. I thought that I had it balanced (using material calculations) but when I took it off of the sanding drum and set it on an actual balancer, it was way off. A little time on my mill and some counterweights solved that issue. The final part of the vibration puzzle is the drive belts from the main motor. I decided to replace the standard v-belts with a segmented belt. Accu-Link belts. That system should be here in a day or two also.

 

[Ischgl99]

It sounds like the concentric ones are the type that use a tapered adapter sleeve to give a more rigid grip on the shaft. Those will definitely be better at higher speeds. The shaft tolerance can be up to 0.002” undersize for low speed applications, but you would want a tighter tolerance than that at higher speeds. For metric shafts, the tolerance is h6 to h9, which equates to +0/-0.0006 to +0/-0.002” for a 1.5” shaft.

This is the description of the adapter sleeve inserts in my Schaeffler bearing catalog.

 

[7milesup]

The drum is only spinning at 1166 RPM roughly, so not a high-speed application, but anything I can do to reduce vibration to a minimum is welcome. Below is a picture of what I will be getting.

 

[Iceberg86300]

The drum is only spinning at 1166 RPM roughly, so not a high-speed application, but anything I can do to reduce vibration to a minimum is welcome. Below is a picture of what I will be getting.

View attachment 451511

Kinda late, but just wanted to add:

Honestly, those are nicer all around. W/o set screws or eccentric ring forcing the shaft off center in the inner race you don't have to worry about shaft/race clearance induced runout. Instead, the only offset you have to deal with is that caused by the internal clearance of the bearing.

Also, b/c of how they operate, the eccentric locking versions self tighten & as such, are only supposed to be used in one direction of rotation, otherwise they can undo themselves. In your application they'd probably be okay as long as the set screws are tightened sufficiently.

Is that something you remember dealing with way back when? The shaft in the 1st photo looks like there might be some telltale race slippage damage, but if the shaft wasn't moved prior to the photo it would obviously be unrelated.

Anyway, for future reference for anyone that may happen upon this thread, the following is a wonderful resource regarding the different mounted shaft/inner race interface options:

Mounted Bearing Locking Collar: Which Is Best?


Sent from my SM-N975U using Tapatalk

 

[7milesup]

The shaft in the 1st photo looks like there might be some telltale race slippage damage, but if the shaft wasn't moved prior to the photo it would obviously be unrelated.

That is a good question. I somewhat remember that shaft not being in the best shape right from the get-go.

The rest of the story now... One of the new bearings was apparently defective right out of the gate, so I just got that swapped out. The machine certainly runs smoother.

Thanks for the link BTW.

 

[woodchucker]

I find it amazing that in that kind of service it needs replacement.

why, saw dust destroys many a bearing. My band saw bearings for wood on a USA made delta lasted only a few years. The saw dust can pack up a bearing, or gum up the grease and dry it out. Especially shielded, and not sealed.