JPG had suggested it might be due to shaft wear vs. a bad bearing & I promised to report back when my new idler shaft assembly arrived and I had the headstock apart. It came today and the problem does indeed appear to be shaft wear. When I pulled the idler assembly the old outer bearing slid off the shaft and remained in the eccentric (see photos below). Note in the third photo how the drive hub set screw had gouged the old idler shaft suggesting the shaft might have been too soft. This gouging has not occurred on the upper output shaft where its drive hub attaches.
After I replaced the idler assembly a chirping noise I had noticed at 500 rpm went away. Also, several months ago I mentioned a rattle I was experiencing when I started up my PowerPro in saw mode. The rattle did not not occur when the jointer was attached. Replacing the idler assembly got rid of the rattle. Apparently attaching the jointer (to the idler shaft output) stabilized the worn idler shaft enough that the rattle did not occur.
I still don't know why my PowerPro motor is noisy when run standalone (https://youtube.com/shorts/yr1BNapFLAs?feature=share) but a helpful TeknaTool support person reviewed the video and assured me that it wasn't a problem unless the motor started to lose power so I'll just live with that for now.
- Matanuska
Old & new idler assemblies.jpg (156.99 KiB) Viewed 16828 times
Attachments
Old bearing in eccentric.jpg (125.37 KiB) Viewed 16828 times
Worn idler shaft.jpg (112.13 KiB) Viewed 16828 times
- Matanuska
1984 Mark V upgraded to 520 PowerPro. Shopsmith cast iron table bandsaw, jointer, belt sander, and 60's vintage 610 jigsaw SPT's. Makita 2040 15" planer, JessEm Mast-R-Lift II router table.
I think SS should credit thee with the cost of the new idler shaft. Looks defective to me!
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
I sent an e-mail to Shopsmith Support asking if this was a defect and received a reply from Jim McCann who advised my idler shaft assembly was not defective, just worn out. He said the idler shaft is not hardened like the drive shaft above it. He noted that while the upper hardened shaft has a slanted flat for anchoring the set screw for its hub, the lower shaft flat is not slanted and the softer shaft allows its set screw to dig in for a more secure set. I'm not sure why they designed it that way unless it has something to do with the way the grooved pulley hub is attached to the idler shaft.
- Matanuska
1984 Mark V upgraded to 520 PowerPro. Shopsmith cast iron table bandsaw, jointer, belt sander, and 60's vintage 610 jigsaw SPT's. Makita 2040 15" planer, JessEm Mast-R-Lift II router table.
I know it's probably hard to determine with all of this damage to the bearing seat portion of the shaft... but what is the condition of the two ball bearing assemblies? I'm having a hard time rationalizing the shaft damage unless it occurred subsequent to one or both bearings failing. I just rebuilt a PP Idler, there was no discernible wear or damage on the bearing seats under the old bearings and both were a 'press fit' on both removal and installation. Everything was as I would expect.
The inner bearing appeared to be fine. The bearing portion of the loose outer bearing also looked good but I can’t confirm the ID was in spec.
- Matanuska
1984 Mark V upgraded to 520 PowerPro. Shopsmith cast iron table bandsaw, jointer, belt sander, and 60's vintage 610 jigsaw SPT's. Makita 2040 15" planer, JessEm Mast-R-Lift II router table.
In the youtube video, the play is between the inner race and the shaft.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
Yes. I suppose I could measure the shaft OD of the new assembly and compare it with the old shaft OD as well as the ID of the old bearing inner race. I suspect the wear is on the shaft.
- Matanuska
1984 Mark V upgraded to 520 PowerPro. Shopsmith cast iron table bandsaw, jointer, belt sander, and 60's vintage 610 jigsaw SPT's. Makita 2040 15" planer, JessEm Mast-R-Lift II router table.
Matanuska wrote: Tue Mar 24, 2026 4:52 pm
Yes. I suppose I could measure the shaft OD of the new assembly and compare it with the old shaft OD as well as the ID of the old bearing inner race. I suspect the wear is on the shaft.
Why?? Does the shaft turn "inside of the inner bearing race". If the assembly was done right in the beginning that would not happen. Is that the conclusion???
"Making Sawdust Safely" Dusty
Sent from my Dell XPS using Firefox.
Here is a disassembly picture of the one I rebuilt. I do see some loss of the finish (black oxide, I think) on the bearing seats but I think the pattern suggests that it occurred during bearing installation and removal. I don't think there was any real loss of material from the bearing seats on mine. This was a few weeks ago and I had bought into the theory that the OP's wasn't correctly hardened at the time, so I might not have looked as closely as I would now.
Idler Disasembled PP Comp.JPG (321.31 KiB) Viewed 12955 times
