Idler shaft too hot

[tucsonguy]

I just finished rebuilding my headstock, new bearings, belts, new motor sheave (broken) new button bearing (shattered). Got everything back up and running, but the idler shaft is running very hot. I did not replace the shaft or bearings, so I think its time to do that. I tried adjusting the eccentric bushing to take a bit of tension off the polybelt, no change. I can see a slight wobble in the sheave shaft as it turns at slow speeds. I'm thinking that either the bearing is bad, or the shaft or sheave slightly bent. Any other thoughts?

[everettdavis]

There is a set screw under the eccentric that Bill Mayo used to warn folks not to over tighten. It loaded up the bearings. You might back that off a tiny bit to see if it helps.

Read the Headstock Improvement Kit Document I posted in the Large Format Document page. It is on that page itself.

At Bill's request I added additional content he sent me in an email about that kit, and he mentions the setscrew, and even what kind of setscrew needs to be used.

Wear is wear, so if it is worn and wobbly, the setscrew isn't going to fix that, but it may prevent issues down the line once repairs are done.

Also be aware if you upgrade to the new style shaft, you will need the new split eccentric as the bearings are smaller than the original eccentric bearings.

Everett

[tucsonguy]

I have the newer eccentric bushing - no set screw.
But the older style shaft (one large double bearing.) This is how the machine came to me. They are a good fit, though... Do you think that may be causing the problem?

There is a set screw under the eccentric that Bill Mayo used to warn folks not to over tighten. It loaded up the bearings. You might back that off a tiny bit to see if it helps.

Read the Headstock Improvement Kit Document I posted in the Large Format Document page. It is on that page itself.

At Bill's request I added additional content he sent me in an email about that kit, and he mentions the setscrew, and even what kind of setscrew needs to be used.

Wear is wear, so if it is worn and wobbly, the setscrew isn't going to fix that, but it may prevent issues down the line once repairs are done.

Also be aware if you upgrade to the new style shaft, you will need the new split eccentric as the bearings are smaller than the original eccentric bearings.

Everett

[everettdavis]

If the sleeve is split and you have the new style bearings, you may be able to find them locally.

It is important that they stay firmly secured in the headstock, and Bill Mayo liked to install an oversize fender washer to retain the eccentric and the bearings with the screw at 12 o'clock relative to the shaft.

I know that Jacob Anderson is not fond of the new style idler shaft at all and says they wear out more frequently.

You can read more about that in the Shopsmith Bearings Guide I wrote earlier this year.

Hope that helps.

Everett

[tucsonguy]

The bushing on the machine is the newer style, it has no set screw but a tapped hole on the front, for a screw to hold it in place. It's split at 12 o'clock. But the shaft has the old style single piece double bearing. I'm wondering if these two pieces are not meant to be used together?

[everettdavis]

A picture is worth a thousand words....

Don't over tighten the tension bolt below. Easy to break off mounting ear.

If you use a split compression washer to lock, getting it to flatten out is just enough tension.

Everett

Eccentric variances.png (148.36 KiB) Viewed 8652 times

[tucsonguy]

Thx. Good info! Have ordered the correct bushing.

[everettdavis]

If you ordered the old eccentric and plan to use the original style (water pump style bearing set as some refer to them) please be aware, if the lubricant in the bearings has become dry, they will run hot no matter what you do.

If you find that is the case and you want to stay with that setup, I think Jacob Anderson may have some of the older shaft assembly setups that will work. You can find him at https://jacobs-repairshop.com/

Obviously you can acquire the new style idler shaft / bearing setup from Shopsmith directly.

Good luck, and please do post a follow-up when you complete the repairs. Others will benefit from your diligence.

Kindest Regards,

Everett

UPDATE: Bandsaw-Tire-Warehouse states they have new ones for sale on eBay...

https://www.ebay.com/itm/NEW-SHOPSMITH- ... 0022!US!-1

[everettdavis]

Just a note on Water Pump Style bearings:

The technical name would be Integral Shaft Bearings and they are lubricated for the mechanical life of the bearing.

Nick Engler, formerly of Shopsmith, once tried to press one apart without any success. The construction cross section illustrates why they are not serviceable at the end user level.

Everett

Water Pump Bearing Construction.png (66.5 KiB) Viewed 8551 times