Burning Rubber Smell from Poly V belt

[psdiegel]

Hi Folks! I hope someone can help me. I've been having a problem turning down the speed dial on my Shopsmith. The dial turns up easily but becomes very hard to turn when dialing down the speed. I oiled the sheaves but when I tried to turn the speed up and down to distribute the oil smoke started to come out and had a strong rubber smell. It seems as though it is coming from the poly V belt. It looks like one edge of it is rubbing against the metal shaft. I've read that the poly V belt on my version should ride starting in the third groove over but it looks like mine is in the fourth groove. Anyone know why the belt moved and how to fix it? I tried loosening the eccentric bushing but there wasn't enough slack to move the belt over to the correct location.
My Shopsmith is from around 1980.
Many thanks for any input you may be able to offer.

[JPG]

Easy up, stiff down is 'normal'. Slow towards slow is recommended.

Did you oil both the control sheave(on the idler shaft) AND the floating sheave (on the motor shaft)?

Did you rotate the eccentric til the slot pointed down(6-oclock?).

Also is the idler shaft/bearing/eccentric installed correctly?(flush with the casting)

Some differences of 'opinion' exist re the belt positioning on the drive sleeve pulley. None include the 4th groove. The important thing is that the belt aligns with the idler pulley.

[psdiegel]

Thank you for your response. Yes, I did oil both sheaves. I can see from a visual inspection that the idler bearing is NOT flush with the casting. If fact the idler bearing seems to be protruding about 1/4". Now I wonder if this may be the root cause of the poly-V belt becoming misaligned and rubbing against metal. So, the question becomes how to get the idler bearing back into the proper position. Is it a complicated process or is it an easy fix? Any thoughts or suggestions would be greatly appreciated.

Paula

[paulrussell]

Paula,

You would be well advised to watch this video, as well as the rest in the "Shopsmith Reborn" Sawdust Sessions videos:

Shopsmith Reborn Part 3: Drive Train
https://www.youtube.com/watch?v=OFvYrHUs7zM#t=16

List of all Sawdust Sessions videos (IMHO all are valuable for the new Shopsmith owner)
http://www.shopsmithacademy.com/Sawdust_Sessions.htm

[psdiegel]

Thank you, Paul! That video is just what I needed. Things are much clearer now. I think I'll be brave and give it a go. Wish me luck.

[psdiegel]

Yay, I fixed it! Thanks again for your help.

Paula

[dusty]

Good. I am sure we are all pleased to hear that. Now tell us what was done to "fix it".

[psdiegel]

The reason that there was smoke and a burning smell coming from the poly-v belt was that the idler shaft was no longer flush with the eccentric bushing. It was protruding out about 1/4 of an inch. This caused the poly-v belt to rub against metal. Here is the fix:
1.Took the machine up to fast so that the upper sheaves were wide open.
2.This allowed removal of the drive belt from the bottom sheaves.
3.Removed the screw and washer holding the eccentric bushing in place.
4.Removed the bolt and nut completely from the ears holding the eccentric bushing in place.
5.Turned the slot in the eccentric bushing to the 6:00 position. This allows access to the allen screw from underneath and between the ears.
6.Used a 5/32 allen wrench to loosen the allen screw.
7.Now, while holding the drive belt up and away from the upper sheaves, I gently tapped the idler shaft back until both the eccentric bushing and the idler bearing were flush.
8.Retightened the allen screw just until it was snug. Don't overtighten.
9.Replaced the bolt and nut and turned slot in eccentric bushing until poly-v belt deflected between 1/8" and 1/4". Tightened bolt until snug.
10.Replaced the retaining screw with a slightly larger washer that not only holds the eccentric bushing in place but the idler bushing too.
11.Put the drive belt back on the sheaves. Turn by hand several times to allow belts to seat themselves. Turned on and took up and dn several x.
Please note that my Shopsmith is from 1981.

[paulrussell]

Glad it all worked out!

[dusty]

The reason that there was smoke and a burning smell coming from the poly-v belt was that the idler shaft was no longer flush with the eccentric bushing. It was protruding out about 1/4 of an inch. This caused the poly-v belt to rub against metal. Here is the fix:
1.Took the machine up to fast so that the upper sheaves were wide open.
2.This allowed removal of the drive belt from the bottom sheaves.
3.Removed the screw and washer holding the eccentric bushing in place.
4.Removed the bolt and nut completely from the ears holding the eccentric bushing in place.
5.Turned the slot in the eccentric bushing to the 6:00 position. This allows access to the allen screw from underneath and between the ears.
6.Used a 5/32 allen wrench to loosen the allen screw.
7.Now, while holding the drive belt up and away from the upper sheaves, I gently tapped the idler shaft back until both the eccentric bushing and the idler bearing were flush.
8.Retightened the allen screw just until it was snug. Don't overtighten.
9.Replaced the bolt and nut and turned slot in eccentric bushing until poly-v belt deflected between 1/8" and 1/4". Tightened bolt until snug.
10.Replaced the retaining screw with a slightly larger washer that not only holds the eccentric bushing in place but the idler bushing too.
11.Put the drive belt back on the sheaves. Turn by hand several times to allow belts to seat themselves. Turned on and took up and dn several x.
Please note that my Shopsmith is from 1981.

Thank you very much for detailed explanation of the "fix". Everything that you did seems appropriate and well thought out. I know you have probably already done this but just in case - inspect that poly-v for excessive wear where it was rubbing.