poly v belt problem

[romartin]

I am a newbie, I own a MKV, The poly belt pulley is slipping on the shaft. I have not dismantled the headstock yet, Does any one know if the pulley is attached by a shear pin or set screw which may have failed?

[Nick]

Most likely, the belt is not tensioned correctly. See http://www.shopsmithacademy.com/SS_Arch ... _Belts.htm .

With all good wishes,

[romartin]

Thanks nick, I checked out the link, it gave me the info to explore further, the pulley is held in place by a set screw. I would not have found that without the info to remove the spindle.

[charlese]

Thanks nick, I checked out the link, it gave me the info to explore further, the pulley is held in place by a set screw. I would not have found that without the info to remove the spindle.

Whoa back there horse! Not that I have a desire to keep you from taking apart your headstock - BUT! Nothing but the belt cover has to be taken off to adjust the Poly-V-Belt. You only have to loosen the bolt - shown in Nick's video and rotate the eccentric bushing (with a screwdriver) in order to tighten the belt.

P.S. I assume you only want to tighten the belt, not replace it. One work of warning! Be careful not to overtighten the bolt and screw that tightens the headstock casing around the eccentric bushing. Some folks have done this and broken off one of the wings from the casing. This is disastrous, as it requires a new case.

[romartin]

I picked up on the "disasterous" overtightening part in the video. I did have to remove the spindle though because the gear/pulley which the polyv belt rides on is secured in place with a set screw which had advertantly loosened during op's. Problem is solved, thanks to guys like yourself and of course nick.

[billmayo]

I have found a few customer headstocks where the Poly-V pulley turned on the Drive sleeve shaft that required headstock repairs. I repaired a 98 headstock this week for a different problem that the pulley and shaft are now a one piece casting eliminating the set screw. I always check this set screw when replacing the Poly-V belt or rebuilding a headstock. I use blue LocTite on the set screw now to insure it does not untighten. Over tightening the Poly-V belt can cause the drive sleeve and idler shaft bearings to run hotter than normal. Be sure to check that the Poly-V belt is aligned between the 2 pulleys by moving the idler shaft until they are aligned as this can make the bearings run hotter too.

Bill Mayo

I picked up on the "disasterous" overtightening part in the video. I did have to remove the spindle though because the gear/pulley which the polyv belt rides on is secured in place with a set screw which had advertantly loosened during op's. Problem is solved, thanks to guys like yourself and of course nick.