Shopsmith Forums

How often should you replace the belts in the Mark V headstock? My 520 is almost 20 years old. I have no indication I have any belt issues but I am going to do some drive train maintenance so it would be convenient to replace the belts at the same time if necessary. Does shopsmith have any recommendations on belt replacement? Do forum members have any recommendations on belt replacement? I could only find the poly v belt part number 521681 but I could not find the other part number.

Thanks

Michael

I don't recall any set time to replace the belts. I have seen headstocks that were 20 - 30 years old and the belts looked good. Bearings should be replaced when they get noisy but the drive train in the headstock is noisy by itself and can cover up other problems. I don't do a lot of headstocks only about 30 to 35 at this time but all of them have needed the 6205 drive sleeve bearings replaced. If I have to replace the bearings on the drive sleeve then I would replace the poly V belt because I don't want to replace it later. I leave the motor bearings alone unless they are noisy.
In short use your own good judgment about what to replace. The last headstock I did recently was an older machine the a bunch of black crud ( a technical term) on all four of the sheave faces. It was powder from a dried out V belt that was severely dried out but this machine never received any maintenance.
Good luck
Bill V

would it be safe to say it would be like any other belt drive , that if it shows signs of wear or cracking replace it ?

Yes

In addition to physical condition of the Drive belt in general, when the belt measures less than1/2" wide across the flat outside section.

The narrower width allows the belt to ride too deep in the sheaves which affects speed settings since effective running geometry is changed and can even seize up in the depth of the groove.

Everett

Totally agreed.
My mark V had a narrower power belt, and cause the speed higher than nominal throughout the speed range.
Also, I had concerned that it might bind the motor sheave.

everettdavis wrote:In addition to physical condition of the Drive belt in general, when the belt measures less than1/2" wide across the flat outside section.

The narrower width allows the belt to ride too deep in the sheaves which affects speed settings since effective running geometry is changed and can even seize up in the depth of the groove.

Everett

Of the 8 headstocks I have worked on only one needed a replacement belt. The poly V had frayed, perhaps from not being in the right notches?? Now granted I don't know the history of the machines but they were mostly from the late 70's and early 80', much has to be said for how busy they were over the years and if adjustments and maintenance had been routine. In most cases the belts could be replaced if you already have the machine apart for other reasons and especially if you have had to take the belts off anyway and they are old.

Ed

In addition to fraying and checking, there is when it has stretched to the point the eccentric will no longer tighten it to prevent slipping.