Shopsmith Forums

This past summer I acquired a Mark V unit built in 99. It had been used very little by the original owner before he passed away and it was given to a neighbor. That neighbor also used it a little before I bought it this summer. Upon receipt I went through the entire package and other than a missing nylon connector for attachments I don't have, it was all in excellent condition.

With that all having been said I've been using the machine mostly as a lathe and it has served me well in that capacity. One issue I have been having though is that while it runs smoothly at slower speeds, once I try to take it up higher the headstock starts to shake as the project turns. I've tightened everything I can on the entire frame and rails but once I try to spin it up to approx more then half speed it starts to shutter and impacts upon my ability to turn. The same happens when I try to use the saw feature as well as the large sanding disk. It's not a matter of an unbalanced turning project.

Any help/guidance would be appreciated.

Belts!

Tension?

Have they taken a 'set'? Get some automotive belt dressing.

Last resort, replace them.

I'm not sure what you mean by "have they taken a "set"?" but I thought I had already tensioned the belts according to the instructions but I'll have a look again. They appear to be in great shape but for the cost of new belts I'll look at replacing them.

Rubber belts when under constant tension for a long period of time will assume the shape it is in and will resist reshaping. Thus the portion over a pulley will assume a round profile while the length between pulleys will assume a straight profile.

When the belt is subsequently moved, the rounded portion acts like a bump. As the belt is moved, the bump(s) cause vibration.

Belt dressing helps to remove the bumps as it 'softens' the belt.

Ah, now that makes perfect sense. Thanks so much. Looks like I have a bit of tinkering to do.

He said that he had been using the machine as a lathe. The issue then seems to be during operations performed only at higher speeds. If belt set is the cause, just turn it on and let it run at a lower speed for ten minutes or so. This should remove the set if there is any.

I'm thinking the lathe project might be mounted wrong or is offset.

He also mentioned having the same issue with the saw blade and sanding disc.