Grey SS scroll saw stroke/vibration reduction

[paulrussell]

A while back I noticed that the stroke length specification had changed from 1 3/32" to 7/8" inch when the Teal model was released. This is true for both SS-mounted and stand-alone versions.
I also noted, anecdotally, that the people who had the Teal version described much less vibration than I was experiencing, even after a complete rebuild.
Recently I saw a Teal saw being parted out and bought the drive shaft/counterweight assemblies -- which are responsible for determining stroke length. As you can see, indeed the drive offset on the newer assembly is closer to the rotational axis. In other words, it doesn't move as far. And thus less vibration.

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I did have to do a little finessing to keep them from rubbing against the saw housing.

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There is definitely less vibration at all speeds. It also follows that the cut will not be quite as agressive since fewer teeth are pushed past the wood at any given speed.
I did vibration measurements at all 10 speeds using a phone app, and tomorrow I plan on repeating the tests with the new drive cams.

[reible]

Are you saying these parts might be interchangeable? I really don't love my old gray saw but this might change my mind if that is the case.

Ed

[paulrussell]

Are you saying these parts might be interchangeable? I really don't love my old gray saw but this might change my mind if that is the case.

Ed, yes, with one minor adjustment. The counterweight bearing shoulder (circled) is a larger diameter on the newer part and did not quite clear the bearing seat of the base casting. I first smoothed the opening in the base (pic in original post). I then mounted the counterweight shaft in my lathe and at a very slow speed filed the alloy shoulder to fit. It did not require much.

I did put a 1/2" ID spring washer on each axle to remove lateral play -- If I recall properly, later saws have a washer from the factory.

As far as the improvement: it was immediately noticable, but not earth shattering. Unfortunately my vibration measurements with the phone app have proven worthless, but I can say I was able to comfortably make cuts with the speed set to 10. Before the parts swap I hated anything over 6.5. Personally, it was worth the time and money. I paid $30 each for the parts (used). They are $37 each from Shopsmith.

BTW the new parts weigh less than those from the gray saws, and the counterweights have a different geometry. I would think it iffy at best that replacing only the "drive shaft" would work.

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