Speed Control function

[DLB]

PEX is excellent but requires some investment in the special clamping tools. The clamps are checked with simple Go/No-go tests. Water stays much hotter in the pipes and they are much less likely to freeze. I have fixed three under-slab hot water leaks by running PEX in the attic after paying a plumber almost $2K to do the first one in copper under the slab. (He was the one that advised PEX in the attic if the problem recurred.)

Back to the OP's subject. If you turn the speed control knob, say from "A" to "B" and you can see the Floating Sheave on the Motor shaft move in response, then I think the speed changed because the pulley has to be in a different part of both grooves. At these low speeds sound does not change very much. The open question would be, did it move enough? Answering some of your earlier questions:

The lower belt is effectively tensioned by the speed control system when everything is working right. Basically the motor sheaves are going to reposition to balance the coil spring on the front of the motor with belt tension. Only the upper belt needs to be manually tensioned. When JPG asked if it was tensioned, I think what he was getting at is that sometimes the sheaves don't operate correctly and the belt loses tension. In this case, going from slow to a bit faster, it would be the Floating Sheave not moving freely on the motor shaft to maintain tension and go faster.

At low speed your belt should be near the outside of the Idler Sheaves. At high speed, the belt should be near the outside of the Motor sheaves. Nominally, that is about 1/8 inch in from the outside of the sheaves and equal in each case.

If it were me, I'd take the motor off, remove the Floating sheave, and thoroughly clean the motor shaft, key, and inside of the sheave. You don't need an apron, but be very careful when removing the spring as it is under some tension. Ideally, one person compresses and controls the spring while the other removes the snap ring.

-David

[JPG]

What is wrong with one hand compressing the spring(using a bored board if necessary) and the other hand removing the retaining ring?

[SSWoodwrk7]

Back to the issue at hand... I did take the cover off and watched it operate. Yea, I'm livin on the edge!!! Both sheaves come together and separate simultaneously. There is about 3/4+- play in the belt. It is a shopsmith belt in good condition. Do different headstocks take different belts? Is it possible that it has the wrong belt installed? Based on the condition of the belt I can't imagine it stretched.

[JPG]

All Mark 5 and Mark V use the same motor belt. Mark VII belt is longer.

[DLB]

Play in the lower belt is subjective because of the floating sheave and spring. I'd say mine has much less, but I can get to 3/4 by pressing harder. As long as it is not visibly flopping while running and the sheaves are responding to speed changes I'd say it is okay. And if it is loose the likely contributors are the spring itself and how freely the sheave slides.

On my headstock, I measured the change in floating sheave location from "Slow" to "G" at .380, slightly over 3/8 inches. I measured it from the inside on the washer at the end of the motor shaft to a flat spot on the pulley.

While doing that I asked myself how I know the speed is changing on my SS. Unlike higher speeds, there is not much change in sound/vibration over the speed range we are talking about. I know mine works because with the bandsaw installed it is somewhat noisier and I can again hear the speed changes. After thinking that through I want to restate the original problem as 'OP reports there is no discernible change in speed over the range from "Slow" to "G." ' Then I want to ask if it is possible that you are experiencing a speed change but it is masked by the lack of audible feedback? And if not, how are you determining that the speed is not changing?

One way to check: I held a plastic pen against a spindle at the flat while running. I could both hear and feel the speed changes.

- David

[JPG]

From A to G the speed only doubles(700 to 1400).

[SSWoodwrk7]

So here's the deal. I own 2 Shopsmith 510s. The one I use daily I can audibly hear the increase in speed from slow all the way up. The one I recently purchased i can't hear the increase until around F or G. So I took your advice and held a pen on the spindle as I increased the speed and to my surprise I did hear the increase. And I am very glad I did. No more problem. Thank you all for your input and advice.

So now I'm beginning to think maybe it's time for me to break down the headstock on my daily use machine and oil it up since it seems to be a bit louder running machine.
Again, thanks for the help.