Scroll Saw Won't Hold Tension Under Power

[algale]

A little over a year ago, I purchased a used Shopsmith scroll saw (teal colored, Mark V mount).

I have used it very little, but when I have, I have always been disappointed with my ability to follow a line -- straight or otherwise, which I attributed to possible lateral movement of the arms.

Today, however, I noticed that what is actually happening is that the tension cam/lever at the back of the top arm begins to rotate counterclockwise, de-tensioning the blade, shortly after powering up, even though the cam/lever is in the down position. This rotation causes the blade to go partially slack and once that happens, it is almost impossible to follow a line because the blade moves backwards, left and right almost to the extreme limits of the hold down.

If it makes a difference, I was running at between R & S speed on the headstock (max speed for the blade and thickness I was cutting is listed at S in the manual).

Also my usual procedure for tensioning a new blade is as follows: After locking the blade in the lower and upper blade holders (with both front quick release tension cam and rear tension cam/levers in their detensioned positions), I lower the rear tension cam/lever and turn it clockwise until the blade has no slack and is almost fully tensioned; then I flip up the front quick release lever to bring the blade to final tension. I try to get the blade almost to the point of popping out of the holder. Sometimes it does pop out on start up and then I back the tension off slightly using the rear cam/lever until the blade will just stay in.

Any ideas on how to solve the problem of the rear tension cam/lever rotating on its own and releasing blade tension when under power?

Thanks,

Al

[jsburger]

I don't have an answer Al but it will be interesting to find the solution. My wife has many many hours on her stand alone Teal scroll saw and has never had that problem.

[reible]

I have the older gray model with the updated release system which I think makes it more like the newer saw that you have. I have not had that happen.

I did just go out and look at mine, with the lever up it is easy to turn but when you "lock" it it can still be turned but it much more "stiff" if you will, but it still can turn.

I'm interested in what you find out as I will be taking mine apart and rebuilding it best I can soon. I have parts on order and the back ordered drill press lever kit is due in on the 18th so I hope everything ships soon after. BTW you can not get all the parts for the old gray model any more. It was order-able but a call let me know that they no longer have certain parts. It was left on our answering service so I did not pursue it any more and will have to see how things go when I start working on it. Might have to have a few things made or worse, lose the use of it. I do like the saw that Scott Phillips has........

Ed

[Bruce]

Since you bought this saw used, have you checked a parts diagram to verify that you aren't missing parts?

[algale]

Since you bought this saw used, have you checked a parts diagram to verify that you aren't missing parts?

I have not opened the cover that goes over the rear of the arms and the tension rod mechanism. The visible parts of the tension mechanism above the cover all appear to be there.

[JPG]

I would be suspicious of 38/39. If there is slop(caused by wear on the pin) as the rod moves up/down, the lever may acquire clearance that allows it to rotate.

I be suspicious since that was a concentrated wear point on my 'earlier vintage'.

[algale]

I would be suspicious of 38/39. If there is slop(caused by wear on the pin) as the rod moves up/down, the lever may acquire clearance that allows it to rotate.

I be suspicious since that was a concentrated wear point on my 'earlier vintage'.

Ugh. I was just looking at your refurb thread and saw that. It looks like I will have to crack open the case. What's the minimum I have to remove to get a look at that?

[JPG]

I would be suspicious of 38/39. If there is slop(caused by wear on the pin) as the rod moves up/down, the lever may acquire clearance that allows it to rotate.

I be suspicious since that was a concentrated wear point on my 'earlier vintage'.

Ugh. I was just looking at your refurb thread and saw that. It looks like I will have to crack open the case. What's the minimum I have to remove to get a look at that?

You will not like the answer!!

[algale]

I would be suspicious of 38/39. If there is slop(caused by wear on the pin) as the rod moves up/down, the lever may acquire clearance that allows it to rotate.

I be suspicious since that was a concentrated wear point on my 'earlier vintage'.

Ugh. I was just looking at your refurb thread and saw that. It looks like I will have to crack open the case. What's the minimum I have to remove to get a look at that?

You will not like the answer!!

Does that mean a total tear-down, like you did??

[JPG]

No, but

10,81,85 x 3
95,86,110 x 2
7,95 , 7,8


With the tension released, you should be able to detect any play by pulling up/pushing down on the rod.