Shopsmith Forums

Hi,

Not so sure how useful this information is but on the version of scroll saw I have the table is smooth (I'm guess this is earlier??). The blade mounting system used a "fixture" that held the mounting blocks. In my case the previous owner(s) had mounted this on the upper arm cover. (No idea if this was part of shopsmiths plan or not???)

The instructions call for installing one of the end of the blade so it touches the screw (#34 on my parts list). Then you remove that mounting block and slide the blade in to the other mounting block until it touched that same #34 part before tightening in place. So the fixture did not provide the correct distance between mountings.

Again I do not have nor have I ever used the table with built in fixture so I don't know how that works. But I think the distance you need is established by the #34 screws and if the blade is touching both of them you will not be getting any clunking.

I do know that I upgraded to the newer system and am glad I did. The little flip lever in front works like a charm. Don't know if it just me but the little hand tighteners seem to take a lot of force to make sure they are tight?? Anyway it works.

Ed

No Knocka, Knocka and no Knowa Why.

I decided to pursue the noise and at the same time compare the previous blade mounting method with the new improved method. I was actually thinking that maybe the length of the assembly was contributing to the noise issue.

Sure enough, the two are not the same in overall length. The pictures tell that story. Using the new (modified) fixturing, the overall length is "shorter".

When I put the old fixture and a blade in the scroll saw, tensioning was way off. Adjusted that and I had a smooth running scroll saw. No knocka, knocka. Hmmmm.

Put the other assembly (new fixture and a different blade) back in the scroll saw. Naturally, tension was again way off. Readjusted tension and turned that puppy on. Guess what. No knocka, knocka.

Got me!

I know it's been said before, but I just gotta sing the praises of ShopSmith's Customer Support and Linda. I called C.S. the other day about the Knocka-Knocka sound my Scroll Saw was making and to purchase a 4-spline drive hub so I could drive my new Strip Sander from the Quill side of the unit for chisel/knife sharpening. After ordering the hub, I asked Linda about the knocking noise and she said no, it's not normal. I told her I was careful to align the blade in the holders with the jig built into the back of the table. She asked if I was having problems with the blade pulling out, that some had. She said the recommendation was to ensure the blade was pushed all the way in and to the back of the holders. This would make the blade assy slightly shorter than indicated by the jig but that was OK, and that resolves the knocking noise.

On another note, I mentioned to her that I had just received my chisel sharpening attachment for the strip sander and had noticed that the rotation-warning label on the unit had been installed upside down (arrow pointing in the wrong direction). Linda's response... "Oh, you got one too? I just found out about that Friday. I'll send you a new label."

I sharpened my lathe chisels, and WOW, what a difference. I also made the knife holding attachment and sharpened a pocket knife and a 12" chef's knife with it. I did find an "issue" with sharpening the longer blade knifes, but found a work-around that works well. If anyone plans on sharpening long blade knives with the attachment, PM me and I'll share what I did to make it work well.

Having just completed a rebuild of a mid-80's scroll saw, I now have a good understanding of what can cause the upper arm to hit the cover.

I find it interesting that the PO had glued rubber bumpers on the underside of the cover! They showed signs of impact.

The lower arm is where the up/down motion is applied. It moves the bottom of the blade AND the tension rod at the back end. The tension rod does not connect directly to the upper arm, but does so through the rockers(upper and lower), the tension spring, and knob spacer. The spring tension is determined by the top position of the knob spacer. Screwing the tension knob in moves the spacer down and presses against the upper end of the tension spring which will become shorter and push harder against the upper rocker.

The separation distance of the two arms can vary when tension adjustments are made (the spring length changes). Thus the tighter the tension, the shorter the (the separation will vary with no blade attached or an untensioned one or one that stretches)upper/lower separation at the rear of the arms. The arms being quite rigid means that under tight tension, the blade end will try to move further apart(that is where the 'tension' to the blade comes from).

So: the only thing controlling the blade end separation is the blade(and its holders) itself!!!!!

If the blades are too long, or not inserted into the holder(s) far enough(to the screw), then the upper arm will be too far from the lower arm and could strike the bottom of the top cover. Adjusting tension should not change relative blade end arm positioning(unless tension is so loose that slop is being taken up).

All that assumes 'normal' parts.

The one I rebuilt had the tension rod-lower arm retaining pin severely worn and the hole in the tension rod elongated due to wear. That created quite a bit of slop at that point which I am sure was getting progressively worse.

It had to be making noise!! The slop would come and go as the lower arm pushed then pulled ... on the tension rod.

So there may be more than one knocka knocka source.

FWIW the tension rod hole/pin slop will allow the rear arm separation to cause the tension spring to expand(decrease tension) on the upstroke of the blade.

Appears to me the blade insertion tells the tale!;)