Delta 15" scroll saw not cutting straight in the vertical plane

[Rob Miller]

My daughter and I decided to attempt to make some chess pieces using an old Delta 15" scroll saw I inherited from my father. Changing the blade from one hole to another was an incredibly frustrating task due to the antiquated allen screw clamp arrangement at top and bottom of the blade, but that's another issue. My main problem is in the cut itself. After cutting the perimeter of the first piece (1 1/2" thick, and the same width), I noticed that the cuts at the top of the piece were not identical to those at the bottom of the piece. There were two issues here. The first was that the outline of the cut at the top was consistent with the pattern we were using but when we flipped the piece over the lines did not conform to the same outline. That is, there appears to have been some drift in the blade but only at the lower end.

The second issue is that the cuts came out as if the blade had an arc in it. That is, on the vertical plane of the cut, one side of the piece was concave and the other convex. Does anybody have any idea what would cause this? Also, is there any sort of adaptation that could be made to an old Delta saw (this one's probably 20 years old) to eliminate all the fuss involved with replacing the blade in its clamp device? Seems like poor technology to me.

[Jerry Miner]

Rob---

I have an older Delta scroll saw, too---don't know if it's the same as yours. Delta used to offer a quick-release attachment (which I have on my saw) that eliminates the upper allen screw and replaces it with a tool-less clamping system. Big improvement, IMO---don't know if it's still available.

As for the poor cutting action: the first things that come to mind are: 1. dull blade 2. low tension.

1 1/2" stock is pretty thick for a scroll saw, so you will need a sharp blade with as few teeth per inch as possible. It's likely, now that I think about it, that the sawdust is not clearing the work well enough during the cut and generating heat, causing the blade to expand a bit, leading to the bowed cut you are experiencing. Try a coarse blade, good tension, and a slow feed rate, to allow the dust to clear. My .02

[Rob Miller]

Thanks for your thoughts. I'll look for the attachment. The old system is nonsense. I think I'm using a #12 blade. As for the tension, I'm not really sure how tight to make it. It popped out of the cinch once so I'm reluctant to go too tight. How do you know when the blade is properly tight?

The damned thing was vibrating like crazy -- bouncing all over the table until I clamped it down. Is that normal?

[Jerry Miner]

Yeah-- I think a #12 is going to have a hard time in that cut. Olson makes a blade specifically for thicker stock---a 7 tpi hook-tooth:

Olson thick (http://www.highlandwoodworking.com/olsonthickwoodscrollsawblades.aspx)

My saw bounces,too. I keep it clamped down to a dedicated table---otherwise anything else on the table will walk off!

Tension---trial and error is the only way I know to get this. In your case, though, I think heat from friction is your problem

[Rob Miller]

Is it possible to use a pin-type blade on this saw (I think it's an older 40-150 model)? The parts list at ereplacementparts.com (http://www.ereplacementparts.com/delta-40150-type-1534-scroll-saw-parts-c-3275_3505_14026.html) shows both style blades. It's possible that only applies to later saws but the parts listing doesn't make this clear.

[Jim Finn]

I agree that you need a LOT of tension in the blade, slow saw speed if you have a variable speed saw, and very slow feed rate. Let the blade do the cutting. You should not push the wood very much. Scroll saw cutting this thickness of wood is the slowest cut I do in my shop. A LOT slower than a band saw.

[Myk Rian]

1 1/2" thick? No wonder you're having problems. That's band saw material.
I think to get anywhere close to a good cut will require you to check the set of all the teeth on the blades, and make sure they are perfect.