Scrollsaw blades breaking

[Tim]

Hi all,

I've been trying to scroll some 1/4" Hackberry using a #3MS blade on my Delta Q3. The #3 blade seems to be the perfect size for what I'm cutting, but I'm having a heck of a time with blades breaking. The first blade popped after about 3 minutes, but the second lasted more than 30 minutes before I changed it myself. The 3rd, 4th, and 5th popped either as soon as I turned the saw on, or just as the blade started to cut - and no, they were not installed up-side-down.

I contact the person I bought the blades from, and he said that if the blades were breaking close to the top or bottom, and they were, then I probably had the clamps on too tight. So last night, I loosened the clamps, but as soon as I tensioned the blade, it slipped out of the clamps - obviously I loosened them too much. So after some trial and error, I found the spot where the clamps were tight enough to hold the blade, and the blade didn't pop out of the clamps as soon as I got tension on the blade.

However, I haven't had any better luck with the blades not breaking, and I broke 3 more without getting any more cutting done. I've also tried not tensioning the blade as much as I would using a larger blade. So, for the time being until I can figure out why my #3's are breaking, I had to jump to a #5 ( after loosening the clamps a little bit ) which will work for most of what I'm cutting. But I would really like to use the #3's.

Has anyone had this problem before, or can someone point me to some guidelines for tensioning the blade? I'm assuming that my problem is more with tension than it is with clamping pressure.

TIA, Tim

[Phil-In-Mich.]

Yes, Tim, many people who first start out with scroll sawing will have a lot of problems with blades breaking. That is one reason blades are so in-expensive in the first place.

Don't forget to clean off the ends of your blades with Mineral Sprits or a quick swipe with a small file to remove anti-rust oil and compounds.

Most obvious is the blade manufacturer. Good quality blades are important; it has to do with removal of sawdust (OK, very small wood chips) or not enough cutting teeth in contact with the wood (minimum of 3.) In either case, the quality and hardness of the teeth, the blade metal, and the teeth configuration (standard, skip tooth, etc.) makes a difference. Best name brands I know of are Pegus and Flying Dutchman (Google). Olsen in Third place. Bottom of barrel: Vermont American, BORG house brands; these dull too quickly. I presume your delta uses pin-less blades.

The second is how fast the wood is being pushed into the blade, and the cutting speed (strokes per second) of the blade. Object is to let the blade cut the wood, not how fast you feed the wood. Scroll saw is not a table saw. Your feeding of the wood should not cause the blade to bend backwards more than a minor fraction of an inch.

The most common cause is side-to-side pressure. This is where your feeding of the wood is not uniform left-to-right, you are pushing the wood very slightly sideways, making the blade flex to the side. If you stop pushing does the blade continue cutting? When you stop pushing, and remove the finger pressure, the blade should stop cutting, the blade should not move the wood, and the blade should not leave any burn marks.

Scroll sawing is a learned skill, very few jigs or fixtures to compensate for lack of time at the saw cutting wood. Get some scrap wood (or better yet some cut-offs from other projects) and cut some practice.

Best place for scroll saw newbies are one of the web based scroll saw forums. Google, or let others recommend a moderated forum for you.

Lots of scroll saw reading at Rick's place:

a really lot of reading. Wait for wintry no major sports event weekend. Like tomorrow.

Phil

[Phil-In-Mich.]

I forgot to mention two things:

There are two blade tensions, blade chuck clamping pressure, and blade tension. Your friend is correct about the blade clamping pressure, but only if the ends of the blades are clean.

The other, blade tension must be tight. Way too many newbies don't have enough blade tension.

Phil

[Tim]

=A0 a really lot of reading.

Hi Phil,

I've been scrolling for several years, so I'm not exactly a newbie. But this is the first time I've tried to use a blade that small. And I had never been told to clean off the ends of the blade before I get started - add that to the list.

The blades I'm using are Olsons, and yes, they are pinless. I have a small pack of Flying Dutchman, but I don't remember what size they are. Something else to check on tonight when I get home. Like I said, some of the blades broke as soon as I started a cut. I know better than to feed too fast, so I'll stop short of saying that it can't possibly be my problem. Side-to-side pressure should also have been pretty minimal since the cut line was pretty straight. I don't have the steadiest hands in the world, but I do fairly well. Using your test, yes the wood does stop moving, and the blade does stop cutting if I remove finger pressure. And in what I've cut on my current project so far, I haven't had any burn marks.

I appreciate the feedback, and I'll experiment a little bit over the weekend with cleaning the blade ends and different tensions - I thought I might be putting too much tension on the blade. Curious, though - why would #3's give me so much grief, but not #5's? 5's aren't THAT much bigger than 3's.

Thanks again, Tim

[Phil-In-Mich.]

Tim:

That is my BAD. I misread your post and got the impression you only just recently acquired your Q3.

This is a bit of trivia: Many older Delta machines way prior to Y2K were set up to accept 5.00 +/- inch blades. Many of the better quality blades are now a metric length (13cm?) which is about 5.1 plus inches long. Some people need to snip off a shade under 1/8 inch to get the blade and the blade tension back into the center of the blade tension range.

Also do this test: chuck up a blade and run the saw at 3/4 speed without cutting any wood. Saw should run for at least 10 minutes without breaking the blade. If blade breaks before 10 minutes, problem is with saw. You don't need to run the test for more than ten minutes, but your choice and your time.

No reason your saw should not handle blades down to #1, or #0 or even down to #2/0 (double aught). problems with a #3 don't make sense.

Phil

[CW]

By the pattern of breakage, it sure sounds like a bad batch of blades.

[Martin H. Eastburn]

I heard that Hackberry is fibrous and the strands grab chain saws and now it looks like scroll saws also.

Mart> Hi all,

[Tim]

Hi Phil,

I'll definitely run the test over the weekend, but kudos on the choice of blades! I had a couple of Flying Dutchman #3's, and had no problem. One blade cut for about 40 minutes, and I think it's still good for the rest of the project - about 15 minutes tomorrow. And compared to where I usually buy my Olson's, the Flying Dutchman's are a little less expensive. So I think I'll be changing my brand of blades.

Thanks again for the tips!

Tim

[Tim]

I didn't have any problem with the Hackberry when we cut it. The city was doing a road project, and my neighbor and I got part of the tree. We had it milled and air dried it, and it turns really nice. Never had any trouble with it grabbing or being stringy. Actually, it's been really nice to work with so far. I resawed thicker boards for this project, ran it through my planer, and I've had really nice, clean cuts on the scroll saw. I'm trying to figure out what else I can use it for.

[Martin H. Eastburn]

I related my friends woes and tales. I have cut it myself and didn't have chain saw problems. My tree was mostly dead.

Mart> >> I heard that Hackberry is fibrous and the strands grab