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Context: I'm new to woodworking and starting it as a hobby. I bought several cheap tools (Deko) and I'm learning mostly through YouTube.

When cutting circular cuts (in 20mm chipboard) using a Deko cordless jigsaw and blades (T111C HCS) I got from AliExpress, I noticed the blade gets hot to the touch after around a minute of cutting (non-stop). I've also seen what I think might be smoke (although it may also be fine dust).

Right now I cut for around 1 minute and pause for a few to let the blade cool down. Is this necessary? Is this normal?

NirIzr
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    Further to my point about being careful about learning from YT, do try to rely more on well-regarded books to pick up the best working practices and methods as you're teaching yourself the craft. It's very hard to un-learn bad habits. Are there many (any?) woodworking authors in your native language? Your English seems more than good enough to be able to get all you need to from most English-language books, but if there is anything decent in your own tongue you might as well take advantage of it. – Graphus Oct 14 '21 at 16:03
  • Aside - 20mm is quite thick for a jigsaw, and your cuts will lack vertical straightness as the blade dances about. Your next tool purchase might be a job saw (circular saw, Skilsaw) or a used table saw. – Criggie Oct 14 '21 at 18:40
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    Good point, @Criggie, however, chipboard tends to be pretty uniform in construction, so there isn't grain to cause the blade to wander, so the effect will be noticeably less than in real wood. – FreeMan Oct 14 '21 at 18:59
  • A jigsaw blade will get hot, but it should not smoke after a minute. This indicates a poor quality blade that dulls very quickly - or the wrong tooth pattern. Are you trying to cut wood with a blade meant for Metal?. Wood blades are typically 6 TPI (Tooth Per Inch). You can get a Diablo Carbide blade for less than ten bucks and it will last for quite a while. – Gmck Oct 14 '21 at 19:50
  • @nirlzr is your wood wet or damp at all? It could be steam – Criggie Oct 14 '21 at 21:57
  • Thank y'all for commenting! I'll reply within a day or two but i wanted to say i appreciate your answers and suggestions! – NirIzr Oct 15 '21 at 19:53
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    @Graphus I'm used to learning online and that's mostly in English. I prefer the higher quality of English material verses the accessibility of Hebrew. You got me thinking, so I also asked a question about learning material! – NirIzr Oct 16 '21 at 19:51
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    @Criggie - The blade does not wander but it does lean into the curve. I understand this happens (especially because of the material I'm cutting) but cat be avoided. I can't get over it, however, even when using a brand new (although cheap) blade. – NirIzr Oct 16 '21 at 20:03
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    @Gmck It does not smoke after a minute, but I've starting pausing frequently to avoid it smoking after a few minutes. The blade is a random T111C I got from AliExpress. I've also got a few T144D and T244D. I think they're all wood blades. The wood isn't wet or damp as far as I can tell. – NirIzr Oct 16 '21 at 20:10
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    @NirIzr Wood blades typically have larger teeth and less of them per inch of blade length. When cutting dense material like MDF or chipboard, I use a blade with less teeth (6 to 10). These will cut better and faster with less heat. Also let the tool do the work. It's tempting to push the saw to cut faster, but that can result in heat buildup and burn marks. My go to blade is a Diablo: https://www.homedepot.com/p/DIABLO-4-in-x-6-TPI-Fast-and-Wood-Bi-Metal-Jigsaw-Blade-5-Pack-DJT101DF5/313114938 Good luck with your project! – Gmck Oct 16 '21 at 22:14
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    I've used metal-cutting jigsaw blades successfully on wood, and I'd recommend them for melamine-coated chipboard to reduce chipping on both surfaces. But you have to go gently, and back off the cut frequently to clear the teeth - clogging could be causing heat with wood(dust)-on-wood friction. This is true even with some wood-cutting blades. You should be able to tell if it's smoke from the smell and possibly darkening of later stages of the cut edges. Scorched chipboard smells rather like wood smoke but worse – Chris H Oct 19 '21 at 09:39

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I don't pause specifically to cool the blade when I'm cutting with any tool. I do, however, usually burn my fingers slightly if I have to change the blade because I always forget just how hot the things get. I usually have one glove handy if I need to change blades during cutting.

I find that there are often pauses in my working as I readjust myself to cut at a more comfortable angle. Particularly when cutting curves, you're going to have to stop to rearrange yourself & the work simply because your shoulder doesn't rotate to allow you to make a full circle in one non-stop motion. I usually don't even take the jig saw off the work piece for those type of adjustments unless there's a possibility of knocking the saw off the work or I'm cutting in a slot in the work support and don't want to catch the blade there.

Higher quality blades will, in addition to lasting longer, starting and staying sharper, and being made more accurately, will likely also take the heat a bit better, but I'd bet you'd be hard pressed to find any accurate data on how much impact heat has on the blade life.

Chipboard/particle board/MDF is going to be hard on blades no matter what tool or what quality you purchase. These materials, because they have so much resinous glue in them are simply harder on the blades than "real" wood is going to be.

You mention that you think you've seen a bit of smoke. That's possible because of the glue in what you're cutting. The clue is to look at the cut edge to see if there are scorch marks. If there are, then there was a bit of burning during the cut. If they are a problem for the finished piece, a little bit of sanding will get rid of them.

FreeMan
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  • The blade could be getting hotter than normal because you are using the wrong tooth count for cutting chipboard. What is the tooth count of the blade you are using? – Programmer66 Oct 14 '21 at 16:08
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    Good point, @Programmer66, but that should probably be a comment on the Question, not my answer... – FreeMan Oct 14 '21 at 18:59
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Should I let the jigsaw blade rest once it heats?

Not usually, no. It's perfectly normal for jigsaw blades to get hot in use.

Even hand saws can get uncomfortably hot1 if you're sawing enough and any traditional saw is made of plain carbon steel. Modern jigsaw blades should be made of much more heat-tolerant alloys that don't care even a little about running hot, up to about the temperature that you scorch wood.

If you are getting smoke2 it probably indicates you're running too hot, in which case you can take a break or cool the blade down by swabbing it with a damp cloth or dipping it in water. This won't harm the blade, any more than dipping chisels in water periodically during grinding does — despite tales to the contrary3 — and again most chisels are not a modern alloy.

One thing to note in relation to jigsaws specifically is the relatively thin blades being held at one end only mean they work best if they're run at their 'natural pace', and that pace is, um, not fast4. Try to let the saw do the work; remember that it's not a race. It's hard to describe how this feels in words, much easier to demonstrate in person (as it was to me), but you should experience little resistance to forward motion of the saw. Imagine controlling the saw with one hand and pushing it forward with just one fingertip of the other hand and that might give a good impression of how much forward pressure you should use.

I'm learning mostly through YouTube

You didn't ask about this but I wanted to address it in the context of power-tool use. Be very careful who you learn from! There are more than a few high-profile YouTube woodworkers and makers who have awful shop-safety practices.

Try to learn to identify who they are and not pick up their bad habits!

1 Drill bits being driven by a hand drill can too, and much hotter, and it is rare or unheard of for modern bits to be cooled except to make them comfortable enough to change if the user can't or won't wait for them to air-cool.

2 Use your nose, not your eyes, to determine this as there's no mistaking the odour.

3 Although there are seemingly logical explanations about how it can occur it has never been demonstrated to harm the steel in normal grinding operations, and, dipping in water has been standard workshop practice since before any of us were born.... if it did cause a problem someone would have noticed and we'd all know about it by now :-)

4 Except in thinner material and soft woods. With thicker and tougher material (and 20mm chipboard definitely qualifies) the cutting rate should actually be quite slow.

Graphus
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    Thanks! I do think I'm gentle with pushing the saw forward and put most of my effort into pushing it down on the material. I can probably do a better job, though. I do appreciate your comment about safety, and I'm aware not all youtubers practice shop-safety and I'm being careful when using a power saw. Less so wrt sawdust and noise, tbh. – NirIzr Oct 16 '21 at 18:57