hi,
I just purchased a brand new plywood blade(it has many teeth on it) for my circular saw. I noticed that cutting either 1/2″ or 3/4″ plywood with the good face down that the plywood edge would get burned. I put the blade in another saw with the same results. I switched blades to a 40 tooth blade and the cut was perfect but just a little rough! What is the problem here? I probably should buy a blade somewhere between the 40 tooth and the many tooth plywood blade just for cutting plywood. What advice does everyone have for this problem?
thanks,
Dimitri
Replies
Put the good face up as you cut.
>>Put the good face up as you cutAre you serious? That runs contrary to all I have ever read or done in over 40 years of cutting plywood with a circular saw.Howie.........
Sorry, I read "circular saw" as "variety saw" or commonly known as tablesaw.But after rereading, I see he's talking about a skilsaw. So yeah, good face down.
Plywood blades have small gullets and poor thus poor chip clearing, making it easier to burn the ply as you cut. Also they traditionally are made of high speed steel, not carbide, which reduces hardness and cutting life between sharpenings.
I use a combination blade, carbide, with 40 teeth or more. The more teeth the smoother the cut. But if want error free cutting, score the veneer before each and every cut. A pain for sure, that's how plywood is.
Are you using a guide to cut the plywood, or are you trying to do it freehand? It's virtually impossible to avoid some amount of wiggle when trying to freehand a cut and that's probably causing some of your problem.
I use a 60 tooth carbide finish blade in my circular saw and make my cuts using a guide. I also rig a temporary table on sawhorses so the plywood is totally supported while I'm cutting.
If the blade is an all steel one with a couple of hundred teeth, it will have very little set so the slightest misalignment if you are cutting along a straightedge, or freehand sawing will cause the blade to bind and burn the edge of the ply. The all steel blades really only work well in a table saw.
You would do better with a carbide blade meant for especially for plywood, guiding it along a straightedge. To work properly the edge of the saw's sole running along the straightedge must be exactly parallel to the blade or you will still have binding and burning problems. Most skilsaws need some adjustment to get the blade aligned properly with the edge.
John W.
Best for chip free (besides well tuned saw with parallel blade to fence and 90 d to travel of miter gauge) and throat plates and stabilizers) plywood is carbide tipped high alternate top bevel (HiATB) from Tenryu, Freud and Forrest.
Handle with love as teeth are dead sharp and pointy but the shearing action is unmatched . Trust me I have everything on the market as tool consultant and developer.
Why does one blade burn and not another? Its never easy to answer this question and actually give the right answer. The facts are that the more teeth that there are on the blade, the less room there is between them. This equates to more metal in contact with the wood at any given time during the cut. The solution is too push the saw faster so the metal is in contact with the wood in and particular area for a shorter period of time. Right.... problem is that with so many teeth the blade is far less agressive and pushing it harder only makes it hotter.
Dumping the plywood blade and going with a 50th carbide cross cut leaves you with a ragged edge and thats not what you want either. So what is the simplest solution... Scoring...but that's an extra step that you don't always have time for so sometimes you do it and sometimes you just plain forget to.
The only permanent solution that I know of is a variable speed circular saw, also known as a panel saw, (not all are variable but the best ones are). If you're interested let me know and I'll tell you more about VS circular saws.
Sincerely;
The Tool Guy
Been there and had the same problem with all the so called plywood blades. The blade I use now came as a surprize high performer. Due the the fine dust from cutting plywood I wanted better dust collection for the hand held 7 1/4" . Picked up the Makita for cutting hardi-planks. The blade included with it is #A-90451 28 teeth. As it was already installed I tried it free hand on some birch plywood, almost no splintering and its ready for edge banding without any extra cleaning up! Not a cheap blade ($45ish) But I keep three on hand. I have tuned my saw by making sure the base is parrallel to the blade this ensures there is no deflection from the stright edge.
My understanding is that more teeth gives a smoother cut, but more teeth also don't clear sawdust as well as fewer (larger) teeth. Accumulated sawdust creats more heat, which burns wood and dulls blades. I agree with using a straightedge, but I would also cut more slowly to allow the sawdust to not build up as much.
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