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How Much can a blade affect a miter cut.

3K views 20 replies 12 participants last post by  knotscott 
#1 · (Edited by Moderator)
I've been trying to cut some 45 degree miters for some boxes i'm making for a girlfriend, and i'm having a hell of a time getting a straight miter.

How much effect will a dull blade have on the miter cut. I'm using maple so the wood is pretty hard. and it seems like like i get a bow in the miter when looking at it from its edge. These miters are 4-6 long. I tried some cedar, and it seems like these came out much straighter, was this because the wood is softer.

Can anyone recommend a quality blade, how many teeth?
 
#2 ·
If the blade is dull, it should burn the maple while cutting, plus be hard to pull thru the maple. I am wondering if there is some slop in the saw carriage for you to be getting such a cut. Have you tested to be sure it's not an optical illusion ?

A dull blade will also cause chipout, especially at the ends of the cut.
 
#3 ·
clean and sharp
is what works best

and stops or clamps
to keep the wood from 'creeping'

i never use thin kerf blades
for just this reason

i know some like them
but to me they are just a marketing ploy
to use less steel
and jack the price
for 'new and improved'
 
#5 ·
I was just reading a forum topic on clean blades, and i can honestly i have never cleaned a blade in my life, guess i'll start tonight. I only woodwork as a hobby so my table saw and blades dont get that much use, just a couple of times of week so i think my blades are dirty and but still sharp.
 
#6 · (Edited by Moderator)
Another important effect is whether there is damage to the blade.

If, for instance one edge clipped a hidden nail or staple and got chipped at some time in the past.
This will make the blade try to cut at an angle, but the bearings and shaft are fighting to keep it straight.
The result is some interesting warpage in the blade in the cut; might even look like a wave pattern.
 
#7 ·
A blade that is designed for a miter saw is critical. I loaned my saw to a friend. When it came home it had a different blade on it. It was recently sharpened and all but it was not a saw blade for that kind of work and you could not make two 45 deg cuts come together and close up or enven make a 90 degree angle. A new blade took care of that.
 
#9 ·
If cleaning your current blade doesn't help, or if the current blade isnt' a high quality blade, I'd definitely look to a new one. Considering the task, I'd opt for a full kerf blade to reduce the chance of deflection (though I do think a high quality thin kerf blade for many TS operations are fine).

Without knowing your blade budget, I'll start with some bargains….the Delta 35-7657 40T ATB general purpose blade is still on sale through Cripe or Amazon for < $30 shipped. This German made Onsrud 50T blade is ~ $25 shipped. For ~ $70, the Infinity Combomax is the best of the 50T blades I've used. Nearly any high quality 40T to 60T 1/8" full kerf blade should do well if it's suitable for TS.
 
#10 ·
Budget. what's that?, when it comes to tools and hobbies for me if i want it and need it i pretty much get it. The mortgage company can wait. Haha…as far as blades, i've purchased 10 or 11 blades thinking they were all dull, i'm so excited to get home and clean my blades and hopefully they work again.

whoohoo
 
#14 · (Edited by Moderator)
A dirty blades acts like a dull blade, and actually causes premature dulling. Definitely keep them clean!

It's possible that your blade is actually deflecting during the cut. There are few things that can cause that. We know you're using a Jet contractor saw, but not what blade you've been using.
 
#16 ·
Is the blade adjusted high enough? If the blade is not high enough you will get a dished cut., ummm this might be the cause of some of my problems, as i was trying to keep the blade as low as possible in an effort to minimize any kind of deflection. Your term "dished" made sense to me and after thinking about the blade etc, this could be the case..thank you.
 
#19 ·
Is your Fence set at 45 with your blade at 90 or is your blade tipped to 45? The reason I ask is that your miter guage may have just a bit of "slop" in in and when you push it through the blade it may be causing the problem.
 
#20 ·
I had exactly that problem while tuning my new sliding miter saw. Didn't matter - cuts at 90 or 45 degrees all seemed to be bowed in the middle. It looked to me like the blade was actually flexing during the cut.

I finally replaced the cheapo blade that came with the saw and everything looks good. I have trouble understanding why the blade makes sooo much difference. I mean, I can see the quality of the cut varying, but I have trouble seeing why a cheap blade would flex more especially since they were both full size blades, not thin kerf. I can attest that it does make a difference.
 
#21 · (Edited by Moderator)
The performance of blades can vary a lot. All steel is not created equal, and is not treated equally once formed. The quality and consistency of the steel, the tensioning process, the design of the expansion slots, anti-vibration/anti-noise slots, balance, how it handles heat, and a bunch of other factors are all variables of blade performance that pertains to just the body. The carbide, sharpening, and tooth geometries are other huge factors. There's a lot more to the better blades than profit margin.
 
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