Need some blade help

I just recently started working with some 6/4 hard maple and am having some issues with burning on rip cuts. The burn marks are not along the whole edge, but just some areas. I checked the blade alignment and it seems ok. Also, I have the fence toed out slightly in the back. I also have the riving knife pretty much perfect with the blade. I'm using a Diablo 50 tooth combination blade. It leaves a really nice surface, except for the burn marks. I tried cleaning it, but that didn't seem to help. I tested out the stock 40 tooth general purpose blade that came with my saw to compare. The stock blade is not that great and I can tell by feeling the teeth that it's not that sharp. I ran a test piece through twice with zero burning. The surface quality was really poor with blade marks, and it also sounded like it was cutting poorly, but no burning.

It seems like it must be an issue with the blade. I was originally going to just get a ripping blade, but after testing the stock blade, am wondering if a better 40 tooth would be good enough. I'd rather not have to have dedicated blades and switch back and forth unless I really need to. Can 40 vs 50 tooth make that big of a difference with burning or is there something else going on with my blade? It hasn't been an issue on any other wood I've tested, but the saw is new and other than a bunch of test cuts, I haven't used it that much yet.

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Originally Posted by Christopher Cox

...It seems like it must be an issue with the blade...

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The issue is with the wood. Make rough cuts. Then make light finish cuts to remove the burning.

Hi Christopher, it's a combination of the wood and using the wrong blade.

Maple and cherry burn easily, and thicker wood needs a real rip blade, 24 tooth would be good for a 10 inch blade.

I normally purchase FS Tools blades, very good quality.

Regards, Rod.

A 50 tooth blade sounds really fine for rip cuts in 6/4 maple....

I think you would get better results with a more conventional rip blade and then cleaning up the saw marks on your jointer/planer...

It's difficult to totally eliminate burning on certain wood species, but using a more aggressive ripping blade and moving the material steadily and as quickly as you can safely through the cut will help. Any pause during the cut will burn from friction.

Quote:

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Originally Posted by Rod Sheridan

Hi Christopher, it's a combination of the wood and using the wrong blade.

Maple and cherry burn easily, and thicker wood needs a real rip blade, 24 tooth would be good for a 10 inch blade.

I normally purchase FS Tools blades, very good quality.


Regards, Rod.

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^This. I would also say that the longer time the blade is contacting the wood the better chance of burning; i.e., push thru as reasonably quickly as possible. This requires a true rip blade. Alternatively you might take a light trim cut after ripping with what you have.

Just as Jim says, especially in 6/4 maple. You really need a rip blade, 24 tooth and you may still need to run a light pass over joiner to clean it up.

Thanks guys. That's what I was thinking. What was confusing was that the stock 40T blade did not have any burning. I even paused mid cut to adjust my push stick without causing any burning. What I'm wondering is if it was cutting so roughly, that it wasn't generating enough friction. It left a really poor edge. The 50T blade leaves a super smooth glue ready edge, but that might be causing too much friction as a result of all the smoothing it's doing. I was worried that buying a higher quality 40T blade wouldn't make enough difference and I'd then still have to buy a ripping blade anyway.

I get absolutely zero burning or other marks now. This is after doing an extremely focused and methodical adjustment of my Unisaw. No surface is off by more than 1/128th, and really more like 1/256th. It took a couple hours, but hell, that's what beer and cigars are for in the shop. It takes multiple passes on each surface to get them all in optimal alignment, then the results are simply stunning. Last night I was cutting some thick MDF and thinking about this, because it runs nearly silently when everything is aligned. If you closed your eyes you might not hear the difference between the free-running saw and the sheet going through it.

Also for 8/8 hard maple I always use a Freud glue line rip cut blade.

As others have said, 50 teeth are too many for ripping 6/4 maple. I would recommend a Freud 30 tooth glue line rip blade. I've ripped cherry and maple with no problems on my 1-1/2 Hp saw with that blade and get near jointer quality cut surfaces. Be sure to raise your blade well above the top of the wood surface to minimize tooth contact with the wood.

I can change a blade on my saw in less than a minute, so why not use a dedicated blade for better cut quality.

A few observations:

1. Maple burns easily, so you may not get away with things you could with woods that don't burn as easily such as oak.

2. A 50 tooth combination blade isn't the best choice for ripping 6/4 of a wood that burns easily. It has too fine of a tooth pitch but most importantly too small of gullets. A 40 tooth blade has fewer teeth and larger gullets so that is why your test piece did not burn. I don't rip anything except plywood with a 10" blade with less than 40 teeth. I normally use a 30 tooth blade on my tablesaw as I rarely rip anything thicker than 8/4 on the tablesaw (bandsaw gets used for thicker stuff) and I got a cheap ($30) 30T blade from a local supplier at a big discount and it was a much better blade than I anticipated, so it pretty much lives on the saw.

3. A sharp low tooth count blade will cut much more smoothly than a dull higher tooth count blade. My cheap 30T blade cuts very smoothly while the original 40T blade that is now dull cuts notably less smoothly.

4. A rip fence that is out of alignment, a cup/bow in the board, or anything else that will push the board laterally into the blade will cause burning. Getting everything dialed in perfectly will reduce burning.

5. An underpowered saw will burn workpieces if it bogs down or stalls. If your saw has 3 hp or more for a 10" saw, you have more than enough power. 1 hp on a 10" saw is insufficient, I've used one and it can bog down on ripping "two-by" pine even with a good blade.

6. If you still get burning, rip a fuzz oversize and then run your board over the jointer to remove the burn marks and get it to the final size. I've never seen a jointer burn an edge-jointed board as the cutting edge contacts the entire edge board rather than the side of the blade.

I just wanted to give an update. I did a bunch of troubleshooting and test cutting on scrap. I think the issue was that my riving knife was slightly out of alignment. The back side opposite from the fence was just in line with the blade so that if you hold a straight edge up to the blade, the riving knife would touch, even though the front of the riving knife seemed to be within the kerf. It was at a very slight angle. I kept feeling a strange rubbing or vibrating towards the end of my cuts and knew something was wrong. I think the riving knife was rubbing a little on the off cut side and was pulling the wood slightly into the blade at times, especially since the fence was toed out, which would be the opposite direction. I ended up realigning the riving knife and toeing the fence back in a little. It's still toed out a hair, but less than before. One of the problems with a thin kerf blade is that you don't have much room for error in order to clear the riving knife. It basically has to be perfect to avoid any issues.

I also ended up getting a Tenryu gm-25540, which I'm liking a lot. I milled some of the maple last night and did some ripping with no burn or blade marks. I'm using a 2 HP hybrid saw, but with this blade it went right through easily. I'm not going to bother with a ripping blade at the moment. It would make more sense if I was using even thicker material or doing a lot of ripping, which I'm not at the moment.

Quote:

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Originally Posted by Christopher Cox

I just recently started working with some 6/4 hard maple and am having some issues with burning on rip cuts. The burn marks are not along the whole edge, but just some areas. I checked the blade alignment and it seems ok. Also, I have the fence toed out slightly in the back. I also have the riving knife pretty much perfect with the blade. I'm using a Diablo 50 tooth combination blade. It leaves a really nice surface, except for the burn marks. I tried cleaning it, but that didn't seem to help. I tested out the stock 40 tooth general purpose blade that came with my saw to compare. The stock blade is not that great and I can tell by feeling the teeth that it's not that sharp. I ran a test piece through twice with zero burning. The surface quality was really poor with blade marks, and it also sounded like it was cutting poorly, but no burning.

It seems like it must be an issue with the blade. I was originally going to just get a ripping blade, but after testing the stock blade, am wondering if a better 40 tooth would be good enough. I'd rather not have to have dedicated blades and switch back and forth unless I really need to. Can 40 vs 50 tooth make that big of a difference with burning or is there something else going on with my blade? It hasn't been an issue on any other wood I've tested, but the saw is new and other than a bunch of test cuts, I haven't used it that much yet.

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When I read you are using Diablo blade, immediately I associated it to thin blade... sometimes thinner than the riving knife or too close, in the latter case demanding very critical alignment.

Make a test, take off the riving knife and run some wood. Check the results.

All the best,

For the money most of us sink into our saws and wood, buy a decent 24T 3/32" thin kerf rip blade (< $60). It's the right blade for ripping 6/4" maple, and it won't strain your motor as much as a 40T or 50T for ripping thicker stuff. You'll have the blade (and likely the saw) for a long time.

Several things affect burning here are just a few I can think of:

1) Dull blade
2) Wrong blade
3) Underpowered saw
4) Inconsistent feed rate
5) Saw out of alignment
6) The wood itself

The first thing I would do is use a ripping blade. I am definitely not a fan of combo blades because they excel at neither xcuts or rips unless brand new.

I recommend the Freud LM74M010 (the chrome not the red). Awesome blade for the money IMO.

The second thing I would do is double check your blade-to-fence alignment.

If the blade is correct & sharp and the saw is aligned, then pay careful attention to the feed rate.

All that being said, on hard maple I always expect to leave room for clean up with a hand plane.