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2 tablesaw questions - burning and mini-kickback

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Forum topic by unclearthur posted 04-07-2019 03:33 AM 560 views 0 times favorited 13 replies Add to Favorites Watch
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unclearthur

255 posts in 2151 days


04-07-2019 03:33 AM

I was cutting some tapers in about 2” hard maple, using a sled on the tablesaw, setup like this:

Burning
I kept getting a lot of buring at the start of the taper, where the blade first touches the wood:

Once the blade was fully in the wood it was fine.

This persisted even when I tried to do the start of the cut faster. Brand new (ie sharp), full kerf blade .....

Easy enough to clean up with a hand plane, but I was wondering why does it burn at the start of the cut and not after? Happened 8 times in a row. Suggestions to avoid?

Kickback
I almost always use a magnetic featherboard on the left side of workpieces when ripping on the tablesaw.

Today, I did similar in the setup above, with the blue featherboard an inch or so behind the blade and pressing the sled against the fence. After completing a cut and pushing the sled beyond the blade, while the blade was spinning down, the offcut (a taper / wedge) somehow got caught between the featherboard and the blade and BAM it burst into two and got thrown across the shop.

I was wondering if others had experienced that sort of issue with offcuts sort of chattering their way back into a feather board and then getting jammed up ?

Thanks for any replies.


13 replies so far

View therealSteveN's profile

therealSteveN

2629 posts in 938 days


#1 posted 04-07-2019 04:54 AM

Maple, especially soft Maple, and Cherry are notorious burners, and even if everything is ok, you can get it, like you said sanding or a hand plane and you are good. If you slow your feed rate much, you will note it more. Possibly you are hesitant at first, then once you get moving push a bit faster stopping the burn. I hate to ever say rush when feeding into a TS, but once you make your move try to be stable on the amount of forward you use. If it isn’t burning all the way through, you are adjusting your feed.

The only other thing I would want to check, is measure your wood accurately to make sure you are 4 square. If the stock has a “fat” face that may be it, but if the stock is good, and you are consistently getting the burn at the start then I’m thinking it’s a hesitant start.

For the kickback move that fingerboard back off the blade a bit and you shouldn’t have further problems

-- Think safe, be safe

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Tony_S

967 posts in 3446 days


#2 posted 04-07-2019 10:15 AM

The burning is the result of the tapered shape you’re cutting. As the blade starts cutting, you only have material on one side of the blade on initial contact, so it’s deflecting the blade to the left. The result is the right side of the teeth rubbing on the material. The problem goes away after the blade has corrected itself. Looks like a combination blade. Not the greatest for ripping, especially in this situation. Use a good quality, heavy rip blade and the problem should go away, or at the very least, improve greatly.

Kick back….your feather board created a pinch point. Get rid of it. You’re sled looks oversized and cumbersome to say the least. If you’re concerned about the sled drifting from the fence, put a runner on the underside of your sled and use the miter slot instead and get rid of the fence as well.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

View BlueRidgeDog's profile

BlueRidgeDog

485 posts in 143 days


#3 posted 04-07-2019 11:03 AM

As Tony states, the blade is deflecting. It could be one of those thin blades or dull, but for my table saw work I always use a standard blade for rigidity. A sharp and stiff blade is a safe blade, in my opinion.

Unrelated, but I cut my tapers on the bandsaw and just clean the line with a plane. Fast, safe, simple.

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bondogaposis

5371 posts in 2715 days


#4 posted 04-07-2019 12:46 PM

I think the problem with your sled set up is that for the size of material you are cutting the sled is too large and cumbersome. Make a smaller one and put a runner that rides in the miter slot and then you won’t need the feather board or the rip fence.

-- Bondo Gaposis

View unclearthur's profile

unclearthur

255 posts in 2151 days


#5 posted 04-07-2019 07:35 PM



..... it could be one of those thin blades or dull, but for my table saw work I always use a standard blade for rigidity. A sharp and stiff blade is a safe blade, in my opinion.

Actually its basically a brand new good quality blade, full kerf so I don’t think the problem lies there. But it is pretty thick (2”) hard maple so maybe there is a bit of deflection as said above until the blade gets buried.

On the featherboard / kickback, I can easily use the sled without the featherboard, so no problem there, but as I regularly use a magnetic feather board on the left side of boards during rips (placed before the blade of course), I was wondering if others had had problems with off cuts wandering back and getting jammed?

View CWWoodworking's profile (online now)

CWWoodworking

438 posts in 542 days


#6 posted 04-07-2019 07:46 PM

I was wondering if others had had problems with off cuts wandering back and getting jammed?

- unclearthur

I have same problem with a small taper leg I make. The only thing I came up with is putting a long screw in the off fall so I can pull it away.

I don’t like doing it, but don’t know what else to do.

View knotscott's profile

knotscott

8279 posts in 3739 days


#7 posted 04-07-2019 10:19 PM

Maple burns more easily than most, and that cut looks pretty thick. Using a blade with fewer teeth, and raising the blade a bit might (if you can) help.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Craftsman on the lake's profile

Craftsman on the lake

2959 posts in 3801 days


#8 posted 04-07-2019 10:47 PM

It just burns sometimes. Especially with harder woods. I often cut them a hair wider then run pieces through the planer when possible. Might be difficult with a taper.

I have also noticed that a steady feed with no slowing down or stopping helps.

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

View mike02719's profile

mike02719

101 posts in 4149 days


#9 posted 04-08-2019 12:33 AM

Is that a saw blade painted red? I refuse to use painted blades because of burning and other overheating issues. Just saying! May or may not be the problem.

-- Mike, Massachusetts

View sawdustdad's profile

sawdustdad

379 posts in 1249 days


#10 posted 04-08-2019 01:07 AM

You should be using a dedicated rip blade for that application. The ATB of a crosscut or combination blades’s teeth create bending stresses in the blade when cutting on one side of the blade. The flat top bevel of the rip blade is not subject to these same forces. Change the blade.

Lose the feather board. There is absolutely no reason to use a feather board when the stock is clamped in the taper jig. And there is never a reason to use a feather board when ripping like that anyway. The feather board is used to hold the stock against the fence for rabbeting, dados, etc. NOT for RIPPING.

Your jig is NOT too big, and the comments that imply that is a cause for the problems are incorrect. The jig is fine.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

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unclearthur

255 posts in 2151 days


#11 posted 04-08-2019 06:34 AM


You should be using a dedicated rip blade for that application. The ATB of a crosscut or combination blades s teeth create bending stresses in the blade when cutting on one side of the blade. The flat top bevel of the rip blade is not subject to these same forces. Change the blade.
- sawdustdad

Got it. Rip blade next time.


The feather board is used to hold the stock against the fence for rabbeting, dados, etc. NOT for RIPPING.
- sawdustdad

Not sure I follow. Why not?

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sawdustdad

379 posts in 1249 days


#12 posted 04-08-2019 07:02 PM

You are using the feather board in the wrong application. You are pressing the cut off back into the blade. No wonder it kicked back. The cut off should not be touched by anything. Except, perhaps a splitter behind the blade.

Looking again at your first post, you say you used the feather board to push the jig against the fence. If it’s the jig alone, that’s OK. But if the feather board pushed against the board you are cutting, then that’s not a good idea. Keep the feather board under the tapered piece, pressing on the edge of the taper jig itself, and not on the wood you are cutting, and you’re good. Just be sure the feather board is thin enough so that it in no way touches the board you are cutting or you’ll interfere with the cut.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

View sawdustdad's profile

sawdustdad

379 posts in 1249 days


#13 posted 04-08-2019 08:25 PM

Here’s what you should use if you need help keeping stock against the fence when ripping. Notice that the rollers are between the fence and the blade, pushing on the stock against the fence and do not touch the cut off piece.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

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