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Forum topic by woodbrain posted 11-18-2015 04:01 AM 1862 views 0 times favorited 67 replies Add to Favorites Watch
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woodbrain

21 posts in 597 days


11-18-2015 04:01 AM

I have a powermatic model 66 with a riving knife. I think the knife is made by jet. It has the kickback drop down things connected to it.

I’m ripping 1×12 cedar. After I cut into the cedar about ‘1.5-2’ I can no longer feed the wood into the blade. Something is binding up, and I’m not sure what to do, if there is anything that can be done?

Any ideas?

Thank you.

Allen


67 replies so far

View JAAune's profile

JAAune

1642 posts in 1779 days


#1 posted 11-18-2015 04:08 AM

When saw binds, shut off the machine (if you don’t have a knee switch, install a makeshift one), wait for the blade to stop, then lift the guard off and take pictures from all angles. If you can’t identify the hang-up, someone here may be able to spot it.

Could be warping wood binding on the anti-kickback mechanism or improper alignment of the splitter or pawls.

-- See my work at http://remmertstudios.com and http://altaredesign.com

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waho6o9

7172 posts in 2040 days


#2 posted 11-18-2015 04:08 AM

Maybe use a bandsaw and then rip to size on the table saw.

View bigblockyeti's profile

bigblockyeti

3668 posts in 1183 days


#3 posted 11-18-2015 04:12 AM

It almost certainly sounds like you have a slightly misaligned riving knife or you’re using a thin kerf blade with a full kerf riving knife. Has the fence been very, very closely aligned with the blade? That too could cause a problem.

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MrUnix

4221 posts in 1662 days


#4 posted 11-18-2015 04:18 AM

Sounds like you have a splitter, not a riving knife… splitters typically have the anti-kickback pawls (“drop down things”), not riving knives. Most likely you just need to align your splitter and verify that it isn’t too wide for the blade you are using. Pictures would help to verify.

Cheers,
Brad

PS: Did this just all of the sudden start happening or is it a new setup that you haven’t used before?

-- Brad in FL - To be old and wise, you must first be young and stupid

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woodbrain

21 posts in 597 days


#5 posted 11-18-2015 04:22 AM



It almost certainly sounds like you have a slightly misaligned riving knife or you re using a thin kerf blade with a full kerf riving knife. Has the fence been very, very closely aligned with the blade? That too could cause a problem.

- bigblockyeti

How would I know if I have a thin kerf bland and/or a full kerf riving knife. Intuitively, I think this might be the problem.

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woodbrain

21 posts in 597 days


#6 posted 11-18-2015 04:26 AM

I haven’t used the saw for a few years. I moved and it’s been sitting in the garage. I went through the saw and reajusted everything, cleaned, greesed the gears. Pretty good going through. You’re right it I think I have a splitter. Again, I’ll get pictures tomorrow. I’ve spent quite a bit of time aligning the splitter. would I be better off using a riving knife? If so, which one should I get for my model 66. Thank you guys.

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MrUnix

4221 posts in 1662 days


#7 posted 11-18-2015 04:33 AM

A splitter is a splitter… even when it’s called a riving knife :)
(they both perform the same function)

I don’t believe there is a way to retro-fit a riving knife on the pm66, but I’m sure someone will correct me if I’m mistaken.

To verify the splitter isn’t too wide, feed some stock into the blade about an inch or two, turn off the saw and then back out the wood. Then use the kerf made by that cut to verify it will slip past the splitter without binding. If it does, then it’s most likely just an alignment issue.

In addition to the above, you could also temporarily remove the splitter and see if things still bind… if the cut goes fine, then you know it’s the splitter causing the problems.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View MC's profile

MC

147 posts in 1810 days


#8 posted 11-18-2015 10:53 AM

I would advise against removing the splitter. If the issue is being caused by the wood warping after internal stresses are relieved you could get a serious kickback without it.

In addition to checking the splitter alignment check the alignment of your rip fence. A fence out of alignment towards the blade can also cause a bind…and kickback without a splitter.

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bigblockyeti

3668 posts in 1183 days


#9 posted 11-18-2015 11:26 AM

Full kerf blades all or almost all remove right at 1/8” so your splitter would need to be just under that dimension. Thin kerf blades typically remove closer to 0.090” necessitating a thinner splitter.

View SirIrb's profile

SirIrb

1239 posts in 693 days


#10 posted 11-18-2015 12:14 PM

Remove the knife and praise the day you did so. I have never used one that I can remember and all my stock rips just fine.

-- Don't blame me, I voted for no one.

View rwe2156's profile

rwe2156

2192 posts in 943 days


#11 posted 11-18-2015 12:43 PM

MrUnix is right that’s a splitter not a riving knife.

Sounds like either the wood has a lot of tension or you do not have a jointed edge against the fence.

I have a Jet and the splitter/blade guard that came with it is useless.
I installed it, immediately took it off and never put it back on.

There are alternatives like the MicroJig or a home made splitter.
They are not identical to a riving knife but basically perform the same task.

I’m with SirIrb^ take it off and see what happens – but best to have some kind of splitter like I mentioned above.
Make sure you are using push blocks (they are the best TS safety device there is).

If you’ve just got to have a blade guard you can always install an aftermarket one or make your own.

-- Everything is a prototype thats why its one of a kind!!

View HokieKen's profile

HokieKen

1750 posts in 601 days


#12 posted 11-18-2015 09:23 PM

Another thing to try is try ripping some other wood you know is stable. Plywood would be a good choice. If it runs through without issue, your cedar may not be dry or may have unusual internal stresses.

That’s just something to try. Smart money’s on the splitter being too wide or the fence being misaligned.

-- Kenny, SW VA, Go Hokies!!!

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Kazooman

626 posts in 1415 days


#13 posted 11-18-2015 10:37 PM

Wood is wood, and it moves. Sometimes there is a lot of stress built up in a piece that is only revealed when you try to rip it. If you have a splitter or riving knife and the wood bends in on the kerf and grabs, you have a good chance to shut the saw off and remove the stuck piece. Without a splitter or riving knife you may end up wearing the piece on your forehead.

Here is a picture (I hope it shows up in the correct orientation!) of a piece of hickory I was working a few months back. The wood is kiln dried hickory purchased from a very reputable dealer (Johnson Lumber in Charlotte, Michigan). The original piece had acclimated in my shop for at least two months. The original was 1 3/4” By about 10” by about 5’. I had milled out several pieces with no issues. I had this piece that was 1 1/8” X 4” X 22”. It had been jointed and planed and was smooth and square on all sides. I tried to rip about 1” off of one edge. About 12” into the cut it bogged down and actually tripped the circuit breaker on my 3Hp SawStop saw that, by chance, had the original SawStop 40 tooth carbide combination blade on it at the time. This blade works just fine on all manner of hard woods, cross cutting or ripping.

Over the course of the 12” cut, the wood moved enough to close the kerf to the point that it bound the blade and stopped the saw even with the splitter in place. As you can see, the cut off piece also actually lifted over 1/8”. None of the other pieces I milled out of this larger blank gave me any problems. The end grain on this piece doesn’t suggest to me that there should be any special concerns. The other pieces had comparable grain. Why this one piece acted so differently and had stored so much tension is a mystery.

As you can see, I tried to complete the cut from the other end, but the wood also started to bind and I quit. I will keep the piece as a reminder to be careful.

I will keep the splitter or riving knife in place whenever I can.

PS: I took the picture in the portrait orientation with the IPad I am using for this post. The forum software has rotated it 90 degrees. I have tried using the IPad in landscape orientation and the forum shows the pictures upside down. I have said previously that I think this is a “feature” of the interface of Apple products with the forum. You can still see the picture just fine.

View joey502's profile

joey502

487 posts in 981 days


#14 posted 11-18-2015 11:10 PM

I would guess the splitter is not the problem. The OP says his problems began 18-24” into the cut, if the splitter was in the way he would have discovered that about 16” ago.

My guess is the stress is closing your cut behind the blade or your board’s edge is not straight enough to reference agai.st the fence.

View Rick M's profile

Rick M

7913 posts in 1843 days


#15 posted 11-19-2015 03:53 AM

Allen, you are the guy with eyes on the situation, no one can answer your question better than you. And no one can do anything but throw out guesses with the scant information you’ve provided. Stop the saw and see where the wood is binding.

-- http://thewoodknack.blogspot.com/

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