Tablesaw Issue

[Jack Frederick 135]

I have a Grizzly G0771Z. I love the saw but this is the second time I have had an issue ripping hardwood, so I have figured I would ask what I am doing wrong.

Both times it was 4/4 - 5/4 hardwood. Happened once with oak and once with walnut.

While ripping the wood, the wood pinches SO tight around the riving knife that I cannot push the wood any further. One time I had to shut the saw off and pry the riving knife out of the cut. This does not happen all the time while ripping hardwood, just some times. I ripped a piece of walnut tonight and it got VERY tight on the riving knife. Once I finally worked the piece through the blade, right before the cut was complete, the two pieces split very aggressively, like they where under pressure. Kinda freaked me out. My last cut with walnut I got smart (i think?) and once the board got tight on the riving knife I shut the saw off and wedged a flat head screw driver in the cut to separate the two pieces significantly more. Once I did that, the board went through the rest of the cut like butter! Is this safe? It felt safe, but it felt unnecessary... is there a better way? What am I missing.

I am running a general purpose diablo blade.

[Mark Hennebury]

Your wood is not properly seasoned and is under stress.

[Jack Frederick 135]

What’s the fix? The moisture content is 8%. How better to season it? How do I relieve the stress? Whiskey? Beer? Lol.

[David Eisenhauer]

The wood is what it is at this point. You can make a less-than-a-through-ripping cut on the wood (sometimes from each side if it is thick) and finish it up with a handsaw if you want to. Inserting wedges for either a power or hand cut works to help out as you have noticed. I have a bandsaw and tend to go to it when I encounter this condition, but it can happen there as well. I like my handsaw for final ripping when I encounter this. Slower, but not so hard on the equipment and way less exciting.

[Rick Potter]

Agreed. I am finishing my kitchen, and cannot help noting that the lumber I buy today from the same dealer has more stress in it than when I last built a whole kitchen over 20 years ago.

Assuming the fence is not set wrong, today's wood is more likely to either pinch at the riving knife or spit part way through the cut.

No expert here, but what I do is cut my wood a bit long, then rip my pieces about 1/8 to 1/4" wide. Then I let them sit a couple days in the shop before planing, or sanding all to finish thickness. This helps with making good joints. Then joint one side, and cut the pieces to size. It has made a big difference for the cabinets I am building for my house.

Hope this helps.

EDIT: A couple thoughts.

1. Are you running a thin kerf blade with a full kerf riving knife?

2. With wood that thick you should be using a real rip blade.

EDIT 2: I use a wedge also, as others have said. I have an assortment of plastic shims from Ace Hardware, and keep a couple handy on the top of my fence. I shut off the saw, and tap one in with my push stick, then finish.

[Andrew Hughes]

I do most of my ripping down on my bandsaw for this reason. Sometimes I can see the kerf opening and closing.If the wood is thick and unruly it will split the last three inches.
My tablesaw is for sneaking up to my final cut.
I also know no one really cares.:)

[Bill Space]

It happens sometimes.

I ripped a lot of wood (for me) recently, all ash from the same tree, and all kiln dried at the same time and stored together. I had one or two boards do exactly as you experienced. Had to turn off the saw and wedge something in the end of the cut to separate the pieces. Then proceed to finish the cut.

This is happened twice in several hundred rip cuts ( probably, did not count, but a lot).

Luck of the draw in my opinion.

Bill

[robert wiggins]

I do as you when that happens, shut the saw off as quick as possible for safety and by that time I have already determined that piece is under so much stress so I don't need it in a project so into the wood stove it goes.

[glenn bradley]

What’s the fix? The moisture content is 8%. How better to season it? How do I relieve the stress? Whiskey? Beer? Lol.

Beer for the wood and whiskey for you :). As mentioned, the material has the characteristics brought on by the handling from tree to retail and it pretty much is what it is. This sort of material is sometimes called "lively" and pops up now and again even in properly prepared and handled material. Since you have only seen it a couple of times it may well be within what folks would call "normal". The riving knife should help with this but, I too have had the grip of lively material be so tenacious that I had to stop the saw. Keeping the riving knife clean and waxed can help.

I have seen this tip and done it once or twice but, the pucker factor is greater than I prefer to subject myself to. If you notice the wood start to grip the riving knife, jam a wedge (that you just happen to have handy, right) into the kerf to hold it open in order to complete the cut. Although this works, there are many things wrong with it. You need to know when it is going to happen so that you have a few wedges within safe reach. You then have to throw caution to the wind and reach over the blade to insert the wedge behind the riving knife. I'm OK with that whole operation as long as I stop the saw first ;-)

[David Kreuzberg]

Jack,

I agree with everyone else, but I would advise against wedging a metal screwdriver in the saw kerf. If that screwdriver were to work loose and come in contact with that blade....

[Ben Zara]

Several people have asked this but I'll repeat it: What is the thickness of the riving knife compared to the blade?

[Jack Frederick 135]

David - good point in the metal screwdriver. Now that I know this is an acceptable fix, I’ll build a purpose built wedge that is safer for use.

To all - I will double check, but I am 99% sure the riving knife is sized correctly.

[Orlando Gonzalez]

Have you checked that your fence is aligned to the miter slot. The front and back of the fence need to be the same distance from the miter slot. If the back is angled inwards then you will be pinching the material against the riving knife. Some adjust the back of the fence outward by 1/64" to make sure it doesn't pinch. I have the G0833P and have had to realign it a couple of times but not by much. The instructions how to do it are in the manual. By front I mean the part of the fence closest to the operator and back is the one furthest away. You will be aligning the face of the fence to the miter slot. There are many ways of doing this and Youtube is a good source. I use a 12" ruler and pick either the right side of the miter slot (nearest to the fence) or the left side of the slot to take my measurement. I then adjust the fence, if needed, as shown in the instructions.

[robert wiggins]

For those that are inclined to use a wedge, ACE Hardware has 6 pks of plastic wedges. May be in the plumbing section.

[Marshall Harrison]

Most likely it is the wood as others pointed out. But my first thought was is the riving knife the proper size and aligned correctly.

[Jeff Bartley]

Jack,
Problem with lumber like this is that even after it's processed it will likely still move. Depending on its use this can be no big deal or catastrophic in a finished piece.
If you decide you can continue to use this lumber I would use a bandsaw to process it from rough. Reaching past the blade on a tablesaw, riving knife or not, seems like a bad idea!

[Al Launier]

Unless I missed this above I'm curious what the tooth count is on the blade you've been using...24?

[Jack Frederick 135]

I have been running Diablo 10 in. x 40-Tooth General Purpose Saw Blades

[Richard Coers]

The next time you apply paste wax to the table and rip fence, apply some wax to the riving knife as well. It really helps. You might also change hardwood suppliers, the place you use is not the best at kiln work.

[Michelle Rich]

yes, wood stress, check fence for parallel, and when this happens to me, I stop the saw, pull out the wood...turn it end over end, and start cutting from the other end. Most times this works. A real stubborn board will jam again, but most won't

[Peter Christensen]

I would advise you clamp a board to the front half of the fence stopping at the front of the blade when you rip. Basically making a European style rip fence. This time the wood was pinching. Next time the internal stresses could cause the wood to spread. With the long North American fence the spreading wood can pinch the blade, possible kicking back. Get a dedicated ripping blade rather than the combination blade. They work way better.

[Tom Bender]

I always have a few small wooden wedges handy for a lot of purposes. They are easy to make on a sled. Grab an offcut of Maple or similar 1/2" thick and at least 6" wide and 3" long. Prop it away from the fence 1/2" at the end that is 6" from the blade and cut one off. Remove the prop and cut the next one. Make a few, sand and wax.

[Tony Bilello]

This has absolutely nothing to so with your saw, fence, blade or anything other than the fact the wood is under stress. probably that slab was taken from an area near a crotch.
I would relegate that piece to the wood pile because there is no predicting what it might do in the future as a furniture piece.

[Gordon Stump]

I religiously use a power feeder now to rip thick hardwood. Sometimes a stressed board can kick back and hit a feller in the stomach and cause that feller internal bleeding. Do not ask me how I know this!

[Günter VögelBerg]

It sounds like the wood may be "case hardened". If that's the case the solution is a different wood supplier.

[Dustin Bullard]

I spotted elsewhere that the Freud Diablo blades now come in a super thin kerf option...

A regular kerf blade is 1/8in = .125"
A thin Kerf blade is 3/32 = .0937
The Diablo D1040X (10" General Purpose Blade) should have a kerf of .098 so it should be ok...

However, they sell a 10.25" General Purpose blade with a kerf of .079 and if you somehow ended up with a 10.25" blade it would probably fit on your saw and absolutely explain your issue...

Everyone else here is on point, its probably just unstable wood under stress and your blade is just fine but its still worth taking a peek at the blade... If you can, see if you can track down some calipers and check the thickness of the teeth on your blade as well as the kerfs it cuts and finally the thickness of your riving knife...

I do want to mention that I also use the Diablo 10" general purpose blade as my "I'm not so sure about this piece of wood blade" and save my nice blades for other things and I've never had an issue...

[Marc Jeske]

A great example of a situation for a knee bump off switch.

Marc

[lowell holmes]

Another alternative is :

https://images.search.yahoo.com/search/images;_ylt=A0geKaA9wsVcVk0AckNXNyoA;_ylu=X3oDMTB0 N2Noc21lBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNwaXZz?p =tablesaw+push+sticks&fr2=piv-web&fr=mcafee

[Rich Aldrich]

When not properly stress relieved during the kiln drying, the wood will either pinch the blade or try to spread out after cutting.

I work at a hardwood lumber and veneer plant. Lumber is stress relieve at the end of the kiln dry cycle. The process our kiln dry operator uses is really good for stress relieving and our customers are very happy with the minimal issues with stress when using the wood. I cant go into the details, but I really doubt that it is an industry secret. Some plants don't want to spend the extra time or money to stress relieve. Steam is used to dry the wood.

Our daily production is about 70,000 bdft per day with a 400,000 bdft predryer and 400,000 bdft kiln drying capacity (10 kilns at 40,000 bdft max). Hard maple, soft maple, oak, birch, cherry, beech, and ash are the primary species.

I had a guy with a dehydrating kiln drying process dry 650 bdft and it was really good.

[Tom Welch]

Jack, is your blade a full kerf? like 1/8"? If your running a thin kerf blade like the ones that the box stores sell, then your blade is not opening up the kerf wide enough for your riving knife. You do need a full kerf blade for that riving knife. That said the above condition can still happen with the right set up. But if your set up is correct, you lessen the chance and can avoid problems unless your wood does have a lot of stress in it. Also I would recommend a ripping blade for thick hard woods, but the combo blade can do it, but you sometimes have to rip slower. I do use a Woodworker 2 combo blade, but mine is full kerf. When ripping thick or hard maple I do favor installing my 24 tooth rip blade.

[Jeff Davies]

One out of 100 or 200 boards coming into the cabinetshop would do this. Since we rarely order less than 100 BF at a time , the lumberyard wants to keep us satisfied and stock with major internal stresses seldom gets this far. your supplier may not have this motivation , but I would consider returning it as unusable for its purpose.
Under some circumstances, we had to use what we had on hand. The way it usually worked out was that in the first 8 inches of rip , the kerf would close down , indicating the problem. Then , knowing that you are going to have a bent rip , you might tip out and reset the fence wider to allow jointing down the warp back to straight ( the maddening part being is that once straight , another rip may cause it to bend again ) . Starting the rip again, tip out when the pinch happens, then re rip ,cutting away the pinch. this may have to be repeated several times. Toward the end of the rip, if the kerf is expanding, in the middle, it may split toward you before you reach the end. this can be very dangerous , so be ready and be using a push stick.
At the end of this activity , you have a bent board with a terrible edge cut. if it is oversize, you might be able to save it . I won't go into the remedies , but many of these boards were simply set aside for use as crown boards (bent pieces that can be applied to bent cabinet parts in order to straighten them) many were just cut up to the burn pile.
Some discussion and speculation was made. One gent said that these were all ruined in the dry kiln by reducing the moisture too fast. Another fellow said that these were cut from 'limb stock' that already had stresses that would not work out. Still another said that this happens in walnut because the dry kilns super saturate the logs in an effort to get the heart wood pigment to migrate into the white sapwood, and then not allowing enough dry time after.
I think parts of all of this is true. in addition , I believe that some trees will develop compression forces to counter-act certain natural occurrences and one thing I did notice was that having a bent board and trimming the crown side, might straighten it, but it would not work every time. and if you are making a door, will it stay straight ?, because call backs for a warped door are a bitch.
Once in a while, I would spoil myself ( or I wanted to speed up the job) and order 10" & wider. In hardwood, these boards came from bigger trees, and most certainly the best logs. what a pleasure to rip up a bunch of one inch french mullions or cabinet rails and have them all dead flat and straight.
And conversely , what a wake-up when you rip into a problem board with a 5 horsepower saw, and maybe have an internal shake come loose and wedge the blade trying to stop an almost un-stoppable blade - all of a sudden, its like you cut into a stick of dynamite.
Regards, J J Davies

[michael dilday]

When this happens to me after I get the board off of the blade/knife I move the fence one blade width towards the waste side of the board and make a second cut doubling the width of the cut and continue through the entire board. Then come back and cut to size. This allows the blade/knife to pass thru and relieves the stress before the final cut is completed. Not sure if this is right or not but it has worked for me.

[michael dilday]

yes, wood stress, check fence for parallel, and when this happens to me, I stop the saw, pull out the wood...turn it end over end, and start cutting from the other end. Most times this works. A real stubborn board will jam again, but most won't

I like this method. Will give ita try.