Hi! I have been troubleshooting my Grizzly table saw and I am stumped.
I am ripping 8 foot pieces of oak and everything is going great until the end of the cut. Once the front of the blade gets through the end of the piece of wood and I have to push the end of the wood entirely past the back of the saw, I have a problem. The wood is pushing into the saw blade and the last 4-5 inches of the rip cut are not 90 degrees. When I get the wood past the saw I can see that the wood is visibly pushing the riving knife to the left of the blade (my fence is on the right of the blade). If I stop the saw as soon as the front of the blade passes through the end of the wood and let the saw come to a stop I end up with an acceptable cut. The pieces I am ripping are joining up nicely.
I have watched numerous table saw alignment videos trying to figure out what is wrong. One thing I discovered using a dial gauge and a jig for the miter tracks is that my fence has a slight deflection in the middle of about 5/1000 of an inch. I can align the front and back of the fence to within 1/1000 of an inch however the middle however the middle would be 5/1000 further away from the miter slot. I have tried adjusting the fence so it angles away from the blade by 5/1000 of an inch but that does not help. Also, the last 4-5 inches of the wood (when I push all the way through) is visibly at an angle so the issue is way more than 5/1000 of an inch.
I don't notice this issue when I rip shorter boards so I assume that my misalignment is building up over the length of the long boards. I am using an outfeed roller stand and I have a 48" flat aluminum bar and as far as I can tell everything is perfectly level with the table.
Thanks for taking the time to read this and thanks for any suggestions.
I do not have a riving knife on my saw. Therefore, I am able to use a feather board on the outfeed side if the blade when I am cutting a long board. This keeps the board gently pressed against the fence all the way through the cut. Do not know if this would work with your saw configuration.
I had that problem ripping long boards. turned out it was being deflected slightly by the roller stand. I now use a permanently attached (hinged) outfeed table, so when I move my table saw in my small shop... it stays perfectly aligned with the table. When necessary... I can fold it down or up. Being that the outfeed table references off of the table saw and not a possible un even floor, made the drifting go away.
A longer fence or fence extension and an out feed table will take care of this problem. You need the fence extension to keep the board feeding straight and with your shorter fence it is no longer being guided as you reach the end of the cut. A long straight board that is attached to the face of your existing fence will work. DO NOT use a feather board behind the blade. It will close the kerf and result in a possible kick-back. Make certain that your fence is truly parallel with the blade and miter slot of your table saw too, not just close. It needs to be adjusted to be about as parallel as you can get it. A few thousandths wider at the out feed end is sometimes better. Use machinists measuring tools like a dial or digital caliper for this kind of measurement. A ruler or scale isn't good enough.
A longer fence or fence extension and an out feed table will take care of this problem. You need the fence extension to keep the board feeding straight and with your shorter fence it is no longer being guided as you reach the end of the cut. A long straight board that is attached to the face of your existing fence will work. DO NOT use a feather board behind the blade. It will close the kerf and result in a possible kick-back. Make certain that your fence is truly parallel with the blade and miter slot of your table saw too, not just close. It needs to be adjusted to be about as parallel as you can get it. A few thousandths wider at the out feed end is sometimes better. Use machinists measuring tools like a dial or digital caliper for this kind of measurement. A ruler or scale isn't good enough.
When you use a feather board behind the blade you do not set it with any pressure on the wood. It is set so that it just touches the outfeed wood and keeps it from drifting to the left. You could also clamp a piece of wood on the saw table to achieve the same result. A feather board is just easier to mount.
Thanks for all of the suggestion! Considering all of the times I have spent checking alignment the longer fence makes sense and is the next thing I will try. I really spent time shimming my roller stand to get it level (thought it is 1/8" lower than the table) but I will check that again.
Is your roller stand a solid tube that rotates. (like a rolling pin), or is it a set of free rolling ball bearings? If it's the first, the roller must be perpendicular to the board you are cutting. If it's slightly out, it will try to move your board to one side or the other. I learned this the hard way...
I have watched numerous table saw alignment videos trying to figure out what is wrong. One thing I discovered using a dial gauge and a jig for the miter tracks is that my fence has a slight deflection in the middle of about 5/1000 of an inch. I can align the front and back of the fence to within 1/1000 of an inch however the middle however the middle would be 5/1000 further away from the miter slot. I have tried adjusting the fence so it angles away from the blade by 5/1000 of an inch but that does not help. Also, the last 4-5 inches of the wood (when I push all the way through) is visibly at an angle so the issue is way more than 5/1000 of an inch.
Don't get caught up thinking like a machinist. Table saws aren't manufactured to be that precise. Getting concerned over a few thousandths is pointless when dealing with woodworking. Align your blade parallel to the miter tracks, align the fence so it deflects slightly away from the blade on the outfeed side of the cut(otherwise your work gets pinched between the blade and the fence) and you should be fine with saw setup. The rest is like others have said...likely that your roller guide is the culprit.
Does your fence have a plastic , nylon or whatever face on the steel tube? Have you tried to shim the face til it is acceptable ? My saw is an older version of yours, no riving knife and tilts right. I removed the nylon face and replaced it with "Fin board". This is a 13 ply birch plywood . The nylon face was not flat across the length. I did not know if it could be jointed flat like wood. I had the plywood on hand. I checked the fence after replacing the face, no appreciable deflection was found. Try Baltic birch plywood and shim if necessary. .5000 is a lot, printer paper is .4000
and you can feel the difference .
One thing I do not understand, you say the last 4/5" is not square. Do you mean that the end of the cut is not straight ? I have never used a saw with a riving knife, actually haven't even seen one. I used to mount a hardwood wedge on the insert to keep the kerf from closing up on rip cuts. I imagine a riving knife does this too.
I generally use a power feeder when ripping so the blade guard and splitter have been removed. The wedge does a nice job of keeping the kerf open.
mike
I strongly suggest you abandon the roller stand! They are not appropriate as an outfeed support because unless perfectly 90° to the blade kerf or a slight skew will track the board one way or another.
A riving knife or spiltter are an absolute must for me this is not debatable.
If you want to use a roller stand, use an omnidirectional like the one mentioned by RonBenson.
I only use mine far after the outfeed table to just catch the pieces that are already past the rear of the blade, so no influence on the cut being made. A smooth, solid outfeed surface is what I have found to be the best. Mine extends about 48" from the rear of the table, so plenty of support for most cuts and for long rips, the roller stand comes out.
:|
I agree with RonBenson. If the roller pin variety is not perfectly perpendicular to the blade the rollers will pull the wood toward/away from the blade, especially long boards, even if the rollers are the same height as the table. Notice you mentioned you did not have problems on shorter boards which probably do not touch the roller stand.
How is the sharpness,type, and quality of your blade? What blade height are you using? You should not have to work that hard. The length of the fence should not matter. Your blade should run dead parallel to the miter slot, I like my fence open about 1-2/1000 on the outfeed end. Have no scientific evidence it makes a difference, just the way I was taught. Blades can start to deflect when they get hot, which would be the end of the cut. I would make sure you have a good, stable, sharp blade. U have always used Forrest Mfg. blades, the Woodworker II is a good choice. They are pricey but you will have it for ten years. I would also try, if you have not already, raising the blade well above the stock.
For long rips I tend to go half way, lift the piece off, flip it around and over, then restart from the other end. That way I end half way and don't have to deal with an 8' piece hanging off the back of my saw.
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