When I am ripping 3/4 cherry on a Porter-Cable model PCB270TS table saw the board wants to rise and has to be held down. I am using a 40T combination blade. The blade seems parallel to the fence and the splitter. I can measure the fence to about 0.006 wider at the back of the blade as compared to the front of the blade. The cut is smooth.
I can’t think of anything else to look for that might cause the problem but to keep pressure down on the board is nerve racking to say the least!
Any suggestions as to the cause?
Mike
Replies
Boards will have a tendency to lift when ripping on any saw. Your saw is a light weight so it may be lacking in power, your blade is probably dull and you may be feeding too fast. Combination blades are a compromise. Change the blade and slow down for starters. Sometimes the kerf can close up as you rip, pinching on the blade.
Too many teeth creating too much drag. Use a blade with fewer teeth. There are many factors in blade selection, but tooth count is crucial. To over-generalize a bit, fewer teeth = faster but rougher cut whereas more teeth = smoother but slower cut. This holds true for router bits, shaper cutters or virtually any woodworking operation. You might also try raising the blade up some to increase the attack angle.
Mike,
Lifting happens at the back of the blade where the motion is upward. It's likely you're either ripping a board with internal stress that's causing the kerf to close up as it passes by the blade or your fence is misaligned. Are you using any kind of splitter? How do you align your fence?
The splitter is not aligned with the blade.
It is not "normal", to have uplift, as the other responders are saying. It is almost always a sign that the saw is not properly set up.
The wood is trying to lift because the wood is contacting the back of the blade. There is no other force that will lift it. Now you need to figure out why it is making contact. My first guess is the splitter isn’t aligned correctly.
Try this for a start: Raise the blade as high as it will go. You want the blade high so it is making the narrowest kerf it can. Start a cut in a piece of scrap, get the piece far enough into the cut to be just past the center of the blade, (about four inches). Stop there and turn off the saw. Pull the piece back and lower the blade completely. Now run the piece against the fence until you get to the splitter. The kerf should line up exactly with the splitter. If it doesn't adjust the splitter so it does.
Once the splitter is aligned, check to see how the width matches the kerf. It should be just slightly snug. If it is not, get some clear Mylar packaging tape and apply it to the splitter. Mylar is tough, smooth and slick. Apply a long piece so you can “fold” it around the front of the splitter, and wrap it back so there isn’t an edge to get pulled loose by the board. The Mylar tape will add a little thickness to the splitter, while decreasing the friction. Keep adding the tape until the fit is just a little snug.
Now make a test cut and see if the problem is still there.
Board lift
Many good posts here, some fair.
some questions.
Is the blade SHARP ? Is the blade clean ? Make of blade ? Are you getting any burn marks on either side of the board ? What is the blade height when you measure the .006 How High are you running the blade when making the cut ? Use a dial indicator for squareness of blade to miter slot and fence ?? Tried the cut without the splitter ? Tried a dedicated rip blade ? Tried a slower feed rate ?
With out these answers we could go on for ever guessing.
Not trying to be a wise ass (!)
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