From time to time, I like to stop all jobs in the workshop to fine tune. This could mean sharpening tools or it could be repair or re-adjusting things to make them work better. Recently I had a good look at the where the Riving Knife and the Splitter are attached to my table saw. What I noticed is that in the lower part of the attachment block there appeared to be some bolts that looked like, if they were taken off, I might be able to fix the positioning and alignment of my riving knife and splitter.
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I don't use my Riving Knife very often but I DO use my splitter a lot because it helps with the dust extraction and keeps the shop cleaner and more dust free. Every time I have to take the splitter off, it annoys me that the block it sits in is out of alignment and I have to use shims in order for it to work. I paid a lot for this saw and that one thing should have worked better than it does. I should not have to use shims that fall off into the base of the saw every time I have to take the splitter off to use a table saw jig or cut vertical wood, so it's time to fix this ...
The purpose of a Riving Knife and a Splitter is essentially the same thing, to help prevent kickback when cutting natural woods that happen to have hidden stresses in the wood that make the wood want to pinch back together behind the blade as it is being cut. This can be a very dangerous situation as the table saw blades will want to force the wood back, as in "kickback" because the pinched wood is grabbing the back of the blade.
Where this gets seriously dangerous is when you have a very powerful table saw with a 3 or even a 5 horse electric motor and you are ripping thick, 2 inches or better, natural wood with built-in tensions in the wood. This saw and wood combination can be very dangerous to work with and a splitter or riving knife is essential.
Another by-product of splitters and riving knives is helping to reduce kickback for people cutting shorter pieces of wood and using those "chicken's foot" or "birds mouth"push sticks. These push sticks on their own can make the wood twist sideways as it goes through the saw, then ride up on the back of the blade and get thrown back toward the user. That is why I NEVER recommend their use to my students, the best push stick to use is the one with a long front hold-down and vertical attached handle that the user has control of the wood they are pushing through the saw.
The first step was to see if the metal block that has the slot that holds the riving knife or splitter actually does come off and to my delight, it is only held on with a couple of cap screws that an appropriate sized Allen Wrench will easily take off. I could see that the block and the carcass of the saw both had nice large flat areas and by making some suitable shims and re-attaching the block, it appeared that this would fix the alignment problem ... something the manufacturer should have done before shipping the saw.
Since I was already using brass shims and knew the thickness, it was a pretty easy task to make 2 new ones, but in a different shape, that matched the attachment block and the saw frame. I cut out the squares of brass, drilled a couple of holes for the cap screws to go through ... tested them and they worked fine. Next, I had to re-attach the block, with the brass shims to the frame of the saw, with after a bit of coaxing, they managed to go on and tightened down nicely.
All that was left now was to see if the alignment was correct, hopefully, the shim thicknesses were the same and the new shims would align properly.
To test, I installed one of my full kerf blades just to make sure there was no flex in the blade, then I took a steel rule and ran it across a couple of outside teeth on the blade and aligned them with the riving knife at the back. They all lined up perfectly.
This means that now I can take my splitter or riving knife on and off the saw any time and with any blade, thin kerf or full kerf and will not have to use shim or re-adjust anything and the outside of each blade will align perfectly because the splitter and riving knife are aligned to the flange of the table saw blade. A safe easy solution that will ensure the shop will minimize dust and the saw will be more convenient to use.
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Copyright Colin Knecht
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