@vangmountain

2 months ago

The issue is a matter of physics and the solution does not require one to get closer to the blade. A force applied line parallel to the board will never generate rotation like he shows here. The reason it rotates is due to a net torque generated by friction forces from the table and the saw which run to the left of the push block in the opposite direction and are parallel to the force from the push block. It's this combination of force that causes the rotation, not merely the location of the push force. Yes, shifting the push force left helps because it shifts some friction forces to the right of the push force putting it closer to a state of equilibrium. The danger of this the push block and finger get close to the blade. Physics tells us how to reduce or minimize this net torque. The way to do it without getting close to the blade is to control the top of the board. Pushing from the rear is susceptable to rotation. Pulling from the front is less scusceptable. Your push block design is critical. The angled handle is correct because it induces a downward force component onto the block rotating it into the wood/table if you push down at an angle. The fix is to arch your push board in the bottom so the front makes most of the contact and the rear makes only a little. Maybe a 1-1.5" contact surface at the top and only say 1/2" or so in the rear. Adhere a grippy surface like rubber on it so it compresses as you push giving you better grip. The arch prevents surface contact and transfers this torque you generate into a concentrated down force at the top of the board which is what you want. Think of the contact point of your push board at the rear that does the pushing as the fulcrum of a rotating arm which is the board you are cutting. To control this arm from rotating, we want to apply a force on the arm(the cut board) as far away from the fulcrum as possible. This means apply as far up the board as possible. When the board is cut flat like this, the down force generated by the torque on the push block is spread all along this flat surface. We want this force as faemr up as possible and we want it concentracted. The arch design does this for us. In this way, we are applying a push from the rear moving the board forward and a down force at the top of the board generating friction at the top that is going resist the torque generated by the friction forces and the saw which both are opposite and to the left of the push force. FYI, i do not own a table saw, but I understand the physics of what causes the rotation so it's easy to figure a solution for it. This accomplishes the equivalent of putting your fingers at the top right of the board and pushing the top, not the back of the board. It incorporates it into your push board design. Give it a try people and I bet you it works and is safer than moving closer to the blade. It's just a minor modification to your push block design. Adjust the arch till you have the grip that you need. It might need to be 2 inch at the top. You can also adjust the angle to apply to the handle of the push block. Higher angle will generate more down force giving more grip. Try it out. Cheers!

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