: I think you are using too small of a sled. You have no support for the
: cut-off wedge, and your 'fence', which backs-up the main part of your
: board, stops too far from the blade. And the blade isn't covered.

First I agree the blade being covered would be a good thing. I don't have a good way to do this with the sled and clamps. I am all for good guards but with the jig it's just won't work.

I strongly disagree with supporting the cutoff on a sled. I was using a wide sled that spanned both sides of the blade and letting the cutoff rest on it. I think that is why I have a mangled thumb too. There are two things that could happen and these are why I will never use a sled again for this operation.

1. The cutoff (if small) can vibrate behind the blade. If you pull the sled forward you pull the cutoff into the back of the blade and instant kickback. "I THINK" that is what happened to me. I didn't see what happened but I am betting that is it.

2. Even if the part doesn't get behind the blade you can drag it back by the rear of the blade and that increases the chance of a kickback. (If you have never paid attention the back of the blade is spinning upwards and will lift/throw the part)

After a lot of looking and thinking while waiting to get back in the shop I have decided that this is a bad idea and 'I think' but can not prove that a sled increases the chances of a kickback cutting scarfs because of pulling the cutoff back into the blade. Yes you shouldn't do that and should stop, remove the part and then pull back. But it is always that moment of inattention that gets you so why risk it?

What I do know is I will never use that design on a scarfing jig again. At least this way the part falls off and is not drug back toward or against the blade. Yes there is chance of kickback still but I think it less.

So far I have only had the one slide forward and get pulled down by the bade. I have yet to have one slide toward the back of the blade. Most just fall on the table and sit there. Some move away from the bade and one or two moved forward. None have headed toward the rear of the blade.

FWIW I think a RAS is the best tool for this. But mine is against the wall and it is a old cast iron monster that is not mobile. So I can't cut out knots in the center of long boards with it.