The Kapex is a great miter saw, probably the best around. But in my experience and from reading on forums it is prone to kick backs. At least mine is, i bought mine used some years ago and at some point noticed the fence was not completely flat, but
rather concave with a 0,6 mm gap in the center. Enough to cause frequent kick backs, as when the cut is made the wood gets pulled against the fence and pinches the blade. this causes a violent kick back, especially on thicker and wider boards. On the image below you can see the gap in the center.
A video of the construction can be see here: Youtube.
I had two options, order a new fence and hope it was flat, or add a wooden jaw on the fence that would correct the problem and even improve other aspects like reducing the clearance between the fence and blade.
Taking off the fence is pretty easy, just slide out the upper fences and unscrew the 4 bolts that hold the fence. What i did then was prepare 2 pieces of quarter sawn beechwood, any hardwood will do. But i used quarter sawn to make sure the fence stays as flat as possible. You need two pieces of 120x280x10mm. reassemble the fence parts together and hold the wooden board against the fences to draw out the shape of the original fences and cut it out with a bandsaw. If you use a jigsaw it would be better to make the boards longer so you can clamp them for cutting, and cut to final length afterward.
At the rear of the fence i made a 30x1mm rebate on the table saw so that the bottom of the fence doesn’t touch the fence base wich would make the fence hard to slide sideways. For this i had to remove the riving knife of my table saw which is pretty unsafe. Looking back i would have done it on the router table.
I countersunk the holes at least 6mm deep so that the screw/bolt head would not stick out on the front. I used 5×40
mm bolts to hold the fence jaws in place. Then i simply made a few passes of the whole fence with wooden jaws on the jointer applying light and even pressure until i had about 8 mm of thickness left. Make sure the bolt head can’t touch the jointer knives! Then i passed with a chamfer bit and a router around all the edges. The chamfer on the bottom will leave space for the sawdust, with the original fence you have to constantly blow away the dust, otherwise it gets in the way and stops you from making exact cuts.
Above you can see the finished fence, i also used the opportunity to make a zero clearance insert. I applied two coats of boat varnish in the wood in the hope that it will stop the fence from moving too much as my kapex is usually stored in non-insulated spaces.
Above you can see it in place on it’s bench, i did a few test cuts with thick and wide boards that would have been hazardous before, but they went flawlessly. An unexpected result was also that the dust collection seems to have improved even more, here is much less open space around the blade and it seems to force the sawdust to fly upward into the rubber dust collector.