John,

I have a rip fence extrusion that is shorter than the normal one specifically for bump-stop use. ?You can buy it from Felder?.

When using this fence with a 300mm blade, it’s impossible to get the fence extrusion to overlap with the blade since it isn’t long enough, but it works well as a bump stop.

So to use this as a bump stop and defeat the 3mm gap that the positioning system won’t go beyond, install the fence extrusion with the wide face down, and push it far enough forward that the limit switch is tricked into thinking that fence is installed in the vertical position as shown below:

With the fence in that position, you can enter the value 42mm into the rip fence position on the heads-up display, and then push start. ?(The fence extrusion is 42mm taller than it is wide). ?Once that is done, pull the fence extrusion back over the limit switch, and lock the fence extrusion to the rip fence housing, and you’ll see the fence is now at the Zero position relative to the right side of the blade kerf. ?

As long as you are using a fence extrusion that isn’t long enough to overlap the blade when pushed forward enough to defeat the limit switch, you don’t risk getting the blade trapped and forced into and bending your saw blade. ?This is the reason I use the short fence. ?You can do the same with the long fence, but instead of pushing it forward, you’ll remove completely by pulling it backward, then set the display and housing, then reinstall the extrusion. ?Hope that’s clear. ?The short fence extrusion is for safety.

Let’s take the case where you want to have the bump stop positioned for a 1mm trim cut off the edge of a door. ?Assuming the blade kerf width is 3.3mm, you’d push the fence forward so the limit switch is NOT activated, then enter 39.7 (42mm - 2.3mm) into the display, push start, the fence housing moves, pull the fence extrusion back over that limit switch and lock it in position, and you’re display will read “ -2.2 “ leaving 1mm of the blade kerf exposed for the trimming cut. ?Of course at this point, you’d push your material against the fence extrusion and lock it to the slider with clamps before proceeding with the cut.