I was inspired by Demonx's fret slotting setup after having the displeasure of hand slotting a couple of Cooktown Ironwood boards which came out less than ideal.
After a trip to Bunnings I ended up with a cheap, small table saw. It's only 600W, but that should be plenty for the light cuts of fret slotting. Another compromise with it is that there is no depth adjustment, so I had to work around that. However, it's small which helps in limited space, and at $112 not too expensive. I ordered the fret slotting blade from Stewmac - not cheap, but that's the business end of the setup, so needed to be just right.
I changed the blade. , and measured the height of the blade above the table. (sorry about the poor photo).
I figured that I would make a larger auxiliary table to go on top, and a sliding table above. The combined thickness of those need to be blade height minus slot depth.
My careful calculations didn't work out - too much margin for error and I ended up with no blade sticking out above the sliding table.
I remade the auxiliary table with offcuts of thinner plywood, and melamine coated chipboard as a frame to hold the auxiliary table to the table saw.
and then made the sliding board with a fence at 90 degrees to the blade.. You can't see in these pictures, but the sliding table has runners that hug the auxiliary table and keep the movement straight. I extended the runners past the back of the table so as it gets pushed forward, the runners stay engaged.
The slot for the blade in the auxiliary table was made with a router, and in the sliding table it was made by lowering the sliding table over the blade while it was running, and then enlarged with a router. The sliding table was then slid forward while the saw was running so it cut all the way through to the back of the sliding table and left a notch in the fence for blade clearance. At this stage the blade was sticking up too high, so I stuck plywood shims on the auxiliary table to raise the sliding table.
. And Voila!. A few test cuts and fret placements to check the depth, and I was ready for a whole board.