As usual, all my projects take far longer than they should. But, I finally got my phenolic plates epoxied and CNC routed a couple of them. They’re a full 3/4” thick, and very rigid. I probably didn’t need 10 leveling screws, as the plate doesn’t seem to flex. But this one only has a 690 in it. When I do the 7518, maybe it’ll have a little bit of flex. But, I doubt it.
I’d never seen the Incra leveling system before, but decided to go this route after reading this blog.
One of the plates I epoxied was a little bit unflat, so I used that for test cuts. It ended up being a little loose, so I added .002 for the next one, and it fits like a glove. To make sure the holes lined up in the table, I used the plate as a template. The holes for the levelers are routed 3/16” D. I used a 3/16 drill bit, and drilled through the late into the MDF. To tap the holes, I cut the head off a 1/4-20 bolt, chucked it in the lathe, and filed a taper on the end. Using a cordless drill, I quickly taped the 3/16 holes. This gives a very strong thread in the MDF. I actually had to use some wax to get the screws to turn smoothly, as the fit is very tight. The screws are Stainless button head, btw.
Getting precise holes for the router turned out to be a bit difficult. The holes in the plate are 3/16, which leaves zero slop for the 10-24 screws. I measured it as close as possible, but it was a little off. Then, I used a different technique, and came up with a hole circle diameter of 4.642. It’s not perfect, but it’s very close, and works.
Next step is to route a base for the Incra Jig, and put about 5 coats of poly on it and the auxiliary fence. Then, It’s ready for use.
-- Gerry, http://g-forcecnc.com/jointcam.html