[AUSTINMACHINING]

Thought this might be useful to others.

I occasionally have the need to machine large (22" x 23") pieces of polycarbonate. I design the part with two locating pins centrally located so I can machine one half, rotate and do the other half while maintaining tight tolerances. In the past I have used MDF sheet stacked high enough for the tool to reach the part using those T slot clamping sets with all the pieces. I call them desperation clamps because hate fiddling with them, I have to be desperate to use them. Setup seemed to take forever. I came up with a quickly removable fixture plate using left over extrusion from my enclosure build as riser blocks. I drilled through holes in the extrusion, machines some t-nuts from aluminum and used two pieces of melamine shelving screwed together as the table. I counter bored holes deep enough for plenty of machining clearance on the 3/8" through bolts. I then machined some rocker clamps (?) from a 12" long strip of scrap aluminum. I machined slots and 3/8-16 threaded holes. Then cut into individual clamps using the band saw. I used 3/8" button cap screws upside down to serve as the rocker for the clamp, then drywall screws to clamp down the stock. I put an indicator in the spindle and was really pleased to see that I was getting .002" of flatness across the 22". After the machining was complete, part removed and the table still clamped down, I counter bored holes with a hand drill and ran some self tapping screws to captivate the melamine table to the extrusions. Now when I remove/install the table, everything is one piece. No loose fasteners. Just loosen up the 6, 3/8" bolts and slide the table off the bed with the T-nuts still attached.