Got a little bit done this weekend. It’s getting late, so I’ll make it quick.
Each table started as 3 layers of 1/2” (12mm) baltic birch, laminated with epoxy in my vacuum frame press.
I laminate them face down so that the top face would be flattest.
Once I pulled them from the press, I noticed that there were some thickness variations in the plywood that left the backside less than flat. So, I put them on the CNC and machined about 1/32” off the back side to flatten it out. I then flipped it over and took .01” off the face to get rid of some minor high and low spots.
While the tables were in the press, I cut the links for the parallelogram on the CNC. I drilled 1/8” holes in one of them to mark where the rods were to go for a template. I want to drill the holes on the drill press, because my flimsy cnc can’t cut perfectly round holes, which I really need here. The steel rods need to fit very tightly into the holes, so that the table is firmly mounted. I did a test cut with my 1/2” forstner bit, and it was close, but just a little too loose. Since it’s an old cheap Black and Decker forstner bit, I chucked it into my drill, and ground the diameter down a little on my 6×48 belt sander. Another test hole, a little more grinding, and it was ready to go. At the drill press, I located the part with an 1/8 drill bit, clamped it to the table, and swapped out the forstner bit to drill the hole. Repeat two more times, and I have my master template.
Once the tables were machine flat, about an hour of creative table saw work got them to their finished state.
Next step was to start drilling the stainless steel. I ended up with 14 gauge, for both the top and bottom, because I got a really great deal on it. Both bottom plates were drilled and countersunk, and then the top plates were notched with an angle grinder. I’ll drill the top plates tomorrow.
Bottom plates were then epoxied and screwed to the bottom of the tables. The original plans used aluminum foil on the bottom to keep out moisture, but I wanted the same thing on the top and bottom so the steel could be permanently glued and screwed in place.
Installation of the top plates will be a little more difficult. I noticed that when I screwed the bottom plates on, that the screws created a roughly 3” dimple in the stainless, almost 1/32” deep. I knew this would happen, but I didn’t think it would be so severe. It’s not a problem on the bottom, though, as it’s just a balance sheet to help keep the tables flat.
The top sheets need to be glued in place with no screws, with the screws added after the epoxy has cured. This will prevent the dimples that I got on the back. To do this, and keep the stainless flat, I’m going to clamp the two tables together face to face. In order to hold the steel in place, I’ll attempt to use two screws at the outside ends of each table only, with light pressure, just to hold them in place. If I see any dimples in my dry run, I’ll revert to holding them in place with duct tape. I’ll drill and coutersink tomorrow, and probably glue them on Wednesday.