I put on both skins, the hardboard top and even picked out some rough-sawn cherry to finish the project!
I created 3/4” plywood squares to just fit inside of the torsion grid. I placed a row of them in line with my front vice in order to have more depth for potential bench dogs (1/2” MDF + 3/4” Plywood). I also attached a double stack (1.5”) to the bottom skin, where the bench vice lag bolts will attach. This should give plenty of support for those pieces.
I glued and clamped all of those internal filler blocks, and then screwed from the outer side of the skin to hold while the glue dried. Once the glue was dry, I took out the screws. I not only wanted to save screws (hey, they cost money!), but I didn’t want metal in there when I go to drill for dogs and the vice.
I glued on the other skin to finish the torsion box itself. The bottom skin was not as flat as the top, probably because the grid wasn’t perfectly flat on the bottom as I worked from the top. I trimmed the skin flush to the sides with the router and flipped the box back upright.
I checked the top again and found about .010 dip in the center at some places. I had previously found only .005, but either I missed checking some areas or things shifted slightly. I still think that’s pretty damn flat.
I put on the hardboard with drilled+counter-sinked screws, probably about 20. Checking for flat, it was definitely worse. So, I took it back off to re-check the 1/2” MDF skin and it was fine. I noticed on the bottom of the hardboard that where I had drilled through, there were dimples around the drill hole from punching through. So I took a sanding block and knocked those down. Placing the hardboard back down and re-attaching, it was much better; only .010 out – the same as the 1/2” MDF skin.
I got started on milling the lumber for the final edging. I have a nice stack of Cherry that was milled out of trees from my property – this is the first project I’m getting to use them! I chose a few of the pieces near the top of the air-dried stack, so they are pretty badly twisted. It was a challenge to mill them (I’m pretty new at that too) – but I made some good progress and got them ready to attach.
Next up is the final trimming and finish!
-- Morton - http://workshop.scottmorton.com