So the plan from here was to start assembling the slats onto the trusses, to make sure everything lined up ok, and to then "lock in" the truss spacing before welding could begin.
For this stage of the assembly, everything would need to be upside-down, with the table top against the ground. I put some lengths of tubing down first, to make sliding the slats around a bit easier. I then laid everything out, and tried to get things relatively aligned.
Everything looked pretty good, but I underestimated what a PITA it would be to get my screws and washers down through the larger access holes and into the aligned tapped hole of the slat. Remember, I'm working downward here- the screw wants to fall off of my bit in this orientation. At first I tried a magnetic hex head tip, but the screw and washer kept falling off and getting lost inside the truss. Then I got smart and gooped up the screw, washer, and hex key with grease. This worked well.
As I'm working down the trusses, I can feel the tolerance stack up effect- even though I thought I did a pretty good job with my spacings. The first slats were really easy to align
to the trusses, but towards the end I really needed to force things into place. A big hammer is always helpful! There were a few that just wouldn't go, so I ended up drilling out the holes in the truss a little more- which worked fine- just bruised my ego a bit
I did run into one set of holes which, no matter how hard I tried, just wouldn't seem to go. They looked sufficiently aligned, but I just couldn't get a screw started in them. Turns out I had forgotten to tap those holes- d'oh! I took me an embarrassingly long time to figure that out... anyway, I'm always happy when there's a simple solution, even if it means I'm an idiot.
Here's all the slats, successfully screwed into the 3 trusses.
Next up, I can start cutting and welding the frame- finally.
Jake