I’m ‘eyeballing it’ when I speculate somewhere between >10’ and <14’ is both reasonable (realistic for many to build/store) and is predictable to be (knowing wider/higher adds accuracy, but recognizing width adds chain sag and eventually limits height, as well as stock chain length limitations) better than a ‘stock’ frame width. (just under 10’)
I’d recommend the same as @dlang, starting at 10’, simply to have a common baseline for the unistrut frames (the 3rd known build?) and then think about modding from there once you’re dialed in.
Remember that alignment, while there’s room for error, is still pretty important, re: wingnuts, you’re not going to be changing the machine’s dimensions w/o leveling/straight-edge elements afterward. At that point, you’ll probably want to tighten things a little beyond hand-tight, consider that you’re talking about loading full sheets onto the back and on to and off of the machine. imho, a bump with a full sheet is enough to tweak ‘hand tight’ bolts.
I propose that we by pass the entire ‘miter saw sled’ concept and put those efforts into establishing maslow procedures that usurp the need for such an addition by:
- making the sled easier to deal with vis a vie:
- remove/reduce overhangs, friction, resistance, clutter, etc
- rapid re-calibration
- load unload stock
- making the frame rapidly adaptive to multiple thickness of stock
- faster, more accurate.
- extending ground control to produce simple/common cuts, change stock, iterate to ensure only successful active cuts.
Not that there isn’t a lot of work towards all this already, but following the rapid progress of the frame designs, accuracy, software, etc from the early summer beta units to today’s ‘all initial units shipped’.
It is a quite dramatic and rapid change, and it doesn’t have to slow down yet, I think that there’s enough to still figure out as far as ‘best practices’…