Again with addition to an old thread, but what the hey!
I went looking for a sturdy knockdown
sawhorse and didn't find a design that I liked. So it was off to Google Sketchup!
Here's the build in sketchup...
Top rail length is 4' so just scale it and take measurements from there on.
About 25 bucks material for the pair, easy to build, two bolt knockdown, very
sturdy, relatively lightweight.
The 2X10 provides a decent amount of angular anchoring for the saddle of the legs. The 3/8 bottom bolt remains in place and the top one is removed for take down and storage. Slighty more expensive than an all 2X4 design, but many times sturdier. A 2 X 10 X 8' prime board at Menards is about six bucks (there's always a prime grade single board to be found in the "construction grade" stack if you search a bit). Four 2 X 6 X 8' or 2 X 6 X 6' boards another 15 bucks or so. Most of us have the 2 X 4 just laying about for the top rail. Four 3/8 X 12" zinc plated carriage bolts ought to be another six to eight bucks, unless you can find a length of threaded rod cheaper yet. If you recessed the hole just a tad, one 36inch rod would be just
sufficient for all four bolts.
Top rail is 2 X 4 X 4'. Legs are 2 X 6. Total height is approx 31". Longitudinal stance of leg is 10 degrees from vert. Transverse stance of leg is 20 degrees from vert.
Bolts are 3/8 X 12" carriage type trimmed to fit. Wing nut on the top one would make it that much easier to dis/assemble.