Platforms: weight vs strength, 2x6 vs 2x4 best practices

[bobgaggle]

I once saw someone rip 3/4 ply into 5 1/4 strips for deck framing, claiming it was far cheaper than #2 pine.

I've built many many many platforms that way. Depending on the plywood you buy, it may be cheaper, straighter, easier to work with. Lots of pros and not many cons for the plywood framing method. As long as you understand the expected loads and leg appropriately, I don't see a downside to it...

 

[RonHebbard]

We frame flats out of ply for dimensional stability, and I would do platforms that were sitting on the ground. I would not use ply for platforms legged up in any manner, because I don't trust fasteners into end grain of plywood for structural uses.

@kicknargel Surely if you're assembling parallels you're using at least 8 or 12 2" back-flap hinges, mostly secured with 2 flat head wood screws plus one flat head machine screw and nut or T-nut per hinge half with zero fasteners into any end grains.
Toodleoo!
Ron Hebbard

 

[Chase P.]

Where on earth do you guys store all these monsters? Doesn't anyone build parallels any more?

Parallels for the win! We used these in college, but I haven't seen a single one since. We also had stock knee walls, both for flat platforms and rakes. It was opera. So many rakes.

Does anyone have an opinion on using 5 1/4" wide 3/4" ply as the box/framing of a platform? I've seen it done, but have never gotten an accurate weight comparison, or a solid opinion on the strength.

Edit: Just saw and read the additional pages of responses on ply as framing. I got distracted and excited by parallels. I'd still love more input on the ply as framing concept.

 

[RonHebbard]

Parallels for the win! We used these in college, but I haven't seen a single one since. We also had stock knee walls, both for flat platforms and rakes. It was opera. So many rakes.

Does anyone have an opinion on using 5 1/4" wide 3/4" ply as the box/framing of a platform? I've seen it done, but have never gotten an accurate weight comparison, or a solid opinion on the strength.

Edit: Just saw and read the additional pages of responses on ply as framing. I got distracted and excited by parallels. I'd still love more input on the ply as framing concept.

@Chase P. When we built our 8" and 1' parallels as 4 foot x 8 foots with 3/4" ply for framing, we windowed the sides and ends with a sabre saw to reduce weight, create hand-holds and make feet. After roughing out the openings with a course sabre saw blade we finished all of the cuts with a 3/8" ball-bearing piloted, round over bit to make quick work of finishing all of the edges that would be subject to handling. This worked well for us in 1973 and, with the addition of many, many coats of flat black paint, all of the parallels were still in service the last time I saw and touched them somewhere around 2010. They definitely had a few miles on them but were all still in serviceable condition. (Yay IA 129 with much help from Jimmy Burns and IA 58's opera shop arpenters.
Toodleoo!
Ron Hebbard.

 

[Chase P.]

@Chase P. When we built our 8" and 1' parallels as 4 foot x 8 foots with 3/4" ply for framing, we windowed the sides and ends with a sabre saw to reduce weight, create hand-holds and make feet. After roughing out the openings with a course sabre saw blade we finished all of the cuts with a 3/8" ball-bearing piloted, round over bit to make quick work of finishing all of the edges that would be subject to handling. This worked well for us in 1973 and, with the addition of many, many coats of flat black paint, all of the parallels were still in service the last time I saw and touched them somewhere around 2010. They definitely had a few miles on them but were all still in serviceable condition. (Yay IA 129 with much help from Jimmy Burns and IA 58's opera shop arpenters.
Toodleoo!
Ron Hebbard.

That's a significant run for any piece of scenery! I'm curious how a platform would hold up over a parallel. Platforms are basically glued butt joints with a few fasteners, while parallels use hardware to make those corners. I know ours in college were all stove bolted through the hinges into t-nuts on the back. It seems like that would offer a lot of additional corner strength.

These days, I guess it'd be pretty simple to have the shorter parallels zipped out on a CNC router, bolt holes and all. They'd basically be IKEA scenery, only less MDF and longer lasting.