Frameless foamie?

[jae]

So I'm sure I've brought up more than once my interest in making an ultra-light camper to pull behind my motorcycle. I just started assembling my ~800 lb capacity (8" wheel) Harbor Freight trailer and I'm unhappy with how heavy it is, before the sleeping quarters have even been considered.

SO... what would be needed to do a "frameless" setup, along the lines of the ultralight chassis? For the floor, I'm kind of thinking 1" foam skinned on the bottom (outside) with canvas, and 1/4" ply on the inside, and then using suitable peices of aluminum 2"-3" wide to help spread the load where the floor would be bolted to the running gear and tongue.

If any of this is unclear, I'll see if I can get something sketched up in SolidWorks a little later during my lunch break, and as always, criticism and suggestions are more than welcome.

[GPW]

Jae, a little sketch would be Nice !!! Sounds perfectly reasonable , what you want !!!

[jae]

After going back through the plans gallery, I guess what I'm really aiming for is a foamie version of the Pico-Light. As long as the tongue and axle are tied together, and floor properly secured, I'm thinking this could work... I'll have to work with the material properties in SolidWorks, but I'm kind of wondering if there would even be any weight savings to going full aluminum on the bracing/tongue and just bolting it all together, or if I'd be just as well off to go with steel and weld it (I'm assuming the off-the-shelf torsion axles I'm looking at are steel)...

[jae]

Obviously a LOT of tweeking, measuring, etc. that would need to go on here, but I'm thinking about using the Northern Tool torsion half-axles, tied together (and positioned) by some angle iron (the two vertical lines shown between tires), and then two longer pieces of angle going to a central tongue.

On top of this I would likely have some type of small tongue box, probably more for looks and a small 12V battery than anything.

For reference, that floor is 42" wide, 84" long at the furthest point of the arc (21" radius)

[jae]

My next thought is instead of canvas on the bottom, to skin the foam on both sides with 1/4" ply. I would of course prime the wood some how under the trailer attachments, but then once it was all assembled, the trailer and entire underside would be coated in something like truck bedliner to seal the wood and increase finish durability.

[KCStudly]

I think you could do the bottom of the floor in foam and canvas like you plan. Just have hard block pads (good ply built up; or select solid oak or maple) where the foot print of the axle mounts and tongue tie in points will be; anti crush blocks if you will. You could even build a frame of 5/4 stock x 3 or 4 in an 'A'-frame shape, attach that to the underside of your deck then back fill with foam. That would give a nice solid tie in between the steel triangle and floor, without adding too much lumber.

I would worry that smaller flat plates just on the bottom would crush the foam over time, allowing the fasteners to get loose.

When you do get to the detailed measurements you will find that the torsion axle mounting points are actually in front of the axle center line; they have trailing arms that place the wheel centers behind the torsion pivot point.

[Lonewolf42301]

Check out this build: http://www.goldbrand.info/index.html I too am in planning stages for a motorcycle camper and will start my build this fall (too much to do this summer around home). I am planning a lighter floor then this guy did too with a composite of foam,fiberglass and aluminum. Yoy mentioned 2 layers of 1/4 in ply... 1/2in of ply gets pretty heavy....













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[jae]

Lonewolf: That build is what got me thinking about it. Rule of thumb that I've found is that a 4 x 8 x 1/4 sheet of plywood is ~ 25 lbs, so by the time I cut it to the size I've planned, each sheet should be ~18 lbs. Adding extra sheets certainly doesn't seem like a good idea when trying to keep it on a diet.

KC: I think you're right, I'd need to do some kind of solid block between the axle and ply. I'm kind of thinking about using a hole saw in a 2x4 and making some wood cylinders that I would insert in the foam to bolt through between the ply and steel. Just use one size smaller hole saw (~1/8" smaller) when I get axle placement decided to put the hole in the foam, glue the wood cylinders in and use the pilot hole to place mounting holes in the inner 1/4" ply, place on frame and drill down from the inside to place holes in steel frame.

Trailer balance (tongue weight, tongue length relative to axle width) is more critical on a motorcycle, so I'm going to have to do quite a bit of measuring and weighing before I just go bolting stuff on.

[Off Grid Rving]

2x4 would not be a good choice for that, i'd glue up some wood that has wild grain in it so they don't split apart when bolting through them.

take some oak and quarter turn each layer and glue it up building up to the thickness you need then hole saw it and make your bolt blocks.

[bonnie]

I think you could do the bottom of the floor in foam and canvas like you plan. Just have hard block pads (good ply built up; or select solid oak or maple) where the foot print of the axle mounts and tongue tie in points will be; anti crush blocks if you will. You could even build a frame of 5/4 stock x 3 or 4 in an 'A'-frame shape, attach that to the underside of your deck then back fill with foam. That would give a nice solid tie in between the steel triangle and floor, without adding too much lumber.

I would worry that smaller flat plates just on the bottom would crush the foam over time, allowing the fasteners to get loose.

When you do get to the detailed measurements you will find that the torsion axle mounting points are actually in front of the axle center line; they have trailing arms that place the wheel centers behind the torsion pivot point.

What KC said. My current project has a torsion box floor and the bottom was covered with 6 oz fiberglass. The axle area was built up with 2x4s. The tongue was bolted on with angles and some plate. That area has cracked and split. Most likely from the foam compressing.

[rowerwet]

viewtopic.php?f=55&t=50313&hilit=motorcycle

[jae]

http://www.tnttt.com/viewtopic.php?f=55&t=50313&hilit=motorcycle

Perfect! I knew there had to be another build like what I want to do out there, just hadn't found it in a search yet. Now to read through and see how it turns out.