Design Review

[dglenn1960]

Ok, quick design review (boy, it's post-away day for me).

Trailer goals: lightweight, towable by motorcycle. Sleeps 2, real cozy like. Decent ventilation, small storage inside, shore power ac only.

Design:
- Overall body dimensions: 40" wide, 39" tall, 6'2" long
- HF 800lb trailer, 8" wheels (~130 empty) (bought)
- lengthened tongue (2.5x2.5 1/8 square tubing, 6') (bought)
- 1/2" ply floor (likely birch underlayment)
- 2" x 3/4" oak frame inside (serves as nailer and extra strength for body which will extend over frame about 1' fore/aft)
- 1/2" ply sides (likely birch underlayment)
- 3/4" x 1" spars (might reduce to 3/4 x 3/4)
- 1/4" luan (or possibly 5/16" poly-therm) for roof
- homemade lexan awning windows
- internal storage shelf (face frame with 1/4 luan slide doors)
- all LED lights (tail, red/amber side markers, 3rd brake) (bought)
- leaving sufficient spar space for ceiling vent or fan

I have contemplated using 1/4" sides with bandsawn nailers around top edges (for nailers). Thinking that 1/2 ply would be quicker and might be about same weight. Mike's ultralight laminated frame is very enticing, just don't want to take the time for this build.

For the top all I can find in my area (Menards, Lowe's, and Home Depot no less) is Poly-Therm Lite. While similar to Coroplast (which I would rather use) it is a bit heavier (and costlier). It is UV protected, though only rated for indoor use. Definitely qualifies as experimental.

I have also contemplated no HF trailer underneath, but build speed wins out here (using HF is certainly easier). And I harbor some fear of catastrohpic failure when pulling with motorcycle, having a 'real' steel trailer underneath seems safer somehow.

<img src="http://www.glennweb.net/home/images/tear_ply_1.jpg">

<img src="http://www.glennweb.net/home/images/tear_ply_2.jpg">

<img src="http://www.glennweb.net/home/images/tear_ply_3.jpg">

~dave

[Miriam C.]

Dave,
Looks good to me. Why is the Poly-therm lite indoor only rated and if so, why does it have a UV rating?

Miriam

[mikeschn]

Could you make the top of the window a little curved, and raise it up a little? Since it's homemade, you could!!!

Just use a shorter piano hinge!

Mike...

[dglenn1960]

Well the poly-therm site says that the UV treatment is to keep it from yellowing from indirect sun (it's marketed for wet wall interior construction). It's all plastic so unless the glue is the problem I don't see why it wouldn't work in an exterior application. The core orientation let's it bend easily (core cells run across the 4x8 sheet) so it would seem to be a pretty good lightweight choice for my application. Would probably just wrap it, screw it at the edges and 2 places in the middle (of the spars) with an exterior washer. Since I've yet to find a local 1/8 luan supply this was the next best thing.

~dave

[Miriam C.]

Dave
Are you going to cover this with something? I am not sure how you are going to keep the water out if you use screws. Silicone might shrink away or not stick. If this is the same composition as coroplast you might check out the 3M tape Sid used. Someone also used Henry's glue on coroplast with good results. Maybe you could fill the holes with it. 3M tape sticks instantly and the Henry's gave more time to work with it.

Good luck
Miriam

[asianflava]

The window looks kinda big. I wouldn't want to lean up against it on a cold night.

[Ira]

Dave, any particular reason you have the door opening that way?

While a suicide mounted door may not be the end of the world when towing with a car, you wouldn't want it to fly open when towing with a motorcycle.

[dglenn1960]

Remember, this tear is on a pretty small scale, so the doors and openings look big. The windows are 'only' 18x18, not all that large (most I've been shopping for are in the 19x24 range). Got ta have some air when I'm sleepin'.

The doors open normally (to the rear, no suicide). Agree on this one, suicide are cool but not practical. Most likely they look like the might open the other way because of their shape. Again, it's a small tear and the door opening is only ~ 24w x 34h. But the 34h is at the highest point and is heavily rounded. I need about ~30 sitting down to not whack my head getting out.

I wasn't planning on covering the the poly-therm (it has a nice white, thick, layer on the outside, probably > 12mil) and seems quit durable. Good point on the sealing though. I was considering silicone in/under each screw, but that might not be enough. Glue might be the better option here, I could always try the poly glue and see how it holds up (screws could be added later if necessary).

Here's a picture with the sketchup 6' man standing right next to the tear for scale and one with the motorcycle to scale. It's small, really...

<img src="http://www.glennweb.net/home/images/tear_ply_5.jpg">

<img src="http://www.glennweb.net/home/images/tear_ply_6.jpg">

[Miriam C.]

Dave
I am not sure poly will stick to that. If you have not already done so I would suggest you read the Farmex thread. It has the glue (henrys 663 I think) and the tape that Sid used is from 3M and is listed in the following thread.

http://www.tnttt.com/viewtopic.php?t=6803&postdays=0&postorder=asc&start=90

If I put screw holes in the top I think I would use the Henry's. Sid also had a plywood base under his coroplast and used special tape. (listed in the post). I know the corrigated stuff is ridgid but I wonder if it will handle the wind forces and not tear away with screws and nothing else.

Where is Andrew?
I feel like a serious party pooper I thought this was his job. Isn't he the one who is suppose to shoot down good ideas.

Miriam---doom and gloomster

[Ira]

Dave, that's gonna be really cool.

AND TAKE YOUR TIME ON THOSE EXTERIOR SKINS!

There are probably some great ideas you can come up with to match the style and lines of your bike.

Two other things:

What are your plans for the interior ceiling? It's my understanding that you HAVE to have one, because it really sterngthens up the entire structure.

Next, you are REALLY gonna laugh, or cry, at how much actual storage space you get out of that cabinet. You may just want to kill it to give yourself more room in there, and go with some under-floor storage if you think you really need it.

[dglenn1960]

Ah, the doom and gloom parade.

Installation info on the site indicates that they make plastic rivets (16 on center) to attached the panels. They also glue with polyurethane adhesive, so that seems normal.

http://www.parklandplastics.com/durotherm.shtml

The thing that is bugging me most is the expansion (1/4 total across 4' sheet). They recommend allowing 1/8 on each side, though they also glue the field of the panel down (presumably the glue expands with the panel).

I would also need to use one of their recommended moldings for the one joint I would need along the top (takes ~ 1.5 sheets to cover top). For wall installations they recommend their molding and pump it full of a silicone sealant before attaching.

Like I said, certainly experimental...

~dave

[Ira]

Hey--it's not a doom and gloom parade. A lot of us are PSYCHED to see you make this happen!

There's nothing cooler than a TD being towed by a motorcycle. It's good for all of us who are into this.

But since you're playing guinea pig, we HAVE to stick our 2 cents in, whether what we're saying is 100% correct or not. We DON'T want this to fail.

We're ALL rooting for you!

(But I'm telling you, aside from sticking a tiny TV in there, that cabinet is going to be worthless.)

[angib]

Dave,

It does indeed sound interesting. A few thoughts:

- The web site only lists a 15/32" thickness - will this really bend round a teardrop shape without kinking the inner skin? Cancel that - I've just looked at the spec and it lists the Lite version at 5/16" - perfect.

- I get kinda nervous when they say "will not yellow from reflected sunlight" - sounds like undercover storage will be required.

- I'd forget about their expansion allowance - you're only installing 1 1/2 panels and you can't allow any expansion relative to the woodwork underneath, or else your water seal is broken - so I'd say stick and screw it down all over and use their adhesive in the joining moulding.

- The quoted heat deflection temperature of 79C/174F sounds good.

- I can't find the density - except on the MSDS which gives 0,4-2,0 - how can it vary like that? Presumably you've picked up a sheet and know what it weighs.

I'll be interested to see how the experiment works out.

Andrew
(currently on holiday from doomsaying - I couldn't keep up the requisite scowl)

[Miriam C.]

Dave, the truth is a lot of us really want this to be really good so we can copy, copy, copy...

Enjoy
Miriam
No more gloom and doom.

[dglenn1960]

Sorry, that was supposed to be the winky face on the doom/gloom... I don't mind the crititique (I asked for it). When we design/build these things in a vacuum getting input from others is extra valuable, which is what makes a forum like this so useful. Please, keep it up.

As for durotherm, I don't like the questionable yellowing possibility. From the stack in the store I can see that some are bright white, and some aren't (a bit yellowish). So only time will tell how it ages outside.

I did have another closer look at it. It weighs about the same as a sheet of luan (haven't used a scale, just by feel) so it isn't better that way. The outside covering is much thicker than the inner (should help greatly when bending. It does have a tendency to bend much like cardboard (where it tends to fail at one corrogation more than others). I was also concerned about it not being 'honeycombed' throughout (the look is much like cardboard, with the tubular corrogations across the width). However the tubes are not fully open across the width, they are closed every ~1/4 or so.

I'm not totally convinced using the durotherm is a grand idea, and I may try to bend the available 1/4 luan around the tear first (cost is low and it could work fine).

The ceiling at this point will be uncovered. What I give up in strength I get back in weight, which is my main concern. And for storage I am following in the path of Bob Harkema and will store gear in containers bungeed inside the tear, and can place them underneath when sleeping. This will also give me more flexibility when loading the trailer (and hitch weight) which is incredibly important when towing with a bike.

~dave