Requesting Plan critique

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Requesting Plan critique

Postby J.Squirrel » Mon Jul 03, 2017 12:29 pm

Hey there. This is my first build, and I would love some critique on my plan from the experts.
My goal for my first TD is to learn the skills to build my next ones properly, (and take it camping this summer, probably and ambitious goal). I'm focused on making something cheap and quick, with a life span of ~5 years.

So far I have a lot of progress into the design. I'm favoring an aerodynamic over a classic design especially in the rear. It's based closest to a new Cub design. I'm going for a foamie hybrid with a canvas paint shell. I have to wire up a HF 8'x4' trailer and its good to go. I already installed a tow hitch on my toyota camry. I have plastic piano wire hinges and two 20x24 cargo doors (I'm a small person and don't mind the squeeze, will probably upgrade later).

I'm planning to put foam between the walls, with luan 1/4 plywood shell it.

Image

Design questions:
1) For the wall upright braces in blue, will 2"x3/4" plywood suffice or maybe two layers of 3/4" plywood screwed and glued together. Or would it be better to have some 1"x1"/2"x2" pine braces? I have a bunch of spare 3/4 inch plywood that I would like to use up.

2) for Horizontal braces (in red) across the roof, is 3/4x3/4" pine sufficent? should I have a larger size?

3) will the rear flat walll complicate the hinge/seal process?

4) any other big pitfalls.

Cheers!
J. Squirrel
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Re: Requesting Plan critique

Postby mikeschn » Mon Jul 03, 2017 2:03 pm

I don't think you need that much wood in the walls...

Look how much I used... here: viewtopic.php?p=1136992#p1136992

Mike...
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Re: Requesting Plan critique

Postby tony.latham » Mon Jul 03, 2017 3:12 pm

I'd cut a 24" x 20" hole in a cardboard box and try crawling in and out. But maybe you've done that. Our doors are 26 x 36" and I know of folks with 32" doors that wish they'd gone with the bigger ones.

My eyes keep looking at your hatch with the nearly 90ยบ angle from a structural sense. :thinking:

You mention plastic piano hinge. I used the UV resistant stuff for my tongue box and after four years, it needs to be replaced.

Think ventilation too.... you'll need open windows on both sides and you'll regret not having some kind of fan.

Tony
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Re: Requesting Plan critique

Postby J.Squirrel » Mon Jul 03, 2017 3:24 pm

Mike,
Thanks! I defintely will reduce the number of vertical supports. Maybe just the door and back hatch. Probably went a little overboard on the horizontal support as well. Thanks for the link.
J
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Re: Requesting Plan critique

Postby J.Squirrel » Mon Jul 03, 2017 3:38 pm

Tony,
Thanks. I definitely plan to get a larger door next build.
On the piano hinge, I was thinking of covering that with some canvas to further seal it. I think that would protect it from the UV. It might also impede its bending. I'll have to test it out. I could also paint the hinge?
For ventilation. I plan to get a Maxxair box fan lid, and some of these vent holes: http://a.co/h3Vw6PC to place around the top.
J
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Re: Requesting Plan critique

Postby tony.latham » Mon Jul 03, 2017 6:42 pm

J.Squirrel wrote:Tony,
Thanks. I definitely plan to get a larger door next build.
On the piano hinge, I was thinking of covering that with some canvas to further seal it. I think that would protect it from the UV. It might also impede its bending. I'll have to test it out. I could also paint the hinge?
For ventilation. I plan to get a Maxxair box fan lid, and some of these vent holes: http://a.co/h3Vw6PC to place around the top.
J

My plastic hinge was supposed to be UV resistant. I think it is the flexing that is killing it.

If you put those vents up high, and the fan on top you'll get good air movement at the ceiling but not down where you are.

Without good ventilation, teardrops can get uncomfortable.

T
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Re: Requesting Plan critique

Postby rruff » Mon Jul 03, 2017 9:46 pm

mikeschn wrote:I don't think you need that much wood in the walls...
Look how much I used... here: viewtopic.php?p=1136992#p1136992
Mike...


Sorry for the segue, but a couple quick questions:
What did you use to glue the foam to wood?
What did you use to cut the foam?

My first attempt at clean cuts with a knife blade in a jigsaw did not come out well... :(
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Re: Requesting Plan critique

Postby J.Squirrel » Mon Jul 03, 2017 11:03 pm

Some more designing:
With 4 Vents and a fan. Took out some wall frames and spars.
Image
Thanks for all the suggestions so far :thumbsup:
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Re: Requesting Plan critique

Postby J.Squirrel » Mon Jul 03, 2017 11:28 pm

rruff wrote: Sorry for the segue, but a couple quick questions:

Hey, I actually haven't started cutting yet, I'm still in the planning stage. But I have been looking around for some tutorials. One of the best I've found is by rowerwet viewtopic.php?f=55&t=56186. looks like he uses Loctite PL Premium .
Also on cutting the foam. viewtopic.php?t=40958&p=751880
Good luck, I'll post what I end up doing. I like the sound of the hot knife with a soldering gun.
J
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Re: Requesting Plan critique

Postby ghcoe » Tue Jul 04, 2017 7:48 am

You might read through my build. I did not use any wood except for the floor. Everything else is foam and metal flashing or beading for hard points if you need them. I also use the hot wire method for cutting the foam. Might check out my working with flashing and beading and hot wire threads too. Links are in the signature.
George.

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My build viewtopic.php?t=54099
Working with flashing for foamie construction viewtopic.php?f=55&t=60303
Making a hot wire http://tnttt.com/viewtopic.php?f=55&t=55323
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Re: Requesting Plan critique

Postby ghcoe » Tue Jul 04, 2017 7:54 am

Oh, forgot to mention that I used canvas over my galley hinge. Works great.
George.

Gorrilla Glue, Great Stuff and Gripper. The three G's of foamie construction.

My build viewtopic.php?t=54099
Working with flashing for foamie construction viewtopic.php?f=55&t=60303
Making a hot wire http://tnttt.com/viewtopic.php?f=55&t=55323
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Re: Requesting Plan critique

Postby rruff » Tue Jul 04, 2017 9:19 am

J.Squirrel wrote:
rruff wrote: Sorry for the segue, but a couple quick questions:

Hey, I actually haven't started cutting yet, I'm still in the planning stage. But I have been looking around for some tutorials. One of the best I've found is by rowerwet viewtopic.php?f=55&t=56186. looks like he uses Loctite PL Premium . Also on cutting the foam. viewtopic.php?t=40958&p=751880
Good luck, I'll post what I end up doing. I like the sound of the hot knife with a soldering gun.
J


Thanks for that! It does look interesting, but I don't understand what NathanL is saying. Do you?:

"Homemade hot knife, took an electric soldering iron (the pistol grip kind) and cut length piece of coat hanger and made a loop out and back into the other deal.

Cuts like a hot knife thru butter and leaves a perfectly clean edge. Can also be used to follow a template as well. When you are done you take the loop of coat hanger wire out (use uncoated or clean it real well to get the laquer off the new kind) and put your soldering iron attachement back in."

The problem I had with the jigsaw was it wanted to jump around, and the blade would bend if I changed directions. I tried to cut the foam freehand though, without a guide (2" foam). I was no better with a long utility knife. So my foam did not fit the openings in the wood frame very well. A little trimming fixed the tight spots, but then I still had to deal with some significant gaps. I did epoxy fiberglass for the skins, so I needed a good surface with no gaps or cracks at all. I ended up using a combination of spray foam and epoxy paste, but it was a PITA to get it right.

Obviously this will be much less critical for you since you are using plywood skins. But I wouldn't recommend plywood skins, unless you fiberglass over them.

My critique of your plan involves this statement: "My goal for my first TD is to learn the skills to build my next ones properly, (and take it camping this summer, probably and ambitious goal). I'm focused on making something cheap and quick, with a life span of ~5 years."

You can make it cheap and quick, but if you don't use the methods and materials you feel are best, will you really learn how to do the next ones? I would at least use the materials and methods that look optimal to you. Much of the time in any of these builds is spent on details and making it pretty. You can more readily cut corners there. That's what I'm doing anyway. :beer: It won't be pretty, but it will be light and strong and last 20 years. I hope! :NC At least I'll have the epoxy/fiberglass/foam experience for the nest one if it breaks.
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