Wolfgang's 2&2 built updated December 25, 2010

[Ageless]

*perk*

Do I see a contour side-to-side in those spars?

I've been tossing that about in my mind . . .if thin ply could be contoured in two directions . .. now I'll find out

[Juneaudave]

Wow!!!!

[Wolfgang92025]

*perk*

Do I see a contour side-to-side in those spars?

I've been tossing that about in my mind . . .if thin ply could be contoured in two directions . .. now I'll find out

ageless,

Sorry, but I don't understand your question.
I did build an arch into the spar. I built a camper shell years ago and over the years the spars started to sag in the middle. Didn't want to do that again.

Wolfgang

[Ageless]

It looks like there is a curvature in the spars which leads me to believe that the plywood skin will need to flex in two directions; along the curve of the sidewalls and at 90 degrees along the spars

[Wolfgang92025]

ageless,

You are right. My spars measure about 64". The spar has about 1 1/2" bow in it. The roof is 1/8" thick. I may not be able to use a full 4' wide sheet. Hope to know the answer in about a week.

Wolfgang

[Ageless]

BTW; love the finish on the sidewall!!

[angib]

It looks like there is a curvature in the spars which leads me to believe that the plywood skin will need to flex in two directions; along the curve of the sidewalls and at 90 degrees along the spars

I agree - my gut feel is that it will be impossible to get the roof panels to bend smoothly like this, but maybe the side-to-side curvature is just small enough for the ply to be bent smoothly into place. In boatbuilding it is called 'tortured ply' construction and requires some fairly large forces to ge the ply to fit.

I think it would be worth doing a trail fit of the roof panels as soon as possible to see if you can force the ply into place without wrinkling along the outer edges. If it can't fit, it would be better to find out sooner rather than later.

Andrew

[Wolfgang92025]

Andrew and Ageless,

Great feedback. I was only thinking in a single plane when I came up with this design. I will play with it this week.
I did check last night on the bow, it's about 0.5" on the inside and about 1.0" on the outside of the rib.

wish me luck.

Wolfgang

[angib]

It would be worth a test as simple as fitting one piece of ply in place and trying to hold it down with duct tape - if that isn't strong enough to get it to lie down smoothly, then nails/screws/glue won't either.

The downside is the duct tape glue residue and what damage might be done removing the duct tape!

Curvature in two directions at once like this is theoretically impossible (though either curvature on its own is easy) - the only question is whether the transverse curvature is so slight that the theory fails to notice that you're breaking the rules and lets you get away with it.....

Andrew

[john]

I wanted to avoid a flat roof so I cut the tops of my spars with a bow. I left the bottom flat for interior skinning ease.

The spars are 3/4" higher in the middle than on the ends near the sides of the trailer.

As they approach the front and rear curves (in profile) they flatten so as to avoid a double curve. Still, I had to go from curved to flat spars over 2' with a single piece of ply. I had no problems with this and feel that I could have raised the centers of the spars a little higher with no difficulty.

Again, I did not have a compound curve to skin but, in a sense, I was half way there.

[bohemian]

Wolfgang I was looking to see if anyone was building the 2x2 and I came across your post. Your trailer is simply awesome. And I see your a master craftsmen to boot. I thought of doing the 2x2 the same way as my first teardrop. I also agree with you on having fenders. It just looks cool that way. I look forward to seeing more of your build. -Wayne

[starleen2]

Applying plywood to a compound curve can be done in strips. I tried to do the curvature with one piece and it failed miserably. - plywood just wouldn't stretch in two directions! However, I did get it done by planing each span. it require several test fits to get the edges to match as closely as possible.

Sanding on the sides – the vertical strips are fiberglassesd seams. The front radius has a strip of fiberglass to seal the edges


Front fillets and seams

[Wolfgang92025]

So..............
After Andrew and Ageless pointed out the trouble spot in my design, I spend a few night just looking at it and thinking about possible fixes.

Showing a close up of the bow I built in the spar. About an inch in bow.



I was going the cut of the old truss close to the wall and install new straight spars.
Was not real thrilled with that prospect.
About mid night the third day the solution hit me while laying in bed.
Actually got up and went into the garage to see if it would work?



I cut the 1/2" x 1' in the middle and removed to 1/4" dowel.



I glued the two 1/2" x 1" pieces together and added a third one to straighten the center portion.



So now the spar has maybe an 1/4" bow.
Should work OK.


Thanks to all for input to possible solution.
Ceiling is next.

Wolfgang

[Wolfgang92025]

Making progress.............
Got the ceiling pieces varnished and all but one are now part of the trailer.
I left the front ceiling piece off so I could load the big pieces through the front instead of trying to make everything fit through the door.

Interior shot of the back of the tear
Closet on the right, porta potty in the center and storage on the left.


The closet frame is complete (pocket screws are a wonderful thing), but still needs varnish and is sitting in place.
Started working on the fender well covers.
Cut the oak trim to go between the panels to hide the gap.
Fantastic fan should be here by the weekend.
OHHHH......., I see more varnish in my near future.

Wolfgang

[Wolfgang92025]

Got some more goodies last week

Brake and running lights


Fantastic fan just sitting in place


Fantastic fan interior shot


Worked some more on the interior cabinets.
Interior rear cabinet varnished and glued/screwed in place.


Coated inside wheel well


And started working on the front cabinet framing which will also hide the AC.



Wolfgang