Sides, stringers and bulkheads

[McTeardrops]

Big day in the shop today. Got the aluminum angle below the hatch rough- formed and sized, sides up, all the stringers and bulkheads installed.

Ira take note: Wondered why I was having so much trouble beating the Home Depot 3/4 inch angle into shape, then I measured next to the tag that said 3/4 by 3/4, and found it was actually one inch!

[SteveH]

Lookin' good, Lenny.

[IraRat]

Yeah! It's really coming along!

And that's one of those things that keeps driving me crazy--true dimensions versus rough dimensions.

When I hear someone say a "2 by 4," I know it's not 2 by 4! (And I always need clarification of the true dimension.) As far as your aluminum goes, that makes no sense to me. It should measure what it SAYS.

Also, what kind of wood are you using for your spars? Gotta make a decision by TOMORROW.

[SteveH]

Also, what kind of wood are you using for your spars?

Don't know, but that looks like 2 X 3 (ripped 2 X 6) to me.

[McTeardrops]

Ira

My stringers are generic Home Depot pine. Found a straight 2 x 12 with nice grain and some heft to it, ripped to 1 1/2". Hinge spar is laminated oak, 3" x 1 1/2". Attached with #8 x 1 1/2" square drive pocket hole screws from McFeely's, and PL glue.

[IraRat]

Ira

My stringers are generic Home Depot pine. Found a straight 2 x 12 with nice grain and some heft to it, ripped to 1 1/2". Hinge spar is laminated oak, 3" x 1 1/2". Attached with #8 x 1 1/2" square drive pocket hole screws from McFeely's, and PL glue.

Okay, so you ARE using pine for your spars. I'm gonna use two 3/4 by 1 1/2 for each, glued together, for a spar of 1 1/2 square. (I can't rip.)

I'll use poplar or white oak for the hinge spar, but I dont think my HD had white oak. Only red, which I've heard isn't as good. And yep, that was the dimension I was thinking of for the hinge spar--3 by 1 1/2.

I'm a little confused about the small square ply piece you placed in the bottom front. Are you using ply for the exterior roof?

[McTeardrops]

Ira

The piece you mention is 3/4 ply, 14" tall, fitting in a dado in the lowest stringer. I added this bulkhead since the under cabinet bulkhead is not fixed, to allow installation/removal of full-size mattress, and to gain two inches of headroom. Sandwich ceiling will start from a batten on top of the stringer. Sidewalls are 3/4' plywood, ceiling is pickled 1/8" Baltic Birch, skin is 3/16 masonite under .060 aluminum.


The masked piece is surplus oak, temporary, used to hold up the front of the side. The notched ply is a "third hand", clamped to the side to hold the stringer in position during pockethole screw insertion. The screws have a tendency to "kick" the piece as they grab, otherwise.

[IraRat]

.060 aluminum? That's pretty thick, isn't it?

I ask because my current plan is to do my roof in brass-colored aluminum (the sides are woody), but I planned on using .032 right on top of the spars--not on any wood or masonite.

I'M SO CONFUSED!!!

[Chris C]

IraRat, you'll need some sort of substrate onto which to glue the aluminum...............and if you choose not to provide that then you'd better go with some pretty thick sheeting. A tear gains it's strenght from being a totally enclosed structure..............enclosed in plywood. .032" aluminum would provide no structural strength at all, I wouldn't think. Oh, the spars would help, but are mainly there to hold the sides together while you apply a skin on the inside and outside. I think most plans probably cover that subject quite clearly.

[IraRat]

IraRat, you'll need some sort of substrate onto which to glue the aluminum

So do I get labeled a Kuffel basher again when I say that the Cubby plans call for .032 and no substrate?

[toypusher]

IraRat, you'll need some sort of substrate onto which to glue the aluminum

So do I get labeled a Kuffel basher again when I say that the Cubby plans call for .032 and no substrate?

Chris may not understand that the plans call for the spaces between the inner roof skin and the .032 aluminum is going to be filled with rigid insulation. It will not be 'just' the aluminum on the roof.

Kerry

[Chris C]

IraRat, I don't know much about any of the specific plans out there, so I don't know much about bashing of any kind. If your plans call for no substrate, build it that way. It was just my opinion. But Kerry was correct, I didn't realize you were going to install an interior skin. That, of course, would help stiffen the structure. Still..........I don't know that I'd want to build without plywood on the top. I'm from Oklahoma.............you know, where we have lots of hail storms. Skinned like that in Oklahoma would be a guarantee of dimples in the Spring.

[rjhager]

Hi, Chris,
I'm with you on the substrate. I'm using Kuffelcreek plans for my Comet and, just like Ira says, Kevin uses polyurethane glue to attach the aluminum directly to the spars. Hail was my first consideration since my trailer will have to live outside a garage so I'm going with 1/8" luan glued and screwed to the spars and then I'll attach the aluminum. I'm hoping that extra 1/8" won't cause me to be out of the limits of my 4'-wide aluminum!

Randy

[TomS]

I'm using 3/8 flexible luan (aka "Wacky Wood") for the outer skin on my Cubby's roof. The inside will be skined with 1/8 ply. Between those two layers I'll have 1 1/4" of rigid foam insulation. I'm ging to seal the exterior with fiberglass or epoxy paint. I haven't decided yet.

The Cubby plans also call for 3/4 x 1 1/4 inch spars. The spars are doubled up where the cabinets meet the roof. Since, I'm building 5-feet wide, I decided this was not enough support for the roof. In addition to the longer span, mine will support snow loads in the winter months. Accordingly, I doubled up all my spars.

I believe Kevin Hauser (dba Kuffel Creek) was trying to keep the weight down when he designed the roof with just the aluminum skin and no substrate beneath it. Kevin lives in Southern California where it rarely rains and never snows.

[IraRat]

I'm gonna cross this bridge when I come to it. A substrate makes perfect sense for a million reasons, not the least of which being I would think you would get the perfect curve on your skin, no bulges from spars that may be a little off.

My problem is definitely weight, because although Kevin says that my Cubby will come in way under top capacity for the light HF trailer I'm using, I'm cheating and "overbuilding" in other areas that don't follow the plans. Like also doubling up on the spars, as Tom is doing.

I'm hoping that once the interior roof and side skins are on, I'll have decided whether to go full woody, or use a brass-colored aluminum after all. Forunately, nothing in my build plans are critical right now to have to make this decision immediately.