Standing clam-shell mousetrip sleeper

[Bluebunny]

Hi Folks,
Not much apparent progress in the design stage of this standing clam-shell mousetrip sleeper. I am currently pondering how to handle the flexy 3-panel skins! For sure I'll need some temporary forms to set these monsters into space. I did learn that a single sheet of 16 feet long 1/4" ply is manageable, but getting three sheets of 16 footers by 4 feet wide to behave and line up their edges like good soldiers will be a challenge, to say the least!

Step one cutting will be straightforward, but step two stitching will be a challenge without some careful planning. No answers yet. I don't even want to face step 3 overhead epoxying of the seams ; with proper forms, I might roll things on their sides. I am beginning to see the merits of framing. The heartache savings may be worth the extra weight?? Maybe hybrid with partial frame...but I wander as I wonder....

Anyway, I have discovered a means of aiding flexy panel edge alignment using temporary copper wire as twist ties and temporary little wooden cheaters. Has helped with frameless panel alignment in preparation for gluing on a little boat-build project I am enjoying.

[OP827]

I never done this stitching thing, and yet volunteer here just to support your efforts. Logically thinking this method only works well when two plywood pieces are curved same curve on their edge when they can be stitched flat and then unfolded into a 3d shape. Having one piece straight edge and another curved will be more challenge to align and require more preparation, jigs etc. which may reduce the stitching technique advantages of simplicity. Sooo... if you want stiching, then the plywood pieces shapes should be made to work for that. OR you can glue or screw a strip of wood along one edge and then screw and glue another piece to the strip. Just a thought..

About ovehead epoxying.. .. in my build I plan to do epoxying either flat or upside down to have gravity on my side. After the whole roof is finished as a complete part, then I will turn it over and affix it to the lower part of the trailer.

[Bluebunny]

Thanks OP,
I believe you are right; I'll think about building the top upside down.With an easy mod, I now have a "flat spot" along the roof. I can put in a short series of wire stitches at the mid-section, then fold the sides upright and square it/attach it to forms. Then work my way along. This approach allows me to epoxy glue and fiberglass tape the seams with gravity as by friend - Gravity has won most of my battles with it...

The curves of the sides will do a lot to stiffen there at the rear. At the front, it curves on three sides of the dice, then the top flattens near the nose, allowing tip-up for the forward curves. It seems very doable with the proper forms. As I look at it upside down, it looks boat-like! I can do this! Thank you for your welcome advice.

Hey these monster panels are 14 feet long and 5-1/2 feet wide! Pushing the limit of the first T in TTT. The first T in my book is "dry weight under 900 pounds!" (I know, I know, FOAM!) I'll give my foam tribute to the outer top skin...

[OP827]

LOL, i lost *most* of my battles with gravity too, and glad I could help. I myself get a lot of help from guys at this forum all the time.

[GreenViking]

Good luck with that, I am sure you will learn alot at every turn... there will be language i'm sure!

Curious to see how you get the parts to mate without scratching and what types of tolerances and ability to seal the gaps when open. Wishing you lots of persistence, it is a necessary thing as the challenges stack for sure!

[Bluebunny]

Good luck with that, I am sure you will learn alot at every turn... there will be language i'm sure!

Curious to see how you get the parts to mate without scratching and what types of tolerances and ability to seal the gaps when open. Wishing you lots of persistence, it is a necessary thing as the challenges stack for sure!

the panels are of 1/4" plywood, so they're pretty scratch resistant. I'll be able to walk on them while on clean garage floor. Minor scuffs will cover with primer and paint. The ideal gap between plywood panels in stich-and-glue construction is "a gap", but if it gets wider than say 3/16", I will use a splinter of wood as a filler. If they touch, that is OK, too. Epoxy resin is a strong glue, and I always add multi-layers of "biaxial" fiberglass tape over the edges, joints, intersections etc.

Getting the panels to mate is not difficult using traditional drafting layout skills, whether with computer aid or paper. Each panel starts as a plane, and then can be predictably bent into a cylinder or cone shape. Geometry and trigonometry are the true tools required. (Oh, and the ability to cut straight - which would help me immensely).
Alternative to theory is to model; just get some tape and flat stock like card, paper, or (best) that thin wood stock used for laminating cabinets. Scale say an inch equals a foot, get some scissors, and do the classic old cut-and-try modeling. When you like it, lay the parts out flat, grid and measure them, prove your numbers by building another model from your grid numbers. If it were me developing from scratch; I'd model it a THIRD time...

[rowerwet]

I use tie wraps instead of wire to stitch my hulls together, I think it is easier, and you don't leave bloody finger prints when an end stabs you. I safety wire stuff all the time at work, I get enough holes there.

[Bluebunny]

Hi Folks,
Not much visible progress, but I actually have significantly upgraded the shell designs for improved:
1. weather and wind resistance;
2. non-interference and simpler tight-fit during the top lift;
3. simpler construction of the giant ply panels.

The biggest hurdle to date is wifey buy-in; maybe I buy the 5x8 red trailer this fall? Hope I don't have to live in it...

The image shows the improved structure. All in stitch-and-glue plywood construction with a 900lb dry-weight budget...

[Greg M]

Nice to see its still percolating.

[OP827]

It is looking very good! I am a little concerned about the back side panels, do you think they are not too large so potentially can be a little wobbly? I have similar streamlined design as you know and I have chosen to trim those as a triangle as you can see.

[Bluebunny]

Hi OP! Gunnels and gussets are two awesome words, they sound so nauty, but will get that job done:)

[Bluebunny]

Given the complexity of the shell for my clamshell sleeper, I've prudently decided to model it in 1/12 scale. Birch door skins are the exact scale for 1/4" plywood, so building the model should be straightforward. Shown in the photo is the model of the frame and deck, and those little rails I'm building into 1-1/2" scaled thick plies. We shall see if the rails will form the shell curves, and if I can get the tilting components to fit and actuate?

[OP827]

[Bluebunny]

When planning to build a new design, it is always a good idea to model it before building. In my case, showing only the model lower clamshell, I already found a length error on two panels! And of course the material came up short of expected. Only two hours to fix the model. Might have cost weeks and Hundreds of dollars had I gone straight to build.

The lower half (once properly cut) went together like a dream. I cannot wait to get to the big upper shell and try the fit!

[OP827]

Looks great! Cannot wait to see the finished model! My next build will start with first completely finished scaled model too. I learned my lesson now.
What do you plan for lift assist?