Step 1: Get a Trailer
Step 2: Build a Frame
I also wanted it to be wide enough to fit a queen 57"x 77" x6" matress, but the trailer is 48" so I built the frame a bit wider...
Two sides 2x4x73
Front and rear 2x4x57
Interior crossbraces 2x4x54 and 2x2x54
Lengthwise 2x2's added because of the wheelwell cutouts.
Step 3: Attach to Frame
Going to use lag bolts and/or u bolts to hold in place depending in the trailer we are using (have a catamaran sailboat trailer that this could fit on when camp-sailing)
Step 4: Cut Out Walls
Here was exact one I used to model mine
Drew the ellipses using string and sharpie
Front and rear corners are Circle radius 30"
Front roof curve is small ellipse using two focal points the front of which uses same center as circle and the back one 30" from the rear edge. Adjust length as required to get height desired.
Rear roof curve used rear focal point and another beyond the front wall to get a more gradually sloping line.
Rear lower is also 30" radius circle
(See drawing pictures added)
Then began cutting
long razor/box cutter
Optional tools: hot knife (foam carving specialty tool) $30 or soEDIT***GET THE HOT KNIFE!!!
EDIT*** the best way to cut foam is to get a hot knife- details later*** ...previous comments: The best way to carve is heat up knife with torch and cut a few inches at a time. Takes a while but works well. Clean off the blade whichever way you please... (Xps- extruded polystyrene- will melt onto blade then won't cut as well if covered)
More details on ellipse drawing will be added to this step later.
Step 5: Glue Up the Walls
Use gloves- almost impossible to get off hands!EDIT***IT IS COMPLETELY IMPOSSIBLE TO GET OFF YOUR HANDS- tried goo gone with dawn and lighter fluid at the same time and no luck***
I first notched out the top supports that will hold the roof vent. Spaced 14.5" *between* so 16" from beginning of one to the next, I spaced the rear spars 18" because the curve is more gradual needing less shaping support
I used 2x2's for the cross pieces
-ended up 61" in length for a frame that was 57" plus 2" XPS board on each side
I lightly sanded the foam and applied glue to wooden frame
Sandwiched the two together between clamps via 1x4 or screws as pictured
Check bottle for cure times to be exact I'm leaving it overnight as I did with the frame
EDIT ***so we ran out of clamps do screwed a 1x4 up against the side using 4" screws. Left too long and screws glued themselves intro the frame by passing through the glue layer on the foam. DONT DO THAT! Just plan to take the screws out after a few hours, maybe 3 or 4.
Step 6: Glue in Cross Supports
He poured in the glue first and I set in the 2x2
Then from both sides we cleaned up the excess glue and duct taped over to prevent spilling... Didn't work to well in places but no bad altogether.
Going to let it sit overnight and maybe add more where necessary tomorrow ***while wearing gloves***
Step 7: Get the Roof Curving Prepped
Obviously the foam would most likely snap on the tight curves, so I have to make a few cuts to get it ready for the bend.
Tool Options include skil saw, hot foam knife, razor blades/xacto knife, and of course the torch and knife (which I used)EDIT***this would be best for the 30 watt cutting tool. I used the torch and razor which worked better than the HF HOt Knife.
Here is a nice write up of exactly how to breakdown what is necessary to "kurf" the foam.
I decided to just try it out and see what worked (or didn't) by trying some various depths at distances between.
The best for the hot razor blade was every 2" .75" deep into the 1" foam. (The hot knife added later worked well at 1" intervals .5" deep. Any deeper and the foam would crack.
At first I used my sauter pen (3rd pic) and melted through like a hot-knife would. I did cuts every 4" ending up with a nice curve but snapped a couple pieces on the opposite side of the bend. I WOULD SUGGEST AGAINST A SAUTER TIP! It will just destroy your foam (unless you can change out the tip with some sort of blade or wire)
Instead, I went back to my dewalt razor-knife and harbor freight torch and cut groves 3/4" deep every 2" for the sharper curves at front and rear then 4" for the gradual bend on top as shown in 5th picture
I'll add a video link when I log on to computer!
Note: an option for making the trunk lid(which I am not due to cost of hurricane hinge and lacking overall length,) would be to get an exact kurf measurement and glue the cuts closed for a hardened, self-shaping hood. (This is shown in the link above.)
Another note: I have a skil saw that would have saved me a ton of time heating up that darn blade time and time again, but it was late out tonight so I had to keep it quiet and had ZERO desire to vacuum up pink foamdust tomorrow!
I might add some glue in cracks once it is mounted to framing. To add rigidity as reduce heat loss/gain.
Step 8: Extra Framing
I opted for a 26"x 32" door. Used 30&3/4" tall with 16" wide cross piece of 1x2" ripped from the 1x4"s I used for the door frame which measured 27 & 3/4" wide with 32" tall.
Also had to make a frame for the ceiling vent (with 12v fan) 16.5" across with 14" opening. Used 1x2's laid on side for the frame, lifting the vent up 5/8." I cut a 14.5" hole to allow the vent room to drop in. Using butyl tape between frame and vent. Gluing frame to the XPS shell before fiberglassing.
*note* predrill and counter-sink the skinny 1x2"s. They can split easily if over-pressured. Also, I glued every piece of framing for more stability and rigidity. I also finally broke down and got the HOT KNIFE from harbor freight. It is amazing. I wish I would have also picked up the 30 watt hot multitool as well. The hot knife was a bit too big for curfing.
Dimensions and work for windows yet to come.
Step 9: Begin Adding the Skin
Only cover half before moving on to next step. You will need it to be open to fit larger pieces in and access framing with drill.
It really is a good idea to do the roof at two separate times, this is one if the highest tension areas because of the bend so the glue will need a bit longer to get set up before unclamping. After I finished one piece of the roof I worked on other areas while the glue dried.
Step 10: Shelf and Floor
Adding floating hardwood later!
Also I cut some small holes (using the hot knife!) in the walls through which to slide additional 61" 2x2"s crossbeams for a shelf frame. (Pictured) I used three crosspieces in total two for the base (around 21" high from floor- clearance for my size 12's on a 6" air bed) and one vertical crossbeam 18" higher to use to build a storage cubby/shelf front wall.
Once I finished shelf framing I finished putting on the shell pieces. Going to use the extra floating hardwood for the shelf. Considered glassing in some leftover 1 inch XPS foam but ran out messing up and trial and error curves.
Step 11: Finish Attaching Roof
Step 12: Begin Fairing the Shell and Doors
My girlfriend followed me with a trowel cleaning up the extra cuz who knows the rate that stuff comes out. MESS
After about 30-45 mins I grabbed the little razor to carve off excess and begin shaping the shell. The foam roof piece overhung the walls by an inch or so on either side so I had to trim off the extra to give the sides a smooth profile
Also did the door trim.
Step 13: Finishing the Doors
The frame needed to be 19 3/4 wide by 23 3/4 tall for the window.
Also I painted the window krylon hammered to go with the color scheme a bit. I taped off the rubber parts and the glass of course. Hopefully finish the window up tomorrow.
I did my first layer of fiberglass on the other door today.
I faired the foam door with spray foam first. (Pictured) sanded it to get it relatively flat before glassing.
I bought a glue roller and put a layer down first, laid a layer of glass over the frame and put one more layer of glue to coat/soak the fiberglass cloth. There was about 3/4" overhang on all sides extra that I'll trim when the glue dries tonight.