'Sleeper' for DC 1st gen tacoma

[woodslanding]

Well, someday I am planning to build a camper, and it will have a layout somewhere between this: https://pickup-camper-magazin.de/camp-crown-stealth-dc/ and the pro rig 2 as featured here. But the construction method will be CF or Fiberglass over foam, as pioneered by HomeSkillet. One thing I'm curious about with Home Skillet's CF technique is how it dealt with body flex. It doesn't seem like he considered that in his design at all, but I also haven't found any sign it gave him problems. If anybody knows, or can point me to a thread, that would be great. Still not decided on FG vs. CF... CF is pretty cheap these days, and less itchy. But I worry about it cracking when the frame/bed flexes. A combination might ultimately work best, with some FG on the corners to allow for some bendy-ness, and CF where it needs to be stiff...

In the meantime, as a warmup, I'm going to build a topper for my truck using that construction method (probably just FG). This is the truck:
.

It goes off road, it fits the kids, it's not huge, you can techincally put a camper on it. 118K miles! The only problem with this truck is that you can't sleep in the back. So I'm going to build a topper to allow me to sleep crosswise. Here's a rough mockup. The topper will stick out 6 inches on either side, a little less than the mirrors... That leaves room for a standard twin mattress, at 38x72. I'm well under 6-feet, so that will be fine for me. When I camp by myself, I can sleep in it, and when the whole family goes camping, my wife can have a cushy matress indoors...


First off, I bought an old topper for an S-10 for $100 on craigslist. Everything in good shape, including keys for the locks. Took all the windows out, and took the door off. It will need new struts, but I guess those are cheap on Amazon.

Home Despot was all out of 1" foamular, but I found a local source (WhiteCap) for actual styrofoam brand sheets in a soothing blue color. Bonus, they are 25 psi, instead of 15 for the pink. May be a tiny bit more sturdy that way.... My first cut was 4' long, and I didn't want to do it with the skilsaw, because the foam seemed fragile to support its weight. Now I'm thinking I could have made it work, but I decided to use the multi-tool against a metal straight edge. That worked okay, but I didn't get a very consistent 90 degrees with the cut. Luckily I started with one that had some margin. I'm going to be cutting a lot of this stuff, and the design is going to call for a lot of them to be angled by 22.5 degrees, so I rigged up a jig for the multi-tool:

Works pretty good, and I got the first sheet of foam mostly cut....

more soon.

 

[RonapRhys]

I wonder if a rotozip or other cutting bit on a router might work a bit better? Based on the jig you set up, I'm betting you could build something to work well with the router, which gives you a de facto fence, 90° and 22.5° cuts precisely.

 

[Beavervalley802]

Nice truck, i have an 04 doublecab. 270k miles and still doesnt burn a drop of oil, Just wish it got a full 6ft bed. Interested to see how this turns out!

By your drawing, it looks like all cuts will be straight, so why not tablesaw it? Easy to set angle and get nice clean straight cut.

 

[woodslanding]

Well, I've been going back and forth from the table saw to the multi tool. The tablesaw gives straighter cuts, but it kicks up a ton of styro-dust. The cuts with the multi-tool are surprisingly straight though. Got all the foam rough cut, and the plywood base built. More pics soon.

Not sure I get how to use a router for the 22.5 degree cuts. I do have a router table, so that might be something to look into. I'll research rotozip....

 

[woodslanding]

Okay, overdue for a post... but the kids were back home for a week in quarantine, so not much work done.

So I did do some cutting with the tablesaw, but I was worried about inhaling a bunch of plastic dust (and more important, my kids doing it!) Here's what the saw looks like after a cut:

Took forever to clean up. Luckily my daughter is very excited to use the shop-vac!

Briefly tried routing, but that was even worse!

I stepped the cutting up a bit by sharpening the side of a multitool blade on the grinder. That didn't kick up any dust, but kind of cut the foam by melting it in a not-very-clean way. Eventually I got the pieces rough cut. On the very left, you can see that 'frosted' edge I got with the un-serrated blade. Should hold glue well, at least!

Then, with the sidecut blade, I did the window openings, and did a test fit. Looks good.

The windows fit 3/4" wall, so I'll need to inset around the edges before I fiberglass. I bought a hot knife for that, I'll get to that next.

So finally, after some reading, I decided to make a hot wire cutter, and this is absolutely the only sane way to work with this stuff!

I've got it on this sliding bracket that's designed for drilling into pipe, so I can set up various angles. So I've been able to cut all the specialized angles where the pieces of foam meet.... The throat is small, which wouldn't work if I was cutting full sheets this way, but since everything is rough cut, it's no problem. I can set up various fences to do super clean cuts. I used an old 12v 3 amp power supply and 26 gauge nichrome wire. Using a special calculator, I came up with 24 inches for an appropriate length, so the wire runs down the back of the bench. If I need to surface plane or something like that, I can remount the wire horizontally.

Today, I did a test assembly, using wire nails pressed in by hand to check the fit. Came together fairly well. Toyed with raising the roof, and doing a small cabover, but decided to go with plan A. So I still need to put the roof on, and haven't beveled some of the affected front pieces. There's a gap around the front window piece, because I had to move the topper window down to match the truck window better. Should be easy to fill, I've got yards of thin strips of foam laying around!


So that's where I am now. Still trying to decide whether to use fiberglass or CF....

 

[Third]

That looks like styrene, is it?

In any event, always test a piece of the material with a dab of fiberglass resign.

Because any coating with a catalyst will dissolve styrene-like products (as will gasoline).

If it's styrene, then you will have to use an epoxy resign.

 

[woodslanding]

Absolutely using epoxy, yes! The very first example I ever found of this type of construction 5 or 6 years ago, he used polyester resin, and had to coat all of his foam with wood glue first, so it wouldn't melt... Don't need that extra step!

I ordered some PL300 special foam adhesive, but after looking at a few youtube videos comparing adhesives I guess I won't be using it. Most adhesives stay wet forever between two sheets of foam.... So I'm going to use the spray foam. It adheres like crazy, and will also fill in the gaps. Hoping the wire nails will hold things together against the expansion pressure. I'll probably put a ton of blue tape on also. To attach the foam to the plywood floor, I'll use gorilla glue.

Finished the beveled edges in front this morning, and now I'm trying to figure out what I want to do with the roof. My original plan was nearly flat (four triangles raised 1 inch in the center) but I want a bit more slope, and a bit more headroom in the center.

 

[woodslanding]

Okay, I think I am going to use fiberglass for the skin. A few reasons... It's half the price, to start with (not the price differential there used to be, though!) Since it's more resilient, it should survive being banged by tree limbs or hailed on a bit better. The chief advantage of CF (stiffness) won't matter without a cabover. The only real advantage to CF in this application would seem to be that the increased stiffness may prevent bubbling where excessive temperature causes the foam to off-gas. The typical solution for FG in that case is to paint it white so it doesn't get too hot. That seems to work okay, and reflecting the heat makes sense for other reasons. I guess if I used CF, I would probably be able to paint it a different color, but the jury's still out on that somewhat. Not a lot of examples out there. But Home Skillet's build was painted tan, and he didn't experience any bubbling, afaik.

It's not terribly difficult to repair those bubbles, but it would mess up your paint job....

I think I'm going to use 10 oz FG, single layer, two fill coats. Probably something thinner for the interior, maybe 6 oz. Suggestions welcome, I'm kind of guessing here...

 

[woodslanding]

Here's a rundown on the cutting methods. From top to bottom we have
1. original factory edge, pretty rough, but very straight!
2. cut with mounted multi-tool, rough and pretty dusty
3. table saw cut, smooth but very dusty
4. router cut, really hard to control, worst dust creation
5. hot wire cut, smoothest cut and zero dust. A little smoke though.

And here's some better views of the hot wire cutter setup. Lots of things I'll do differently next time, but this is working just fine:

can cut any angle from 0 to 40 degrees. If the arm was exactly an inch above the surface, I could get sharper cuts, but 40 is the largest angle I've needed so far.

 

[woodslanding]

Okay, quick update Rebuilt the hotwire cutter, since I'm in it for the long haul. Comes out with a couple of bolts, I can mark the angles for super quick adjustments, and I can use my fence on either side. I need to find a slightly less beefy power supply, but for now I just cut FAST. The wire gets red hot. I did preserve the scrapwood-and-drywall-screw ambiance of the original...
Next thing was to recess around the windows. By reversing the inner frame, I can make them work with a 3/4" thick wall (compared to the original molded which is around 3/16", I think.) The first tool I tried was this, which was utterly horrible:

Don't buy one of these to cut foam. The base gets too hot and the tip never gets hot enough.

Then I tried this:

Much better. With the curvy tip I got some pretty reasonable recesses:

Works great until it drags a hot glob of blue goo across the foam, then you get a blobby indentation. But easy enough to fill in later.

Now just a bunch of spackling and sanding. Want to do as much as possible to individual panels before I glue it all together. I imagine it will be more awkward then.


I've decided to do CF for the roof and front edges and the rest FG. I read that CF is actually more impact resistant than fiberglass, so that's the theory.... still trying to figure out what epoxy to use. U.S. composites is cheap, but expensive to ship... west systems and system 3 are all that I've found in town so far.

 

[woodslanding]

okay, I could use some advice.... I started sanding, and it's not going well.

I read in somewhere in the teardrop forums that the loctite PL300 foam glue was good glue for the Styro, because it sanded similarly, so your glue joints wouldn't end up proud. Well, I did not find that to be the case, although I was using it for a filler more than a glue. It is miserable to sand, and I ended up having to pull most of it off.

Then I read in a boat-building forum that the dap spackle was easy to sand against foam, which it is. But now I'm thinking it's going to give me adhesion issues--surely a fiberglass/dap bond is not going to hold for crap!?

So I'm thinking I should be using.... bondo? .... cabosil and epoxy mix? what is going to sand well against the foam, and still adhere to the fiberglass?

I imagine the dap will be fine in those thin cracks, but I need a sculpting solution for the window recesses. (BTW, I have smoothed/tapered the edges of the window surround, as I realized the fg is not going to track an edge like that well.)

Also, in watching the homeskillet videos, he skips over the part where he does the windows. I'm trying to figure out if I should cut the FG right at the window edge, or try to get it to fold around into the interior to cover some of the cutout edge.... if the latter, I guess I should probably also round the interior edge?

Any thoughts most welcome.
Thanks in advance!
-eric