Hybrid Foamie Benroy Build

[TimC]

I'm going to have to go back to TD#1 and add the drip edge. I haven't noticed any problems with moisture lingering under the bottom corners, but, I hadn't really paid much attention before seeing the suggestion in that post. Thanks...

Tim

[TimC]

I'm still trying to figure out building methods on this foamie Benroy. I am cruising through George's build and realized that I may want to change my roof design a bit. I was originally going to do a lauan "inside-out" with wood spars and lauan roof. Seeing George's method for his front radius I was thinking that I would not be able to use 2" foam for the roof as the kerfs would show inside the cabin. Now I'm thinking "inside-out" with one layer of lauan for a ceiling and then finish with 2" foam. The lauan ceiling will hide the kerfs. I'm going to do some experimenting with the 2" kerfed to see what kind of inside-out rabbet I need to allow the 2" roof. I'm thinking the actual thickness at the radius may be different from flatter areas of foam. OR..., Can I fill any void with great stuff and carve a round over before I apply canvas? I've seen where folks fill gaps and carve/sand but I have no experience with that.

Tim

[TimC]

Committed... Had to get to Homely Depot before the Menards 11% rebate ended today so I could get a start on this thing.



I'll start a build journal when I find the right section to plant it in. I'm assuming the general Build Journal section is used for all the different types of builds.

Tim

[TimC]

Indeed George, this is fun, and addicting.

I'm learning how to do hot wire kerfing and cutting and hoping my theory of how to improve this particular wire (pictured below) is sound.

Here is my first attempt at kerfing to bend a foam panel. Notice the wide melt pattern at the "foot" of the kerf. The resulting bend is real good as shown in the last photo, I just think there is too much melt in the bottom of the kerf.


My wire has a 3/4" long "foot" that presents heat for an extended time in the kerf. I am thinking of modifying the wire so that the foot just turns back on itself immediately (sharpie drawing on the foam behind the actual wire). I hope that eliminates the extra time it is in the same spot melting away. I assume that because the two legs of the wire passing through quickly result in a thinner kerf on top. Am I making sense? The bottom of the kerf is not only wider than I expected, but it left less meat in that area than I hoped (1-1/2" foam and I was hoping to leave a 1/4 of the thickness or 3/8")

[TimC]

Again, thanks to George and GPW. They provided the inspiration to learn this hot wire method.

Some results of a new 12g copper wire design with a plywood guide.







A more uniform kerf (those left of the sharpie X). Width and depth are better and foam hinge thickness is more like I was shooting for.


The resulting bend required more force than the first trial with a similar radius. There was more popping noise when bending. This may mean more stress on the foam hinge. Good? Bad?

[GPW]

If you gently Heat the outside after kerfing , it bends easy ands stays there … 

[TimC]

8) If you gently Heat the outside after kerfing , it bends easy ands stays there … 

Good to know. I guess I'll have to look into a heat gun type unit.

Tim

[ghcoe]

Set it out in the sun for a bit. It should do the trick. Hot wire is a bit addictive. It makes such clean cuts when done right and no foam dust everywhere. Just make sure not to breath in the fumes though. Bad stuff. I use a fan to suck the fumes away.

[GPW]

Here’s the video on bending (un-kerfed) 1” foam with a cheap hobby heat gun .…. Try a piece of scrap … see what you think … ( OK, it’s boring , but informative )

https://www.youtube.com/watch?v=5WVKttqb6HQ

[TimC]

Thanks for the advice guys! I'm anxious to get started on this soon.