FoamStream...

[mezmo]

Hi GPW,

If you are not yet finished kerfing...

Since you had such good luck [skill too, I'm sure] hotwire cutting
the foam planks from the larger foam billets, maybe you could do
a version of this linked technique with a hot wire cutter on your
already cut planks. Just bead and cove your planks. Maybe a slight
grooving at the rib interval across the planks too, if you'd want them
to be snug around the ribs and not have to worry about a smooth
curve inside to fit on/over them.

http://www.epoxyworks.com/34/index.html
Issue 34, Spring 2012
Article: Foam Strip Plank Boatbuilding by John Lindahl

The boatbuilding bead and cove method, done at the larger scale
of your plank thickness could be a way out of your predicament.
The method would also be self-aligning as you join them together,
I would guess laying the beaded and coved planks cove-up would
probably be the best way to lay them up.

Just an alternative to consider...

Cheers,
Norm/mezmo

[GPW]

Well, as you know I put a lot of thought into this trailer ... going for a “look” ... As originally planned , the Blu and Pink foams would have been (IMHO) a little easier to use ...but because I’m was always concerned with Thrifty (retired) the beaded foam presented itself at a good price so I went in that direction , and yes, beaded foam is different to work with ... a little more brittle in the breaking dept. ... a problem with the big kerfs . The smaller closely spaced kerfs seem to do better with this material ... I think the saw blade trick will help , but there’s still a lot of kerfing to do ... The nice thing is the little kerfs do look much better on the inside ...and will likely be easier to “wallpaper” over later on ...(another assumption )
It’s all a bit Tedious , but then I’m only making the one and that should last for my lifetime at least (save Bears and frozen turkeys) ... If I were making a few of these , I think I’d like to try Heat -forming on a larger scale ..bending large sheets of EXTRUDED foam over big forms ... The Blue or Pink foams are particularly good at heat forming , and only need to be warmed up to 190F to become completely pliable , and the benefit is, once the foam is cooled in a particular shape , it STAYS that way forever ... Things like curved roofs and round noses would be easily reproducible , and a quick fit to the skeleton or framework ... none of this silly bending and clamping and kerfing business ...

One of my wife’s co-workers husband is a fabricator (metal) and really took an interest in the foam trailer idea ... and coincidentally is looking for a “project/business opportunity” ... So the wife, in her infinite knowledge, has scheduled a dinner where we can all get together with Vinnie too and discuss this idea further ... With the availibility of having a metal fabricator , a sculptor/Luthier with a CNC machine , and an old guy willing to stand around for hours cutting foam with a jigsaw , Who knows where this will lead... Three entrepreneurs in one room .. + Beer..

[GPW]

OK, the widened Jigsaw blade works and produces a nice 3/16” wide kerf to just the right depth ... a bit messy , Very tedious , the wide blade slowed down considerably by either the extra width , or the glue I got between some of the teeth ... And as you can see the wider blade tends to “wander” like a drunken sailor ... Not a problem since it’ll al be papered over in the finish ...
But , the panel bends nicely to the required radius ..


Ps. The JB weld is holding , although the blade got quite warm ...

[GPW]

Can’t say this is as much Fun as I thought it would be... took all day to cut/kerf one panel ... that with a couple breaks and a short nap after lunch ... Oh , well ... one panel down , 3 more to go ... Now , I’ve decided to do this outside , cause it just makes a big Mess inside .. and with rain forecast for now through all the weekend, just another delay ...
Going over to Vinnie’s tomorrow and see if he can cut those nose ribs for me ... at least I’ll be getting something done ..

Ps , I did try cutting the slots with the narrow blade first , which went quick , and then chase the slot with the wide blade ... turns out it’s just as much work as just using the wide blade ...and really didn’t work as well ...

[GPW]

Anybody ever try one of those mini routers ? .. Hand held ... small ... That might work with a guide ... Still not totally happy with the jigsaw method ...works, just very slow , cuts aren’t that neat ... (not that it matters) ... Still investigating more methods ... learn as we go eh ...

[Wolffarmer]

That will probably work, but with your thick foam there might not be a bit long enough. You might be able to find a trimmer that has an adapter for a vacuum to make that a bit easier.

[Wobbly Wheels]

That's a laminate trimmer. I have a Makita and I use it more than my big router because it so much handier. On mine, there's a spot where I hold a shopvac hose with my free hand. With a heat gun and a scrap of PVC, you can make any adapter you need, but I think the DeWalt ones have a vac port.

[GPW]

After watching several laminate trimmers in action , it would seem they’re not much faster than the jig saw , with having to move the guide every time ... So got out the jewelers eyeglass and mounted the Fat blade in a vise and picked out all the little bits of JB weld that were between the teeth of the blades ... That May help? it sure feels much sharper now anyway ... Three more panels to go ... 23 cuts per panel @ 10’ long ... and then we get to do the Nose ...

[Wobbly Wheels]

An F-clamp at each end of your straightedge (a straight 1X4 ?) makes resetting it a piece of cake, though you might want to temporarily screw a piece under each end of the foam as well for the clamp to bear on without leaving divots in the foam.
Not sure what videos you watched but I don't see how a trimmer would take more time. Mine's good to about 3/4" ply and 5/8 hardwood - it doesn't even notice foam.

[GPW]

W2, time to go to the store and buy one (money too, they are a bit pricy for one job ) , making a 10’ guide ... etc, etc. I’m already set up with this , have all the stuff, and only have 3 panels to go ... so I’ll stop complaining and just get on with it ... gotta’ “get it Done !!!” Next time though ... things will be different .."if there is a next time ?”

[linuxmanxxx]

Hey Glen the trim router at hf is under 20 bucks and works great.

[GPW]

Steve, never thought of that ... Leaving the house tomorrow , will have to check on that ...

[Wobbly Wheels]

The project has to be enjoyable too, otherwise what's the point. It sounded like you were getting a bit frustrated with your kerfs so I tried a gentle nudge to something that ought to make life a whole lot sweeter - hope I didn't sound like a jerk.

I use mine a lot for little jobs like inlays for knife handles where a regular router is just too big. Perhaps it can go into your luthery toolkit when you're done. I found it to be one of those things that, once you have it, you're always using it.

[GPW]

W2 , I most certainly appreciate your suggestions !!! Going to give it a try ...

Not really frustrated, just thought the kerfing would go a little easier .... The FS is a bit more complicated than making a Box foamie ... I should have realized there would be a shedload of kerfing ... But it’s all good . Learned about kerfing and kerf spacing , and how different foams cut...
I do have to say , the beaded foam cuts waaay differently than the extruded foam ... Extruded makes fine dust ... the beaded foam leaves little beads everywhere... And the beads are a little easier to sweep/vacuum up... but it’s still messy ... Unlike sawdust which immediately becomes part of the earth , foam just hangs around...which I guess is Good in the long run ... for the trailer ...
The reason for the kerf complications was my decision to use the 3.5” thick foam , instead of the 2” thick ... kerfing the 2” would have been easy ... My problem is , my kerfs have to be 2.5” deep ... a challenge for conventional methods ...
Another thing that was immediately obvious .... the smaller width , closer spaced kerfs work much better for uniform bending than the wider spaced kerfs... Twice as much work (or more ) , but worth it IMHO ... And the smaller kerfs are Safer too ... The large kerfs spaced far apart caused much more strain on the beaded foam when bending (broke in several places on the test piece ) ...
The only real benefit (besides being a third of the price of the Pink or Blu ) of the thicker foam is, I’ll have SUPERIOR insulation for those HOT summer months ... Already hitting 90F around here... Just thinking , the smallest of cheap Air conditioners should Cool the FS easily ... and keep it that way ... keeping “Her Grace” happy ... the whole intent of this project ... I’ve already got my Foamie ... ...

[GPW]

Just sayin’ , if I had to do this again (as in mass production) , think we’d try the regular extruded foam , and use the multiple groove cutter shown above ... ^ That George made ..

You never know what can come from a project like this .... there is already some “commercial interest “ ... And EVAC is a popular activity around here , most EVERY Free Ken summer ... A decent size shop with a few specialized tools and you could crank em’ out ...

For future bending , I’m going to further investigate heat forming the Foam , which believe to be better as the foam , once heated , keeps that shape permanently ... no “springback” as with kerfs... Somehow , I feel this is only the beginning ...