The Poet Creek Express - Foamie Hybrid

[OP827]

Your both surfaces are non porous, except foam has kerfs. it may require more time for PLP to setup, unless you put some moisture in. Did you do this glueup somewhere else?

[KCStudly]

Both the foam and epoxy/glass have enough tooth to grab using either of these products.

And I can press the foam into the adhesive by hand and smooth the panels down easy enough. The hard part was holding the front panel everywhere long enough for the adhesive to grab and set. On the gently curved top of the roof with the foam fitting snugly between the spars it pretty much took care of itself. On the tighter curve at the front it was a different story, and presumably will be again on the hatch.

The problems with the traditional straps on the foam is that the foam is not stiff like plywood so it doesn’t transmit that strap load away from the point of application well. The strap could be pulled very tightly, but would (potentially) crush the foam under it while just a few inches away the foam would lift. Juggling wood under straps didn’t solve the problem; it just shifted where the point load was applied. With the stretcher it applies the force evenly and gently over a broader area, and it just doesn’t take that much force if it is applied correctly. A small force applied evenly does the job.

So to do the actual glue up of the front curb side panel I first traced the dry fit panel with a sharpie so I would know where to put the adhesive. Then I spread the adhesive and stuck the panel down. This is about the limit on what I am comfortable spreading with the PL300; it started to get a little draggy by the time I actually had the panel down. Part of that was because I tried to use some GS along the top of the locker (to fill the factory cove in the edge of the foam) and along the wall edge to fill the kerfs, but my can of GS wouldn’t cooperate; nothing would come out despite having cleaned the nozzle first. So I had to back track a bit and lay some more PL300 in those areas. Anyway, the stretcher clamp worked as advertised. This is after running a damp rag down the edge, mostly just to clean up where I painted outside the line, with just a thin bead of squeeze out.



The cord clamp method left room to install the second layer of foam next to the locker bump out on the street side where the shovel mount blocking is.


My math isn’t so good tho, the 2 layers of 3/4 inch foam are thicker than the 1-1/2 inch tall blocking and 1x2 rock guard "sparette".


There will be lots of sanding foam in my future.

While I was at it I put the second layer in the street side fan bay. Same thing; sticks up a bunch in the front. It looks like it sticks up less in the rear, but the foam there has a bit of a rolled or crushed edge, so it is actually higher than it looks.


Front edge.


Back edge.


Seeing a lot more sanding of big curved profile in my future, and having glued all of the pre-fit foam that I could, I found a drop of 1/2 inch ply that had a curve warped into it and another scrap of 1x with a curve warped into it, and banged together this sanding board that closely matches the roof radius.



I know what I have to do to finish the front and roof foam, so while that front panel was kicking off I started looking ahead to the hatch area foam again. I need to settle the locations for the lighting (galley, license plate and tail), and once and for all decide if I am putting blocking in for the handle or not. Inspired by Atomic77’s tail light work, I decided to zoom in on the tail light mounting nacelles. After all, it will help me figure out where the wire runs need to be in the foam.

The plan is to make 5 mm plywood mounting surfaces backed by some 1x1 maple blocks for the mounting screws. These will be set into foam blisters that hold the lens vertical, provide the necessary depth for the wire harness plug, and fair into the curve of the hatch. Here is one of the tail lights, the layout of the mounting surface, and the maple screw blocks.


Close up of the mounting layout. The inner oval is the cutout for the fixture; the middle oval is the footprint of the chrome flange; and the outer oval represents the edge of the mount giving a consistent margin.


After ripping to width on the table saw and rough cutting the end radii on the band saw, I used Karl’s bench mount disc sander to sand to the lines. (This is one of the first tools he bought when he started the current business, but he seldom ever uses it anymore, tending to prefer the Bader belt sander. I scraped the rest down with a razor, buffed it with an abrasive pad and hit it with some paste wax before using it.)



Lather, rinse, repeat.


And that seemed to be a good stopping point for today (Saturday, er… technically yesterday).

[Wolffarmer]

I bet a hunk of Tyvek would work instead of the paper you are using. But I do not have any to test if the glue will stick to it. Probably will.

[KCStudly]

I bet Tyvek would work really well.

I was asked to stay over tonight and finish a conveyor cover for a bottling line (think snot shield on a salad bar and you won’t be too far off). I was a bit pissed because the task has been known to be needed for weeks and it didn’t become a priority until the very last moment. I’m very disappointed that I didn’t get to go work on the camper tonight.

As a bit of a buffer, I am posting a couple of pics of the first front foam piece now adhered. On Monday I went out and, after catching up on the Pizza Oven Trailer, I pulled the stretcher off of the glue setup. No issues except the piece had shifted slightly where the upper edge was hanging off the side a tad more than the bottom. No biggie, the outside will get trimmed flush anyway and I’ll make it up in the middle by using a slightly wedge shaped filler.



Re: the PL300. I like it. It stuck well and seems to stay more pliable, almost rubbery, compared to the PLP. I expect that it will be easier to sand, too, so long as it doesn’t just ball up and clog the paper. We will see. I have gone thru a bunch of it using it for 100% contact, but it is also water resistant, so that is important. I’m now thinking that I may cut back on the coverage when I get to the second layer of foam, perhaps saving the 100% coverage for the spar sides and a bead to make sure the edges of the first layer are good and sealed, then use the label recommended coverage for the foam to foam field areas.

[GPW]

Maybe some 1/4” foam sheet (FFF) for those little fill-ins ? ... rather than sanding everything else away ...

[KCStudly]

Well there will need to be some trimming and sanding anyway because I let the roof foam run a bit long over the edge; better to have extra than not enough.

I had always thought that I would just squirt GS in the gap between roof and wall and do the fairing all at once, but the idea of inserting a strip of foam is worth looking into.

I'm not sure I was clear; because of the 64 inch width, when I cut the full length pieces for the outer roof layer of foam a little long at 64-1/4 inches + saw kerf, that left the short pieces for the first layer at less than 32 inches each. So I have been adding a narrow 3/4 x 3/4 strip of foam down the middle of the roof to compensate and still allow the first layer to run off the edge. It is this middle strip piece on the front above the locker that I will use to compensate for the first curvy piece being a little crooked. That center strip piece will need to be slightly wedge shaped.

[GPW]

Huh ? What ??? We’re gonna’ need a picture of that ... (sorry, still early )

[KCStudly]

Walls are 64 inches outside.

Foam comes in 96 inch (8 ft) lengths.

Cut a bunch of 8 ft sheets to 64-1/4 inch for the top layer of foam (64 inch wide plus 1/8 inch overhang each side for fudge to be faired to the side walls later) and you are left with a bunch of pieces at 31-3/4 inch.

Two pieces at 31-3/4 inch only gets you 63-1/2 inches so I need to add a 3/4 inch wide strip running down the middle of the first layer to get the same overhang. You can see the center filler pieces here in this pic looking forward from the galley.


So a typical spar bay consist of a three piece first layer to be capped by a single piece top layer. The hatch and front radius spaces are longer than the 2 ft wide stock size of the foam, so those areas will naturally be pieced together from more panels, but will still be made up of full cabin width pieces for the top layer.

The other issue is the blind dado like gap between the tops of the walls and the under side of the roof foam. This is where I held the 5 mm ply ceiling panel back from the outside of the walls by a 1/2 inch (IIRC) per side. The reasoning was mostly because it improved my yield on plywood sheet count (I was able to get a few more larger pieces out of the drops due to that extra inch), but I also rationalized that it would give me an opportunity to totally encapsulate the edge of the ply before canvasing. That gap can be seen here along the edge of the roof to wall join. See how the ceiling panel ends before the end of the spar and the roof foam extends a little further still.


I was planning on filling this gap with GS and then fairing the whole mess back to the surface of the walls and ends of the spars, and then finally rounding over the profile with the 3/4 inch radius.

Clear as mud or still need to drink more mud (joe, java, coffee)? (I'm on my first cup still, too. )

[GPW]

Got it !!! Thanks !!!

[OP827]

PL300 glueup looks really nice . About the sanding of the extra foam that is proud of the roof spars - would that be easier just to glue a thin piece of wood or thin ply on the spars to be even with top of foam (after the foam is adhered to roof of course) and avoid that large areas sanding work? Just a thought. I could be missing something here though, was not reading everything, sorry.

[KCStudly]

You may be missing the fact that the spars have a 3/4 inch radius on the ends and the plan is to match this with the foam so that the canvas rolls around the corner nicely. Also more pleasing to the eye w/o edge trim to have a radius.

Your comment has given me a real time saving idea, tho. I can screw a temporary strip of thin ply along the tops of the spars with its outer edge very close to flush, just proud by a hair or two, then use it as a guide for the top bearing bit in the router to bring the excess foam in close and save the last little bit for sanding; rather than risk hacking the rough cut with the steak knife or sanding a mile.

Thanks for that.

I still think the radius needs to be done by hand because it is a compound curve in one plane and there is no hard surface for the bearing on the radius bit to follow in the other plane.

In hindsight, I kind of wish that I had planned a hard edge all along the profile instead of just in way of the galley.

Oh well, this will work, too.

[OP827]

KC wrote: "You may be missing the fact that the spars have a 3/4 inch radius on the ends and the plan is to match this with the foam so that the canvas rolls around the corner nicely. Also more pleasing to the eye w/o edge trim to have a radius."
- No, I do not think I missed that part. I thought that adding the strip on top of the spar will slughtly distort existing 3/4 inch radius on the spar ends, but if the foam is only slightly proud above the spars and when it is rounded and done, this slight out of 3/4" radius edge will not be noticeable at all, will it?
BTW, I do prefer rounded edges to sharp ones, I will be doing similar radius on the edge of my roof part. It looks more contemporary to me.

[KCStudly]

Oh, I'm sorry. I misunderstood what you meant. As usual, I over complicated it.

You mean why don't I cap the spars along their lengths with thin slats to match the height of the foam? Yes, that idea has real merit!

I think I will wait and see how the foam heights end up on either side of each spar. If one side is high and the other is flush, or close to flush (which from my initial checks seems likely) it might not be so practical. The other thing is I want to make sure the profile looks smooth to the eye, not segmented.

Karl posited the option to use my hot wire cutter (which, ironically, I have not used on this project to date) and just skim across from side to side using the spars as guides, but I thought that would give too much of a faceted look and I want it to be a smooth arc.

Had to slog it out at the day job again today, but still managed to get to Mecca for a couple of hours. Downstairs shop smelled like paint thinner and there was primer overspray where the Pizza Oven Trailer had been, so I assume Karl was down in Madison with it.

Not being very energetic, I decided to tinker on the taillight blisters, rather than the roof. I took this chunk of 1-1/2 inch thick foam from the scrap pile, traced both of the light flanges, set the 3/4 inch bit depth to match the 5 mm ply, and just free handed the mortise. Most of this will be trimmed away and shaped later to get the two parts out of it.


I left plenty of waste in the center… no reason to remove it at this point and it helped support the small base on the trim router. I find it fairly easy to follow a line in foam if you go slowly so I didn't bother with a template. Small variations won’t matter in this application.

Used the scroll saw to cut the centers out of the flanges. Spent some time sanding the opening a little larger on one of them as it was a little tight for the light to slip in. The other was looser with plenty of clearance.


Trial fit in the mortises.




Finished up by gluing the screw blocks on. I set them flush to the inside and will sand them on the wheel as needed to flush the outside off.



Let’s do a little crystal ball gazing. The plan going forward is to sink the screw blocks into the foam, glue wood to foam, route out the center foam, and decide where to put them on the hatch. Once that is set I can figure the contour needed on the back to set the lenses plumb. I’m thinking this is a good place for the hot wire cutter: make a pair of templates; mount them on either end of the individual foam blocks, and scoop out the concave shape to match the arc of the hatch. Then maybe double tape the plug back in place to maintain the flat back reference, tilt the table on the band saw and cut a bevel all around.

Train kept a rollin’.

[OP827]

Looks good, KC.

[KCStudly]

To quote Elvis, "Thank you, thank you very much."