The Poet Creek Express - Foamie Hybrid

[OP827]

KC, from info I can find online the vinyl spackle by DAP may be water-based on some vinyl-acetate glue with limestone and quartz powders as fillers. If I were you then I would do a test with coating a small spot of the fully dried vinyl spakle with plain epoxy and let it cure and then see if it peels off or sticks good and go from there. If epoxy impregnates and reinforces the spackle, ie. similar to wood, then it is a good sign. If it peels off from the spackle like from a PVA based glue, it is not good for epoxy coatings.

[KCStudly]

I'll take a closer look at that tonight and compare how well the epoxy sticks to spackle vs. plain foam. I guess I thought my test coupon was an adequate test, but we shall see.

Push comes to shove I can do the "post hole" or razor scarring method to get a good keyed bond on the hatch and front radius. The edges and first couple inches of the underside of the floor may need to be sanded back, or at least significantly roughened up; shouldn't take too long with the palm sander and a course grit.

We'll see what she wants and go from there. Ain't nuthin' gonna stop this train now.

You know, GPW, I think it was Hodder (and maybe others) who asked why I wasn't just using epoxy adhesive for everything right from the get-go. Back then it seemed expensive. Now I am older and wiser, but I still don't know if I would have done anything differently... I still have canvas and glue... who knows?

Ooh La La - The Faces, w/ Rod Stewart and Ronnie Wood

[dales133]

One thing to think about mate if you are going to have adhesion issues is a epoxy 2 pot primer over the offending areas should work.
Sticks to just about anything abd will obviously be compatible with fg.
Micheal could probably shed more light on that.
Nice work mate

[Atomic77]

I use epoxy primers but never used it over vinyl. You are right though about it sticking to almost anything. I've got it on a few things that I did not want it on and once it kicks you can't get the stuff off. I'm unclear though in regard to where you are spraying it. Are you talking about over the foam or...?

[KCStudly]

Perhaps it is just my naivety regarding epoxy paints, but I am assuming that it is just epoxy with pigment added, so I don't see how that would offer a different level of adhesion from the West System I am using for laminating.

My second set of eyes, Karl, who also has some composite experience, is pretty confident that the epoxy will "stick to everything” (I know, I know… not PVA or packing tape, or polyester peel ply, etc.), and if it doesn't it will at least encapsulate. Now on the hatch I definitely want a structural bond to strengthen against twist, so that is why I would consider coring out "post holes". Picture the interior of Frank Lloyd Wright's work the "Great Workroom" of the Johnson Wax Headquarters building.

On Monday I removed the clamps from the TB latch blocks and found that the wet epoxy had crept up under the stretch wrap forming ridges. Ended up sanding them fair.



The West System 403 microfiber filler I’ve been using is probably not the best stuff for making fillets. It doesn’t spread to a smooth texture unless you come back and brush wet over it, so it tends to cure lumpy with nooks and crannies. I had to sand the fillets around the electrical pull blocking quite a bit and will have to hit it with some more during the layup. Considering getting some 406 to try.


To use up some of the bigger strips of scrap glass cloth, I decided to piece together the layup for the stiffening rib on the underside of the TB; cut on a 45 deg bias.



Revisiting the first FG test coupon you can see that the epoxy/glass seems to be well adhered to the spackle underneath, but it is just a narrow strip of the spackle. The area is slightly lower than the rest… not sure if that was in my prep work or if something changed during the layup/curing process… and a little wetter with less weave showing in some areas.


Next I prepped another test coupon. The piece of foam had already been scuff sanded and somehow managed to have some of the gray primer on it that I had been using as a guide coat for sanding the spackle (perhaps this had been my test piece to see if the primer and foam would play nice in small doses). I divided the panel in half; one side to be plain foam, the other to be distressed and spackled. I used the small hand block to sand out a shallow trough (middle); making sure to gouge out a few chunks at one end (lower left); then I whacked it pretty hard with the corner of my tape measure (because it happened to be close at hand), making a triangular shaped dent (upper right).


Sorry for reversing the orientation from the previous pic. Here you can see filler and skim coat of spackle on the right with masking tape protecting the control side.


Spackle skim coat is about 1/16 inch thk.


And with the tape removed.


The blank piece was about 10 x 10 inches square of 3/4 thk foam and weighed 30 grams. With the spackle still wet the blank weighed 50 grams. I will weigh it again tonight, now that it has dried, and again after sanding the surface smooth.


As I was cleaning up for the night I went to move the packing paper that one of the rolls of glass cloth had been wrapped in and had to scratch my head for a few minutes wondering what the heck I was thinking when I labeled this “ass cloth”.


Then I realized that I had written across the seam of the rolled up wrapping paper. Gave myself a chuckle.

[Ned B]

You do realize it will forever be known as 'ass cloth' from here on out right?

[OP827]

You do realize it will forever be known as 'ass cloth' from here on out right?

Ned, I do not think so, but this is funny anyways.

[Ned B]

You do realize it will forever be known as 'ass cloth' from here on out right?

Ned, I do not think so, but this is funny anyways.

which is exactly how I meant it. Pure comic relief

[Mary C]

I not know anything about "glass, epoxy, ect but I do know about ASS cloth but I promis I will not go there. I learned about it when I was sewing that thin stuff making formals for girls to wear to proms. oh another life! I am not sure about what you are doing but I am here watching, I 'm just being quiet....................

Mary C.

[KCStudly]

Ass cloth it is then.

(Not.)

Hey Mary, thanks for chiming in. I'm never sure if I know what I'm doing either.

[KCStudly]

Okay, here we go. Tonight I committed a cardinal sin and did composite layups while it was raining out. 73/ct humidity in the loft at 52 deg F. The horror (sarcasm… it is “only” the bottom of the TB, after all).

I sanded the spackle on the larger spackle/epoxy test panel, cut 2 plies of cloth and mixed up a little more epoxy than called for to do a dry on dry layup.



It may look like there are dry specks in some of the weave pockets, but that is just the way the light is reflecting off of the wet strands.

With the extra wet I added 403 filler and continued making the fillet on the stiffener under the TB. I decided to build this up more so that it came up most of the way to the round over at the top of the rib (the bottom of the rib in situ).


This took a couple more plum sized batches squeezed thru the cut corner of a zip bag like icing a cake. I think I figured out that I have been going too dry on the filler (i.e. too much filler to wet). One of the batches was a little wetter and spread easier (while still not slumping), while another was particularly dry and seemed to chunk worse than before; thus I need to refine my calibrated eyeball when mixing “thick”.

Another small batch of wet painted on the tip of the rib and around the perimeter of the fillet, and I started laying the rib cap glass dry on wet. I’m sure I used a lot more wet than called for on the first ply, but got some of it back when I laid the second ply (i.e. it soaked up thru better than the first ply). I figure that the wood soaked up a bunch of the wet bed, and the drier fillet seemed to take some, too, but I did have some areas that buried the weave so I know it was wet by weight. Still, it all seemed to stay stuck down with no dry spots or blisters and Karl indicated that it looked good.




I mixed in a small amount of 403 to what was left to make a wet “slurry” and laid that onto the chunky fillet around the wiring pull box blocking. That did the trick; much more workable and was able to get a slick fairing.



I had hoped to be able to get the bottom skin wet out and applied with this all in one big layup, but it was getting late so I decided that I could stop here and do that as a separate operation. I’ll have to wash amine and scuff the shine off first, but tomorrow is another day.

[OP827]

Looks great KC, you will find yourself a pro in no time doing dry on dry or dry on wet. And I am not sure that you have to wash amine out if it will be next day, less than 24 hours give it or take if I am not mistaken, the epoxy is still reacting so it will be a chemical bond, especially in lower temps when epoxy reacts slower.

[KCStudly]

I had another read thru some of the West System literature online and it is actually the opposite; because of the slower reaction times in cold weather, amine is more likely to form, so they specifically recommend washing with warm water and a greenie pad, drying with clean paper towel, and scuffing any shiny areas with the pad afterwards.

Unfortunately I didn't think to wet coat the whole underside. If I had I would be able to wash and dry tonight and probably get the skin laid on. As it is now I will have to wait for the wood to dry thoroughly before I can lay the skin ply down.

In other news, did I mention the update on Frankie? Apparently she is very social about the neighborhood. The other day when she came back around she was sporting a collar that someone had fashioned out of that blaze red surveyor's tape, the kind that would stretch and break if it were to get snagged on anything. So Karl wrote his address on the collar with sharpie.

[KCStudly]

It was a good night in the shop tonight. I dissected the spackle/epoxy test piece by cutting it in half across both sections, then peeling one half of the glass off. Yes, like every other test that everyone has done, when peeled up this way from a raw edge the glass/epoxy skin more or less peels right off w/o much resistance.


Remember that this is not a typical failure mode because the edges would be wrapped and the normal loads are either shearing (the panel torqueing or flexing) or impacts. In these close-ups you can see that a lot of spackle came up with the glass.


Here you can see that the foam side took a much more uniform, but thinner, “fuzzy” foam layer.


Here is a side by side looking at the edge of the dividing line. This time the spackle is on the right and the foam is on the left. Yup, we have proven that foam and spackle are not very durable materials, but then we already knew that, right?


So this peeling mode of failure could happen in two scenarios that I can think of. The first would be if the camper flopped on its side and slid down the road far enough to grind off the glass at a leading edge; then something would have to wedge or snag this edge in order to pull or peel the glass layer back in this fashion. Highly unlikely and it would be a “bad day” no matter what, regardless of construction technique and materials. The other much more likely scenario would be a big dead pointy tree branch along the side of a tight trail poking into the side or roof of the camper, puncturing the skin then ripping outwardly in a can opener like fashion. This type of hazard is fairly common on tight woods trails that would be typical of a 4x4 off road outing in the Jeep, but less likely to encroach on the types of roads and trails that I will be taking the camper. Usually this type of hazard is visible in plenty of time to avoid or to stop and clear by hand. Sure, there could be a tree fall on the Magruder that I might have to clear, but the forest service road is generally fairly well maintained (in context) and this type of hazard would not be predominant.

You say that it sounds like I am justifying my results, or rationalizing? Okay, here is a true delamination acid test. I bent the remaining test piece into a ‘U’ shape.


No signs of any distress (other than the foam on the ID of the bend compressing) and no evidence of any delamination. I did this separately for both the spackle side of the panel (shown) and the foam only side. Same result on both sides. That, folks, pretty much settles the argument for me. I am no longer worried about glassing over spackle. (That’s a period at the end of that sentence.)

My concerns about getting the plywood bottom of the TB wet while cleaning off the amine blush from the rib stiffening was unfounded. I used a wet paper shop towel to wipe the glassed areas down in a very controlled fashion and kept from saturating the wood at all. Before you could definitely feel the somewhat slimy coating of amine; after you could feel that studder bump (stick slip) thing when you dragged your rubber gloved finger across it. Squeaky clean.

From there I hit it with the greenie pad to scuff, and some 100 grit along the edges and where there were small nubs here and there. Here it is all ready for the next layup.



Moving forward I unrolled the PMPP package with the rough shaped cloth and taped the bottom sheet of plastic down to the bench. Got everything ready and did the calculation for how much resin I would need to wet the cloth out. Unfortunately I forgot that I only had one ply, despite having written it clearly on the plastic to remind myself. Doh. So I ended up mixing up a few too many ounces of wet. I did figure this out before dumping it onto the cloth, so just poured about half. Got the cloth wet out, put the top sheet of plastic down, squeegeed that down, then cut out the pattern, including the slot down the middle to straddle the stiffening rib.

From there I used about half of the remaining wet to coat the plywood bottom. Using a credit card to spread most of it out quickly worked well, then a chip brush to get right up to the edges w/o pushing too much over and having it run all down the sides. Coated the overlapping area around the rib and the raised area of the pull box block.

About this time Karl came up to the loft. He always has good advice and will chip in a hand as needed. As I was folding the prepreg package over to peel the bottom plastic and mentioned that the slot would make it extra floppy, he suggested that I just peel back half the plastic and cut it off (kind of like a split back decal or band-aid). Between that and picking the piece up by the folded ends (to better control each leg of the folded slot) I was able to position the largish piece fairly accurately over half of the bottom (after a couple of initial attempts). Moving the prepreg around to get it lined up is actually pretty forgiving with the top plastic still on. You can lift and drag pretty aggressively and the plastic takes all of the tension without stretching or skewing the cloth, so long as you haven’t really stuck it down good yet. Then it was easy to peel off the other half of the bottom plastic and unfold the rest to lay it down.

About this time I had Karl get the camera and start taking some video. Wished I had thought of that sooner. He caught me squeegeeing down the prepreg with a Bondo spreader. With the 6 mil plastic you can get really aggressive with the Bondo spreader without fear of wrecking anything.

Then I demonstrated how to peel the top sheet of plastic off without lifting the glass too much. This went very well on the nice exposed flat surface where I could pull down on the edges of the glass and pull the plastic straight across back on itself.

I’ll have to edit and dub over the audio before posting the vid on u-tube because I had the radio playing in the back ground and who knows if they will allow popular classic rock to be freely shared (as is done on the radio, doh). I’ll try to get to that this weekend.

Anyway, this was probably one of my best layups to date. I might have used a little less wetting on the plywood, but all in all there doesn’t appear to be any dry areas, blisters or lifting along the edges. (The white ghost areas around the T-nuts are where I skimmed with 403 filler, not dry).



Tomorrow after work I need to get enough glass to complete the outside of the box. Then I will trim this layup and round over the bottom edge of the ply so that the side glass can wrap under easier. Might even get the side glass cut out and ready for the next stage.

[KCStudly]

Took a few more bites at the elephant today. I decided that there would still be plenty of flat surface area for the TB lid gasket even with the rim round over increased from the original 1/8 inch radius to 1/4 inch radius both inside and out, so I went ahead and ran the router around the inside edges and along the side edges. The front and back edges aren’t a 90 deg angle, so I had to do those by hand using the matchbox plane and small sanding block.



I did some more bodywork on the sides of the box and while that was setting up I cut the glass blanks for the back of the box (2 plies), and for the front and sides (the latter as one section in 2 plies). I considered buying more of the 38 inch cloth, but when I figured out the sizes and yields it turned out that it would cost more and I would have more scrap using the 38 wide than if I split a shorter piece of 60 wide in half lengthwise. I figured it would be just over 3 yards to get 2 plies, so I bought 4 more yards. In the end, because the clerk gave me a little extra to account for the uneven cut edge, I ended up having 35 to 36 inches left over. Since my workbench is not 60 inches wide, I unrolled the glass from front to back on the bench, using the edges of the bench and lines drawn on the plastic to keep things square, and cut up the middle. Since the bench is only about 4ft wide, I did this in 3ft sections and rolled the resulting halves up as I went. First the two plies for the back of the box at about 42-1/2 inches long, then the front and sides pieces at about 74 inches long, total.

From there I turned the longer pieces and again lined them up with the bench. As tempting as it is to continue using the PMPP technique, this piece may be a bit large for that and I figure I need to work more on my dry on dry technique before getting to the hatch. So instead I made some reference lines directly on the glass that I hope will help me lay it on the box accurately.

Here are the two plies for the front/sides laid on the front of the bench.


And here they are with the 2 inch allowance for wrapping under the bottom of the box (along the bottom), the locations of the side corners, and the profile of the rim at the top.



The plan is to wrap the bias cloth over the rim next, then have this piece cap that running up flush to, or just under the rim. I was reluctant to cut the top profile yet, for fear that it would fray before I can get it on the box. Tempted to go back to the PMPP here, but will see what happens as I go.

I used the angle finder to transfer the side angles to the bench, bisected those angles with the compass, and then used the angle finder again to transfer these angles for the darts at the bottom (dart angle equals half miter angle, I think).


One last task for today was to clean out the t-nuts in the underside of the box for the rubber mounts. I decided to do a tutorial style of documentation here, so step by step. Recall that I wadded up plastic stretch wrap, screwed it into the threaded holes and trimmed it flush before glassing over. Here you can see one of the 5/16-18UNC T-nuts for the battery hold down on the left and the darker circle for one of the 3/8-16UNC mount studs on the right.


To start I used a small drill bit, eyeballed center from a couple of axes, and just spun the bit by hand to make a center mark. Later I found that I could easily drill a pilot hole by hand if I wanted to.


The center mark.


Being that the plywood floor of the box is only 1/2 inch, I didn’t want to accidentally drill thru the inner skin if the drill happened to catch, so I made a stop block for the pilot drill.


Then drilled out the center mark.


Then I drilled up to 1/4 inch exposing the stretch wrap packing.



Next I used the spike on the compass and the tweezers to pluck the stretch wrap out of the hole. This took a little bit of doing, but in the end the results were well worth the small effort.



A larger drill bit and a little hand twisting started the deburring process.


Then I laid the bit over and used a little more twisting going around in a conical orbit to clean up the edge.


Later I found that a nice sharp blade in the utility knife, used in a downward angular/circular slicing motion worked even better.



Finally, I used a little scrap of 100 grit sandpaper to finish things off.


The finished hole turned out as well as could be expected, which was very nice!


The studs on the rubber mounts were 3/4 inch long; too long for the 1/2 inch ply; so I spun a nut on each and sanded the tip back and re-chamfered using the Bader belt sander. I took care not to overheat during sanding, so as not to disturb the rubber bond.


This allowed the mount stud to fully engage the T-nut without poking thru or lifting the glass layer on the other side.


Wash, rinse and repeat three more times and we have rubber mounts all ready to go. I’ll take them back off to paint, but for now it is nice to have the box standing on its own four feet!




I like how easy it was to trim the bottom glass on the TB using the relatively crisp corner as a guide, so I think I will glass the rim and back next, then use the hard surface of the cured back as a guide for the round over bit bearing and radius the rear corners of the box for the front/side layup to wrap onto the back easier. That’s the plan for tomorrow.