calicamper
Expedition Leader
The change in ply type might affect the amount of bonding agent need per panel. The dry spots could be due to their switch in ply type. Different absorbsion etc. Cool project
ultra compact slide in / sleeper
- Thread starter Gunner207
- Start date
Well, I got the sample box today, and I've been playing with it. Cut about a 1"x4" piece of the plywood-PP core material and stuck it in boiling water. One side promptly came loose! So I cut off another piece. Same thing happened. Little or no glue on one side and the plywood just came loose from the scrim on the PP core. The other side appears to be bonded ok. Looks like a poor glue job.
The plywood is very light stuff, significantly lighter than 2.7mm luan from Home Depot. The sample I received with a 10mm core, weighs ~.71 lb/sq ft.
On the bright side the glue inside the plywood layers appears to be holding up to boiling water, but then so is the luan.
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Update. Left the samples in boiling water for 3 hours. One side of the plywood-PP core continued to hold well. Unfortunately it was easy to pull the plies apart, so the glue was definitely not holding within the plywood.
Side note, I'd considered just buying the core and putting my own skins on (fiberglass outside, plywood inside). That won't work though. I live at 7000 ft and there is a little bubble at every cell. Gluing on plywood might work, but fiberglass layup would be bumpy.
Side note, I'd considered just buying the core and putting my own skins on (fiberglass outside, plywood inside). That won't work though. I live at 7000 ft and there is a little bubble at every cell. Gluing on plywood might work, but fiberglass layup would be bumpy.
1 Bored Clerk
Explorer
Disheartening to hear about the glue issues being found. I'll need to order a sample pack and see what I get. Have you contact carbon core to let them know about this? If not, you should so they know there is an issue.
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I'll definitely contact them tomorrow. When I talked to the rep earlier about the plywood panels he didn't sound very enthused about them. Said they didn't sell many and that they didn't have any in stock, and it would take 4 weeks to get them. I wonder if it's a known problem and is getting fixed?
I'm thinking about the fiberglass skinned panels now. They are $208 for 1" but they seem real solid and have some advantages over plywood. The big disadvantage is fiberglass dust when cutting.
The PVC foam seems really solid also. That's ~$100 for 1" and I'd have to do the skins myself.
I'm thinking about the fiberglass skinned panels now. They are $208 for 1" but they seem real solid and have some advantages over plywood. The big disadvantage is fiberglass dust when cutting.
The PVC foam seems really solid also. That's ~$100 for 1" and I'd have to do the skins myself.
1 Bored Clerk
Explorer
The dust is really the only thing keeping me from fiberglass panels but it's not a huge issue...especially if they are a proven product. Also, I'd want them to come pre sanded for additional fiberglass bonding. I'll have to see if they have that option.
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calicamper
Expedition Leader
When I was involved with building high end racing sailboats the Builder due to materials availability switched to a different foam type for cored areas. Each core type has its own speced / engineered wetting cook book to achieve full wet through. The builder didnt have a cook book for the new foam type. As a result it was a very cosly mistake.
Ply skin bonding to a foam core works in a similar manner. Both the foam and ply type can change the cook book process for full wet through.
Its also possible the samples are being cut from bad panels without the company realizing the samples are being fully tested which is what most product builders will do before investing in the full build process and material.
Ply skin bonding to a foam core works in a similar manner. Both the foam and ply type can change the cook book process for full wet through.
Its also possible the samples are being cut from bad panels without the company realizing the samples are being fully tested which is what most product builders will do before investing in the full build process and material.
I didn't see that on their site, but they do list a panel with double thickness skins. The skins on the sample I got are ~1mm thick which seems like a lot for a single layer 18oz cloth layup, but I really don't know.
1 Bored Clerk
Explorer
Gunner207, if this conversation is clogging up your build, just let us know and we can go somewhere else. It's very helpful to be in on the ground floor of a discussion like this that's up to date but I would understand if you want it elsewhere.
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I thought that also, his build thread has turned into a discussion of structural panels. Which he happens to be using, but still...
This is absolutely fine with me. I think this makes sense. I got the heat turned on in the shop and cut the blank for the camper floor tonight. I'll start posting progress each day and will try to come up with as many methods as I can for joining panels. I have quite a bit of experience with composite construction, etc, so let's all pass thoughts and problems back and forth.
I really like using temporary fasteners for holding things together while adhesives / epoxy cures. There are also some flexible setting epoxies that I would certainly consider on a larger build. I am thinking of making a mold along each panel seam with thin stock either covered with packing tape or pva mold release and tacked in place with 23ga pins. Then I would reinforce all the seams on the outside with 3 inch bias cut fiberglass tape in epoxy. The whole framework could be a single lay-up.
Stay tuned for photos starting tomorrow and please all of you feel free to make suggestions, ask questions, or even offer critical input. I can adjust or even do some sample joints for ideas you might have. Remember in everything, it is so often the best case to not be an expert because then you don't know how it is supposed to be done.
I really like using temporary fasteners for holding things together while adhesives / epoxy cures. There are also some flexible setting epoxies that I would certainly consider on a larger build. I am thinking of making a mold along each panel seam with thin stock either covered with packing tape or pva mold release and tacked in place with 23ga pins. Then I would reinforce all the seams on the outside with 3 inch bias cut fiberglass tape in epoxy. The whole framework could be a single lay-up.
Stay tuned for photos starting tomorrow and please all of you feel free to make suggestions, ask questions, or even offer critical input. I can adjust or even do some sample joints for ideas you might have. Remember in everything, it is so often the best case to not be an expert because then you don't know how it is supposed to be done.
WanderingBison
New member
I have been reading this thread since day one and I want to thank you! Please continue to share your wisdom and experience.
I hope to start sharing my own plan/build in the coming weeks (if I can get over the "stage fright" of sharing my newbee-ness in front of this brilliant community) and composites will be my materials of choice for "the box". But there are quite a few choices, so many things to consider and I'm learning so much from this conversation.
Thank you!
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CoyoteThistle
Adventurer
Congratulations on getting the build started! This should be good...
FWIW, I used simple butt joints in my construction. I used thickened epoxy adhesive compound to slightly overfill the "end grain" (= exposed core material) and then clamped that to the plywood part of the other panel - this worked for me because I used 90-degree joints almost everywhere. I then added a fillet to the inside corner and used 3-inch fiberglass tape. This leaves the end grain of the other piece exposed on the outside of the corner so I filled that thickened epoxy, sanded and then used 6-inch fiberglass tape or bonded aluminum angle to it with 3m 5200. The aluminum angle is not welded (to answer an earlier question).
You can kind of see the process here (before aluminum):
This was the simplest approach and made strong enough joints for my liking - but, almost any other approach (those that Gunner has talked about) would surely be stronger. It is also a slow approach - each piece stays clamped over night and the clamps have to be removed before the next piece goes on. Typically I'd re-measure the "as-built" conditions after removing the clamps and then cut the next piece to fit exactly to my "as-built" reality - it was usually very close to my as-designed measurement but for an amateur like me, it was nice make up for small errors as I went along.
Stoked to see all the interest in small composite DIY campers!
FWIW, I used simple butt joints in my construction. I used thickened epoxy adhesive compound to slightly overfill the "end grain" (= exposed core material) and then clamped that to the plywood part of the other panel - this worked for me because I used 90-degree joints almost everywhere. I then added a fillet to the inside corner and used 3-inch fiberglass tape. This leaves the end grain of the other piece exposed on the outside of the corner so I filled that thickened epoxy, sanded and then used 6-inch fiberglass tape or bonded aluminum angle to it with 3m 5200. The aluminum angle is not welded (to answer an earlier question).
You can kind of see the process here (before aluminum):
This was the simplest approach and made strong enough joints for my liking - but, almost any other approach (those that Gunner has talked about) would surely be stronger. It is also a slow approach - each piece stays clamped over night and the clamps have to be removed before the next piece goes on. Typically I'd re-measure the "as-built" conditions after removing the clamps and then cut the next piece to fit exactly to my "as-built" reality - it was usually very close to my as-designed measurement but for an amateur like me, it was nice make up for small errors as I went along.
Stoked to see all the interest in small composite DIY campers!
That should be plenty strong if it's done well. Was the thickened epoxy fill on the edges tricky or difficult? Did you use wood powder or something else?