So I am making a hollow wood surfboard for my son (practice for mine!). I made a hollow bodyboard for him first as practice. I didn’t like sanding through the glue, so I thought making the boards for the top and bottom with epoxy would be simpler… This made the actual build very easy, but when it came time to bend it to the frame… Cracks… It seemed the bond was too brittle for the bend, as the cracks were all at the seams. I have filled twice and still am slowly filling in here. I used Fiberglass Hawaii 2:1 surfboard epoxy, and have filled some with their 3 min epoxy. One cheater’s coat on and I am still filling in all these cracks (and trying to sand down all these low spots). The hairline cracks that are all over are more the issue. They are water tight, but I assume I need to fill them all in to the surface to avoid bubbles. This is a huge time waster (I have very limited time to spend in the garage as it is). Any hints? Has anyone used epoxy successfully for their deck and bottom?
[img_assist|nid=1075640|title=Crack in top deck|desc=|link=none|align=left|width=100|height=75]
The worst crack
[img_assist|nid=1075641|title=Bodyboard|desc=|link=none|align=left|width=75|height=100]
The Demo bodyboard
The first post was not totally clear to me. But I think you used epoxy resin to glue the planks together, before applying the decks to the frame. When you clamped the decks on, the seams cracked.
I would fill all the cracks to the surface, sand the whole thing, and glass with 4 oz. cloth. Otherwise I think you will have problems down the road.
Remember, hollow wood surfboards create a suction (air inside contracts) when they go from land to water, and even the tiniest pinhole will take in water.
Huck - yes, I used epoxy to form a plank and then steam bent it onto my fishbone frame (but apparently didn’t steam it enough OR using epoxy for that step was a mistake). The bodyboard had planks that were glued with Titebond III. It was a pain to sand. I am contemplating building a sander so I can pass the planks through and get an even depth. I am wondering if epoxy is just a bad choice.
Todd
[img_assist|nid=1075646|title=Bottom plank on frame|desc=|link=none|align=left|width=75|height=100]
[img_assist|nid=1075645|title=Rough finish HWS 6'6"|desc=|link=none|align=left|width=100|height=75]
I would not use epoxy resin as a glue without a thickening agent. You can buy two-part epoxy glue made for that application.
Hmmm - sorry. Jumping between devices… Should I post a “preview” to get a bigger pict?
That, looks so complicated…Ease up on the engineering my friend…
I’ve never had issues edge gluing boards to make a panel with epoxy. The seams never opened up when bent up to the stringers or down to the rails. The wood would split before the seams break.
Use thickened epoxy on one board before joining to second, but use unthickened epoxy on both mating edges before joining the boards with the thickened epoxy. Otherwise the thirsty wood pulls the epoxy out of the thickened epoxy, making for a poor bond.
http://www.systemthree.com/reslibrary/literature/The_Epoxy_Book.pdf
I recently had similar issues with a compsand, the deck skin cracked in the glued seams. I asked one of the more experienced compsand builders what he did to avoid this, he said he glassed the inside first. Would solve my issues, and probably yours too, atleast the cracks would be smaller and thus easier to fill. You could probably use 2oz or even 1oz cloth on the inside if weight is an issue. As a bonus the inside is sealed so you don’t have to worry if you get water inside, just coat the frame with epoxy too.
Very good advise by all here. You say you glued your planks together then steam bent to fish bone frame. Used fiberglass hawaii 1+2 epoxy. Fiberglass hawaii is good resin for glassing but not for useing as a glue or filler. It is a hot resin that actually exo therm and crack if uses as a filler. Also steam bending anything that has been glued with epoxy or tight bond glue will fail. The failure point for most epoxys is about 180 to 220 degrees. Yes there are epoxies that are heat cured but must be bought special order and still would not work with steam bending. Always use a filler when useing epoxy as a glue. Tite bond creaps and is not the best glue for wood that is to be bent or expected to stay bent. Yes glass the inside when you build whenever you can. I use West systems epoxy for all structural glueing and filling. I prefer Aerialite for my glass work, But some times Fiberglass Hawaii if I don’t have Aerialite or West systems 207. Aerialite is the clearest of resins and has given me the best long term finish when exposed to UV. As Paul says don’t over engineer your projects.
What filler is suggested for gluing applications with epoxy? I have used cabosil and chopped fiberglass in surfboard repairs using resin. I used sawdust to add color around the air vent and leash plug of the body board. If Titebond III isn’t a good glue (used because of its waterproof qualities) to bend, is there another recommended glue?
[img_assist|nid=1075679|title=Detail of Delfino logo|desc=Redwood sawdust mixed with epoxy for filler|link=none|align=left|width=640|height=544]
I used to edge glue many boards to make a bottom panel, but later started taping them together tightly from the exterior, then flipping the panel and glassing them together, pouring the epoxy out over the seams and letting it penetrate to the tape, then spreading it to the rest of the cloth. This can allow for thinner planks/ less weight.
For a thickening agen, I had bought a gallon of system 3 wood flour a decade ago I still have, but if you can collect a fine dust from say 150 or 220 grit of the same wood you are using, no need to buy anything.
I rarely use it anymore.
If there are any voids, I now mix up a batch of epoxy, and spread it out on some scrap wood to thicken. Once it is a little thicker than peanut butter, I pick it up with a razor blade and squeegee it into the voids.
Thanks wrcsixeight,
Are you using steam on your bottom deck? Which rail system / internal structure are you using? I assume from the fact you only use it on the bottom that you are doing the decks as individual strips. I like the idea, and could maybe bring the height of the plank from 1/4 inch to 1/8 inch… But the method I am using for the build (fish bone structure with bead and cove rails, top and bottom planks) would mean gluing / epoxying the glassed side to the frame and the strips for the rails. One of the reasons I was unhappy with my epoxy choice is that I enjoyed hand planing for finishing the bodyboard, and epoxy made that difficult (it chipped and caught). I ended up sanding everything.
Todd
I would like to see a close-up shot of that adjustable rocker bed/form you got there.
Tools are kinda my thing.
Especially home made ones.
Cool looking board too.