Hey dude that sucks. Learning process for sure here. From what I see online PETG should be able to bond ok to epoxy at least as well or better than PLA. I wonder if the hardboard solution wasn’t bendy enough in more than 1 direction to press the fiberglass evenly along the board and get a good bond. It’d be hard to find something bendy enough but not too bendy that it dimples… might need to 3d print like a negative mould or something.
All is not lost and you should still be able to reuse that print I bet. I ripped the glass off a couple of my boards and reused them after grinding them down. Maybe give your blank an aggressive sanding to get it back to the bare plastic and then try the last method I used unless you had something else in mind.
Roll epoxy onto the blank.
Apply large tissue sheets and smooth by hand. Let dry.
Sprtiz lightly with water or a mix of water/acrylic sealer and let dry to tighten
I’ve run into the issue of funding this project vs some other stuff that may actually make some cash
So this is likely going on the backburner for a bit. Which may be a good thing overall.
I am quite keen to try the heat shrink dacron route. The idea would be to use heat n bond to apply the dacon (tested and it bonds decent to PETG), iron it tight and then seal that up with acrylic concrete sealer. And then apply the fiberglass over that. Some SOF kayak builders are using that method. Should be a better bond I’d imagine, but for now will have to be on hold
This ties in nicely to another thread about why there isn’t more innovation in surfboards.
My take was it’s the economics.
You’re engineering and R & D throughout this thread is pretty amazing, and you clearly have some extremely valueable skills that would be very welcome in many engineering environments that pay knowledge workers extremely well while working on really cool technologies.
Yep. I’ve always thought “why is PU still the dominant construction in the lineup?” Well, with UV resin you can make an entire board in 1 day start to finish and the cost is as low as it gets. From a pure business stand point where people will pay nearly the same price regardless, it just makes sense.
Moving forward on the project. I decided to do tissue paper since I really want to get this done. I did the epoxy and then when it gelled up a bit covered in tissue paper. It’s nice and taught at this stage.
This morning I mixed 50/50 acrylic concrete sealer and water and misted it over. A bit concerned with how much it sagged, but supposedly it will tighten up as it dries. Semi skeptical, but we will see.
I was pretty keen on 4/4 glass on both sides, one being S cloth and the other E. But I am beginning to be a bit worried about puncture resistance.
I may go 6/4 but I am also thinking about doing a full length fabric “inlay” across. It would add a tighter weave which may be better for puncture resistance, and the right fabric that goes semi translucent could be really cool with the light being able to penetrate.
That’s awesome! Excited to see how it turns out. The paper should dry within an hour or two and tighten up. At least mine did. Its a fine balance to not overdo it with the spritzing and less is more I think. Seems like magic when it works well. If you do too much and the paper sags a lot you’ll get spots in the middle of each void where you can see the sealer pooled but it should still work out.
Before and mid glass, luckily got a fiance who is stoked to help out. Adding 1 single 4 oz layer to start, and then will span the top side with tissue paper.
I too got some blobs from the concrete sealer. Not a big deal functionally, but aesthetically not my favorite. I think a proper mister rather than spray bottle could help.
I’m pretty torn right now, but pretty sure gonna go with a layer of printed cotton fabric + another 4 oz on the bottom. My thoughts are the fabric being a tighter weave could help puncture resistance. Also, will help hide those pesky little blobs.
The other option is going to be acrylic painting both sides. I know I’m gonna paint the rails, but I was thinking some art done in acrylic could be cool. The goal with either that or the fabric would be to make the board translucent kind of like stained glass which I think would be really cool.
Looks like its really coming together! I found one layer of 6oz and 4oz on both the top and bottom was about right for the strength I was looking for but your voids are larger and your board is much longer so YMMV. Never tried cotton but interested to hear how that goes! I personally wouldn’t want to paint the top and bottom to let as much of the uniqueness of the printed lattice show through as possible… maybe tinting the resin will get you the color you’re looking for without covering up the lattice too much? Something to consider.
I’m not super stoked on the aesthetics of the lattice TBH. White filament that has some dirty marks as it’s been processed and the tissue paper drips. Stuff you don’t notice from 10 ft away, but I’m a perfectionist so it’s tough to swallow knowing I could do better
I think there are likely better ways to tighten and seal your tissue before adding resin.
But if you want to improve puncture resistance, Kevlar/aramid cloth could be applied directly to the treated tissue as your first layer of laminate composite cloth. That overlayed with FG cloth, might be a good way to do that.
Using Kevlar is tricky. In oral tradition, a skimboard builder passed on his secret sauce to me. And I have a method that needs to be tested that would not require vac-bagging.
Several test panels would likely be need to perfect the technique.
More later…
Good call. Looks like it needs a really full cure to not cause issues. I’ll probably leave it for a week or two and work on some other stuff then glass to make sure it’s good
My approach would be to tighten/shrink the tissue with water only.
Then if you use Behr concrete sealer, apply a very “thin coat” with a foam pad to the pre-shrunk tissue and allow to dry — policing for drips underneath. I like Meguiars foam applicator pads (used for car wax) to apply a thin coat of Behr sealer.
However, for me personally, I would experiment with applying Behr “water-based Spar Urethane” directly to “water-tightened” tissue.
Then I would laminate directly to that Spar Urethane sealed tissue once urethane coat has thoroughly dried.
Water-based urethane finish should not have any issues when using epoxy.
Do test panels first though. My $0.02 on how I would do it.
That certainly sounds like a good method, I’ve been kind of throwing things together quite erratically. The only note I would make is that even if you water tighten the tissue, it will sag again as soon as you add another round of moisture. So the brush might puncture the tissue if not gentle
Yes, as with Guillow balsa and tissue model airplanes, the tissue sags and tightens twice. First with the water, then with colored airplane dope.
However, the method I described would use the Mequiars foam pads, not brushes, to apply water-based sealer (concrete sealer or Spar Urethane) — adding a “thin coat” to the tissue. If done softly/gently, puncturing should be unlikely.
Practice test panels, test panels, test panels…
As things have progressed I’ve gotten more risky trying things without testing first.
Shoutout to stoneburner for the suggestions. I decided not to do the enamel after all, for fear of epoxy compatibility and potential delam.
Today was a nice misting morning, so I took the board outside for a nature water tightening. Worked perfectly.
After drying, I sprayed 50/50 concrete sealer like last time out of a spray bottle, but then ran a sponge brush across to absorb the excess. Using medium pressure, it worked perfectly and with some level of caution, not prone to puncture.
There were a few spots that puddled up too long and had a drip formed on the other side of the tissue paper, which certainly would have formed the dreaded yellow bead. My solution was to tear dry chunks of the foam brush and place them on top. After a minute they had completely absorbed up through the other side. 10/10 success.
Now the top can be glassed as well. I only have one 4 oz on the bottom so far. I will add two 4 oz on the top and at least 1 more on the bottom. Since there is no stringer there is a good amount of flex still. I’m going to double, possibly triple wrap the rails in hopes of it being stiff enough.
The glassing approach “I” would use for stringerless is a symmetrical schedule. However, for me, I like symmetrical on any type of board ( surf, skate, skim, etc.)
If, I am forced to do my own glassing on my stringerless 5’6” EPS Coanda Channel board I will do 6/4 top and 6/4 bottom.
I agree with Gene and a professional snowboard builder on this.
That’s probably the best call. The weight is already beginning to get up there, and that’s without fin plugs or anything else yet. 6 oz will probably be a better choice in the end
