I need to put a foil box into a board, how do I do it?

[Califoilia]

Shark, for myself, "a picture's worth a thousand words", so here's Dave Daum of King's Paddle Sports putting in his own "King Tut" box with Gorilla glue, and a spray bottle of water....
https://www.youtube.com/watch?v=M7v4pEgQrZg
Notice that he has way more than 60 seconds of positioning time in the clip...and he's got quite a number of foil boards out there now, and to my knowledge, has not had a single box failure as of yet (hope that doesn't jinx him now ).

Here's the cameraman above, and that board in that in action from yesterday...
https://www.youtube.com/watch?v=KVQuCXMVNs8
(Shoutout to "StandinDan" for the aerial footage).

[PonoBill]

You don't have to do the premix with a large surface area, tight fit like yours. Just butter the parts with gorilla glue. Then use a spray bottle to soak the Gorilla Glue down with water and put the parts together. That way you have at least ten minutes to play around and get the fit perfect.

[sharksupper]

Ah!  This is the bit I was missing.  I thought you had to mix the water in with it so it foamed up right.  Awesome, I might just be able to do this after all.  I'm just going to run one more shear strength test with epoxy vs gorilla glue to solidify my understanding of how it's going to work and then if all goes well have at it!  Thanks guys!

[sharksupper]

Not that this video applies to what I'm doing, interesting none the less:  https://woodgears.ca/joint_strength/gorilla_glue.html

I would imagine that as the gorilla glue foam gets thicker (between the parts it's gluing) it's shear strength reduces significantly. 

In the case of gluing foam, I'm sure it's less of an issue though, since the foam is relatively weak already.

Just to prove this for myself I want to glue two pieces of XPS together with a 1/16" gap using both Gorilla Glue and thickened Epoxy and see which has a high shear strength.  My thought and hope would be the Gorilla Glue, but I just want to see if it's stronger than the XPS once it's filling a gap as wide as 1/16".. which is about the average gap I have to fill... some parts less some parts more.

[Beasho]

My thought and hope would be the Gorilla Glue, but I just want to see if it's stronger than the XPS once it's filling a gap as wide as 1/16".. which is about the average gap I have to fill... some parts less some parts more.

The Gorilla Glue doesn't have to be stronger than the XPS for the last 1/16" just stronger than the EPS.  Eventually all the load is going to the EPS who cares about the final 1/16". 

Just to pile on: Less moisture will kick slower.  Raw gorilla glue will dry well against EPS with just a few topical sprays.

I put my box in yesterday and had ~15 minutes to work with.   

[opie]

Out of Divinycel, had to buy a sheet. Where are you getting it for $100?

I've never actually bought any, it just seemed from quick guessing while looking at the Fiberglast website that about 100 dollars worth would end up in my board if I went that route.

[PonoBill]

Out of Divinycel, had to buy a sheet. Where are you getting it for $100?

I've never actually bought any, it just seemed from quick guessing while looking at the Fiberglast website that about 100 dollars worth would end up in my board if I went that route.

You can spend a hundred bucks in a hurry on Divynicell. I generally buy it in 1/2" X 32" X 48" sheets and layer it. I think I pay about 60 bucks each for quantity five or ten. My memory sucks.

[sharksupper]

Ok, so I've been stalled on getting the box in the board.  Lots of wind, too cold for epoxy, nothing but excuses! 

I was 90% ready to go with the Gorilla Glue, but my final affirmation test, which I expected to go without any surprises, had an interesting twist!

I very coarsely (with an 80 grit sponge) sanded XPS on two opposite mating sides and then used balsa wood a few inches apart at 1/16" thick to see how both Gorilla Glue and Epoxy faired in a balance of both bonding strength and gap filling together... as is the case with putting in my cassette.  I basically just wanted to see if the awesome bonding characteristics of Gorilla Glue still held true when gapped out a little bit.  I actually did this test pretty methodically.  Both pieces had a 3" square mating surface, everything was the same.  I used a very thick lather of Gorilla Glue (roughly a tablespoon each) on both surfaces, pressing it into the surfaces hard with my fingers and then sprayed it once really good with water on both sides.  On the epoxy front I mixed it much thicker with microballoons than I ever had before, by accident.  I really thought I was wasting my time with this test because at first the epoxy was so thick with microballoons it actually wouldn't even stick to the foam!  It was the thickness of those peanut butters than almost bend your butter knife trying to mix!  I actually broke a 1" tongue depressor just trying to mix it.  I ended up having to really work it into the foam with my finger tips until it finally penetrated and held some surface tension... then I just flooded the gap with a pile and squished the XPS together.  I was also testing to see if the epoxy would melt the XPS in this test.

The Gorilla Glue foamed up and outside of the gap as expected within 3-5min.  I let everything sit for several hours and then tried to pry the pieces apart from the sides.  I did not slice into the Gorilla Glue gap with anything like that, I wanted it to naturally fail when being pulled directly apart.  When it did, to my huge surprise, most of the Gorilla Glue "foam" in the gap had failed before the XPS!  I am really shocked at this result, but that's what happened.  You can see in the picture how a few small places let go on the XPS on either side, but most of it gave way within the Gorilla Glue foam gap itself.  I also didn't twist this piece to break it, I literally pried it from the unglued end until something broke.

Despite this result, I still thought the epoxy had probably done worse.  Again, another surprise!  The XPS broke first in about a half inch thickness above the epoxy layer!  I wish I had snapped the pic before I further destroyed the piece, but I wasn't expecting to have to take pictures of this test, I thought I knew what the result would be.  Even though the epoxy worked well, had to do over again, I would use some unthickened epoxy and spread it thinly around the surfaces for penetration first, then fill the rest in with the thickened stuff.

I don't know what to say, the Gorilla Glue seems to have great bonding strength when there is no gap, but leaving a gap allowing it to foam up between seems to be much weaker.  This test was done with very dense XPS, so on EPS it's probably not going to fail first, but still interesting to learn this glues properties, what it's good at and what it's not as good at.

My XPS didn't melt, and the Gorilla Glue didn't hold as well, so I'm going with the epoxy based on my testing results, not because that's what I've always done (I've never done this before, first time!  )

[surfcowboy]

Couple of notes.

Edubz is using divinycel the pour foam is replacing the epoxy or glue.

Second, I'm not sure that a "few hours" is enough for a PU glue. Most say 24 hours til full strength but you do you man. It'll be fine. There's a lot more foil mounts working out there than breaking.

[PonoBill]

Cool, maybe there's something new to learn there.

[eDUBz]

Out of Divinycel, had to buy a sheet. Where are you getting it for $100?

I've never actually bought any, it just seemed from quick guessing while looking at the Fiberglast website that about 100 dollars worth would end up in my board if I went that route.

You can spend a hundred bucks in a hurry on Divynicell. I generally buy it in 1/2" X 32" X 48" sheets and layer it. I think I pay about 60 bucks each for quantity five or ten. My memory sucks.

I know, I get mine for $140

[eDUBz]

Couple of notes.

Edubz is using divinycel the pour foam is replacing the epoxy or glue.

Second, I'm not sure that a "few hours" is enough for a PU glue. Most say 24 hours til full strength but you do you man. It'll be fine. There's a lot more foil mounts working out there than breaking.

Yes, divinycel block. I’ll make the block first and use the 2 part PU foam to set it. I’ll that cure and come back and install the mast tracks.

[Newps]

Ok, so I've been stalled on getting the box in the board.  Lots of wind, too cold for epoxy, nothing but excuses! 

I was 90% ready to go with the Gorilla Glue, but my final affirmation test, which I expected to go without any surprises, had an interesting twist!

I very coarsely (with an 80 grit sponge) sanded XPS on two opposite mating sides and then used balsa wood a few inches apart at 1/16" thick to see how both Gorilla Glue and Epoxy faired in a balance of both bonding strength and gap filling together... as is the case with putting in my cassette.  I basically just wanted to see if the awesome bonding characteristics of Gorilla Glue still held true when gapped out a little bit.  I actually did this test pretty methodically.  Both pieces had a 3" square mating surface, everything was the same.  I used a very thick lather of Gorilla Glue (roughly a tablespoon each) on both surfaces, pressing it into the surfaces hard with my fingers and then sprayed it once really good with water on both sides.  On the epoxy front I mixed it much thicker with microballoons than I ever had before, by accident.  I really thought I was wasting my time with this test because at first the epoxy was so thick with microballoons it actually wouldn't even stick to the foam!  It was the thickness of those peanut butters than almost bend your butter knife trying to mix!  I actually broke a 1" tongue depressor just trying to mix it.  I ended up having to really work it into the foam with my finger tips until it finally penetrated and held some surface tension... then I just flooded the gap with a pile and squished the XPS together.  I was also testing to see if the epoxy would melt the XPS in this test.

The Gorilla Glue foamed up and outside of the gap as expected within 3-5min.  I let everything sit for several hours and then tried to pry the pieces apart from the sides.  I did not slice into the Gorilla Glue gap with anything like that, I wanted it to naturally fail when being pulled directly apart.  When it did, to my huge surprise, most of the Gorilla Glue "foam" in the gap had failed before the XPS!  I am really shocked at this result, but that's what happened.  You can see in the picture how a few small places let go on the XPS on either side, but most of it gave way within the Gorilla Glue foam gap itself.  I also didn't twist this piece to break it, I literally pried it from the unglued end until something broke.

Despite this result, I still thought the epoxy had probably done worse.  Again, another surprise!  The XPS broke first in about a half inch thickness above the epoxy layer!  I wish I had snapped the pic before I further destroyed the piece, but I wasn't expecting to have to take pictures of this test, I thought I knew what the result would be.  Even though the epoxy worked well, had to do over again, I would use some unthickened epoxy and spread it thinly around the surfaces for penetration first, then fill the rest in with the thickened stuff.

I don't know what to say, the Gorilla Glue seems to have great bonding strength when there is no gap, but leaving a gap allowing it to foam up between seems to be much weaker.  This test was done with very dense XPS, so on EPS it's probably not going to fail first, but still interesting to learn this glues properties, what it's good at and what it's not as good at.

My XPS didn't melt, and the Gorilla Glue didn't hold as well, so I'm going with the epoxy based on my testing results, not because that's what I've always done (I've never done this before, first time!  )

Seems like this test was seriously flawed.  You mixed the epoxy to an unusable thickness.  I am guessing you added too more curing agent then the 50/50 ratio?  More curing agent will speed up the curing time.   You also did the did not let the Gorilla Glue enough time to bond and cure which is 24 hours. 

I am not trying to persuade you to use Gorilla Glue.  However others may read this and be influenced by this test. 

[sharksupper]

Yea, who knows.  I waited until the epoxy was hard, about 10-14hrs.  Both were hard as a rock.   Epoxy was mixed 5:1 to the nearest 0.01g, no mistake there.  I just added too much microballoon to the mixture and it was a bit thick.

The test isn't exact, no, but it was enough to show me the Gorilla Glue looses most of it's strength when there is a gap (versus no gap, like in my first test).  In this test it was 1/16" gap.  The foaming action of the glue put so much air into the gap that very little glue was actually adhering the two surfaces being glued.  The density of the foam was all over the place, some huge bubbles 1/2 wide in places where there was no glue connecting hardly at all.  It wasn't because I didn't put enough in there, it foamed out all over the place on the sides.  All this could just be how you use it, I just might not have the technique down.  I would never make any recommendation off just one of my limited tests/experiences, so please, if you're reading this, go do your own practice tests and see what works best for you, that's all I did here.  Just sharing the outcome so you understand why I made the choices I did.

In the end it would have been fatal to the project if I had gone with the Gorilla Glue... I took the full 1-2hr working time with the epoxy to get the box put in with proper alignment, I was so happy I had all that working time!  I worked near the minimum temp of the epoxy and thermals never got about 78F.  Currently curing...

[sharksupper]

I pulled all the masking off just before it got too hard for easier clean up later.

I kept the box recessed just a bit below the bottom surface of the board to allow sanding of the surrounding board surface to take the laminates.

I was planning on 3-4 layers of carbon and maybe one glass sanding/anti-pinhole layer per side.  I was thinking each layer would go 3/4" to 1" wider than the box/the previous layer on all sides.  Maybe angle the front and back cuts so it doesn't create a straight across the board stress point.

Any suggestions?