unexpanded kraft paper honeycomb

[Steve W]

I'm trying to find a source for the above. This is the honeycomb before it is expanded out to make a sheet.

 

[upchurchmr]

At one time Gougeon Brothers built multihulls using paper honeycomb.
Perhaps they would have a source.

Why?

 

[Steve W]

As far as I know they used verticell or tricell like everyone else who uses paper honeycomb does. Typically phenolic resin coated and this is great product and very reasonably priced when compared to any other lightweight core material. Not something you would use for a hull but for furniture bulkheads etc. I have been using pp honeycomb for making up sheetgoods because I can get it easily but it is not particularly light. I would rather use foam but you pay a lot to ship any sheetgoods regardless of weight and the same goes for paper honeycomb so it seems to me that if I could buy it unexpanded it would take up less space and cost less for shipping. I think it would need to be raw. Doing a google search it looks like it can be purchased in block or slice form but I can't find where.

 

[upchurchmr]

Well don't bother asking them then.

 

[Mr Efficiency]

Door manufacture uses that kind of thing. Not sure where sourced.

 

[Steve W]

Thanks for the thought ME,
Unfortunatly honeycomb as used in composite panels has a much smaller cell structure than the door industry uses, I buy damaged hollow core doors to use as lightweight temporary portable workbenches, nice and stiff, just throw it on a couple of folding sawhorses and cheap. Usually they are punctured on one side so you can see the core and they are a much larger cell than I would want. What I would like to find would be 1/2" cell size or less. Tricell for example have 1/4", 3/8" and 1/2". Obviously the larger cell sizes have less material so are lighter/ft3. Probably 40 years ago multihull designer Malcolm Tennant in NZ told me he was buying it unexpanded. I'm really just interested in experimenting with the idea. We pay a lot of money to ship air when we buy 4x8 sheets of lightweight core material. It weighs nothing but has to come by truck.

 

[Steve W]

Well don't bother asking them then.

Sorry, not dismissing the idea, you are right, i will contact them. I know they used Verticel on the deck and presumably furniture of Rogue Wave back in the day. Unfortunatly Meade and Jan are not with us now, I bet they would know.

 

[upchurchmr]

Have you watched honeycomb being expanded?
I saw some Ti core being done. Looked like some effort to get it even, they made a pair of special jigs. Looked like a comb set vertically with a tooth or peg for each cell on each end, pulled with a small winch.

 

[Mr Efficiency]

Thanks for the thought ME,
Unfortunatly honeycomb as used in composite panels has a much smaller cell structure than the door industry uses, I buy damaged hollow core doors to use as lightweight temporary portable workbenches, nice and stiff, just throw it on a couple of folding sawhorses and cheap. Usually they are punctured on one side so you can see the core and they are a much larger cell than I would want. What I would like to find would be 1/2" cell size or less. Tricell for example have 1/4", 3/8" and 1/2". Obviously the larger cell sizes have less material so are lighter/ft3. Probably 40 years ago multihull designer Malcolm Tennant in NZ told me he was buying it unexpanded. I'm really just interested in experimenting with the idea. We pay a lot of money to ship air when we buy 4x8 sheets of lightweight core material. It weighs nothing but has to come by truck.

There may be a variety of sizes made by whoever makes it for the door people, but I also wonder about how you would expand it without dramas of having it recoil while you were waiting for the glue to take.

 

[upchurchmr]

Typically when you expand core, you pull it farther than it takes to get it to the final dimensions, so that when you allow it to relax, it is where it is wanted. If it didn't get to the dimension, you pull again.

 

[rxcomposite]

Steve- From my book, this is how the honeycomb is made. Even if you are able to obtain the unexpanded variety and manage to make an expansion jig, you will need gallons and gallons of phenolic resin to fully immerse it. Not practical.

 

[Steve W]

I have not seen it being expanded but it can not be rocket science, I can figure it out. To be clear, this is not something I would use for major structural stuff, just lightweight furniture panels so it may not need to be impregnated at all. Tricel for example sells sheets raw or phenolic impregnated, the stuff inside any hollow core doors i've seen inside of is raw. If i was to impregnate it i would maybe use a thin epoxy instead of phenolic. I have used lots of this over the years and it has a viscosity not much more than water. It may or may not be worth while but without researching it how would i know? The only reason i am even thinking of this is the high cost of shipping lightweight sheet goods. Its always a problem, if i want a couple of sheets of any material that i can't buy locally be it bs1088 plywood, h80 foam or honeycomb the shipping is a lot and in the case of the honeycomb possibly more than the product cost. Placing a big order works out better per unit but that's not always possible cost wise. I have used quite a but of pp honeycomb which is readily available for me but its heavy, i was told it was 5lb/ft 3, same as h80 foam but it has always felt a bit heavy so i weighed a piece and it worked out to be around 6.4lbs/ft 3, ouch. Which is why i'm looking at paper again.

 

[rxcomposite]

We used a lot of honeycombs and it comes in varying grades/weight. The heavier ones does not seem to be thicker in base material. Just a heavier coating of phenolic. Maybe it was dipped twice or just used a lower viscosity. We even used aluminum honeycomb cores and there is no coating in it. You can try to experiment either by using a stiffer material or a soft material and reinforce it with resin.

 

[Steve W]

We did a whole interior on an 81 ft maxi 40 years ago with F board aluminum honeycomb but it came to us in sheet form with skins, I'm not sure how they bonded the skins though, with the pp honeycomb they thermally fuse remay to it otherwise I don't think you would get a good bond.

 

[rxcomposite]

Bonding honeycomb is always a problem. When we were using the vacuum method/sheet glue/high temp curing, trapped air in the cells would cause it to expand during the melt process. When it cools down, there are pockets the size of golf balls that did not bond.

With the cold process, we have to prime the edges of the honeycomb with resin and coat the skin with slightly thickened resin before bonding it. Bonding was done using low pressure/vac bag or sandbags.

The idea was to have a glue fillet that runs up to the edge of the honeycomb web forming a very strong and consistent bond. We did not have time to experiment with the proper viscosity of the resin for a consistent bond. We were cutting the panel into sections to find how well the glue ran up to the honeycomb web to form a fillet.