Question for any Engineers or Materials Scientists out there

[Shredd]

Yeah...  That's a wee bit up there, isn't it...  Well you are welcome for a visit in sunny Florida to escape some of that winter...  I'll even spot you a few strips of formica...   

[Mad Max]

I've noticed alot of people on the book that make board bows, live out in the boonies.
No Osage in other country's, mostly

[onetone]

And it is always best to not get too full of oneself ...

[flyonline]

Steve, uni fabrics would no doubt  work, just not for what I am doing. Mine is not an open lay-up, so clamps are not an option. I have been trying to as closely as possible mimic the process used by manufactures, pultrusion, to make my composites. The main issues with an open lay-up are fabric saturation, surface finish and excess resin content, which is why I have started doing a resin infusion process. Do a search on that subject and you will see what I mean.

I'm aware how infusion works, and even tried a couple of crude experiments myself but I don't see why you couldn't use uni fabric, or use clamps to tension the carbon. It would be a fair whack of work and you'd have to build a specific mold and the way I was thinking there would be a lot of waste.

I'd like to hear anybody's ideas

Have you come across foaming agents for resin? I know guys have used it to build RC gliders to reduce resin weights (e.g. https://www.rcgroups.com/forums/showthread.php?1842115-Foaming-agent-epoxy), I understand you need to be careful with heat though 

[mmattockx]

Ha ha ha ha...  Mattox...  That is the funniest thing I heard all week... You, build the bow and prove me wrong...       I already said that I did mock ups with it and I know how tuff it is... 

In my world doing a mock up isn't the same as making the bow. I wasn't looking for a fight, I would genuinely like to see that. Cheap and effective are always a good thing in my book. Any info on calculating stack for one of these?

Look at where he lives, may not be alot to choose from or shipping eats him up shredd

This is true. Good bow wood is very thin on the ground here. I like working with wood but may eventually end up doing a lot of fibreglass bows just because the wood I have available is not great. If I had good supplies of osage, yew or juniper I probably wouldn't worry much about fibreglass but that isn't the case.

Yeah...  That's a wee bit up there, isn't it...  Well you are welcome for a visit in sunny Florida to escape some of that winter...  I'll even spot you a few strips of formica...   

Someday, who knows? It could be a formica bow building retreat.


Mark

[Shredd]

  Formica build retreat...  Sounds good to me...

   Got no idea on stack...  No fight here... You might have read me wrong...

   I have used it instead of glass to see what the springback would be on an experimental prestress limb project...   I had to really stress that limb to break it... Way more than wood would have handled...

[Flem]

Steve, uni fabric could certainly work. But you hit on the drawbacks in the next sentence.
I've seen foaming agents, but I'm thinking they will weaken the matrix. Right now I am having a hard time sourcing the hollow glass spheres I want. All I can find for sale are the ones with low crushing strength.
The ones with a crushing strength of 18,000psi or higher are not readily available.

[Shredd]

They are available...  I found it before...

[Flem]

They are available...  I found it before...

Care to share where you found them and if they are still available from your source?

[Shredd]

I don't know...  it was a few years ago...  I looked but I did not save the site... 

[Flem]

I've been looking real hard and have not found any that I would use. I have found lots of 3M K1, K20 and some S32 spheres. But they have crush strength of 250psi, 500psi and 2000psi. The ones I am trying to source are 16,000psi on the low end and 27,000 for the primo ones.
Thats like comparing Balsa wood to Ebony and thats not even accurate because Balsa is closer to S32 and no wood comes close to 27,000 psi crush strength.

[Shredd]

Here is a link...  19,000  psi

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Glass-Bubbles-HGS19K46/?N=5002385+8745513+3292737335&preselect=8710783&rt=rud v

[Flem]

Thanks, I already have downloaded all of 3M's literature on HGM. Thats not a retail site you linked to.
3M does not sell in small quantities to you and me. Maybe if you were looking for a semi load...

[Shredd]

   I know... Call 3m for a distributer of the product you want...   

[Flem]

I have contacted 3M and put in a request for samples and sources, but not heard back from them yet.
Calling might be a good idea  

[williwaw]

I am definetly going to make both these experimental composites.

are the bubbles you are trying to source for the lam experiment or the core experiment? The stresses would not be as extreme for a core materiel.

[Flem]

You must be confusing me with the guy doing the core experiment.

[Stagmitis]

Whatcha think Shreddy?  You can see the dark area on the belly lam compared to the back glass.....

[Shredd]

   WoW...!!!  You just blew my mind...  Not only formica but the design you would see in every old diner from here to California...  That's crazy...   I believe you got yo'self a collectors item...

[Stagmitis]

Lol even Byron signed it