Foam Cores

[Nicholi]

Is anyone using foam cores? I would like to try it but I am having a heck of a time locating the right syntactic foam. The only thing I can find for archery is that Dale Stahl used to sell it. Are bowyers making their own? If so, does anyone have any tips?

Any ideas?

[Kirkll]

I bought my foam from Dale Stahl years ago, and built a few sets here and there using carbon backing. I have no idea where you could purchase it now.

Tricky stuff to work with. very fragile and the finished product produces a very weird sounding bow. Kind of a tinny sound. Dale used to mill it and sell strips, and it was expensive.

The foam fad kind of faded away due to a number of reasons. Longevity of finished product was always in question, and disadvantages and cost outweighed any gains in performance using the light weight foam.

When pushing them to their limits, it’s the only limb I ever saw blow up in that many pieces. Two inch pieces of limbs flying all over the shop. 

  I sure wish I still had those video clips I took of blowing up limbs intentionally. It was entertaining. When we were prototyping limbs and had a failure, we would film the second limb while stressing it until it blew up to see where it let loose first and find the weak spot.

Good luck my friend. If you do find some, be careful. It’s touchy stuff.    Kirk

[mmattockx]

The foam fad kind of faded away due to a number of reasons.

This may be true for small volume custom bowyers, but both foam cores and all carbon lams are the go to in high end recurve target archery equipment. You would be hard pressed to find anything other than carbon/foam limbs on a shooting line in international level competition.

I don't doubt that foam cores can be a problem for custom makers, but they seem to work very well in a production environment.


Mark

[Shredd]

Nich...  What are you hoping to achieve by using foam cores??

[Nicholi]

Shredd, a few things. Consistency, which I know I can get with spectraply or even maple really. Humidity/temperature stability. The big one is that the big dogs have it worked out, why can't I?

[Nicholi]

Kirk, its too bad you don't have those videos!

I don't see it going away either. If anything I'm seeing more of it. I will be careful though.

[Jeff tech]

I had 4 foam cores giving to me .I only put 2 foam cores in and 2 maple. It did have a increase in speed. Put to me it has no soul. JF

[Kirkll]

Well the big dogs building these 100% composite limbs have resources that us small time bowyers do not have. That and they probably manufacture their own product including the foam/carbon components, and have a production line.

I’m just sharing the experience I had with the stuff and my own opinion . Take it for what it’s worth to you.

Good luck getting the consistency you are looking for. It’s only going to be as consistent as the backing you use.    Kirk

[Shredd]

You could buy some micro-balloons and epoxy and make your own...  Possibly even add some chopped glass fibers to toughen it up...

[mmattockx]

I’m just sharing the experience I had with the stuff and my own opinion . Take it for what it’s worth to you.

That's fair and it is often the case that methods that work well in volume production are unsuitable for small batch work and for the home size shop where you don't have the big machines and equipment to work the high volume methods.

TBH, I would prefer wood cores from a custom bowyer. Wood offers more character and performs extremely well if done right.


Mark

[Kirkll]

I’m just sharing the experience I had with the stuff and my own opinion . Take it for what it’s worth to you.

That's fair and it is often the case that methods that work well in volume production are unsuitable for small batch work and for the home size shop where you don't have the big machines and equipment to work the high volume methods.

TBH, I would prefer wood cores from a custom bowyer. Wood offers more character and performs extremely well if done right.


Mark

You got it bro…. Same thing applies to building carbon backed bows. Buying the stuff in volume and mass producing limbs is the only way to get consistency. It’s a nightmare just building a few here and there and hitting draw weight consistently.
It’s bad enough for the little guy getting different shipments of glass. But at least you can sand glass to adjust things.   Kirk

[Nicholi]

It sounds like I have my work cut out for me! I'll do some experimenting and post whatever I wind up doing.

There's gotta be a way for us little guys to do this successfully.

[Robertfishes]

Kirk, thanks for sharing your experience with us. I can see you put a lot of time, effort, money and likely lost some blood...into trying the foam core work for your designs.
I wanted to try some out 10 years or more ago but the guy selling it ((Old Master Crafter) talked me out of it. He knew I was a hobby builder and did not have time or resources to really make it work correctly. Meaning Building, testing and tweaking multiple forms to get best performance out of the limbs.. My wife shoots a Olympic style bow quite often.. She prefers foam core under glass limbs for her Olympic ILF bow.

[Longcruise]

The last owner of Old Master Crafters (Jim Belcher) now owns Bivouac Bows and may have some of that foam laying around.

https://bivouacbowco.com/

[kennym]

Jim Belcher has retired, he called and offered to sell me some of his equipment...

He might have stuff left tho.

[Kirkll]

Kirk, thanks for sharing your experience with us. I can see you put a lot of time, effort, money and likely lost some blood...into trying the foam core work for your designs.
I wanted to try some out 10 years or more ago but the guy selling it ((Old Master Crafter) talked me out of it. He knew I was a hobby builder and did not have time or resources to really make it work correctly. Meaning Building, testing and tweaking multiple forms to get best performance out of the limbs.. My wife shoots a Olympic style bow quite often.. She prefers foam core under glass limbs for her Olympic ILF bow.

No blood lost, but definitely had some fireworks a few times. I had a set of double carbon foam core limbs let go at a full 30” draw one time, and both limbs blew at the same time. No injuries, but I needed a clean pair of shorts.

There is no doubt you can build seriously light mass weight limbs using the stuff which naturally increases performance. But you need to be very careful pushing the envelope of your limb designs draw length capacity. If you force that foam to compress to much, it explodes. I always used a thin maple lam on the belly side next to the carbon or even glass to insure the compression didn’t overload the foam. Even Border bows used a maple lam on their belly side years ago. I have no idea what they are doing  now.

Building light weight target bows that are 64-70” length and keeping a flat string angle with minimum limb travel is going to work much  better using foam cores than heavier draw weight static tip hunting bows at 60-62” lengths and shorter limbs. I believe a lot of the target recurve limbs are working recurve design too. That would take a lot of the stress off a limb having that curl open up rather than storing all the energy in a shorter working section like the static design does.

Or this is my theory anyway. Quite honestly I never spent much time trying to develop  target grade limbs. I’ve always struggled with torsional stability on very light draw weights using a static design with a radical hook. I’d have  to build new forms with a larger radius hook and ditch the  tip wedge to pull off a working recurve.   Kirk