I was toying with the idea of making a couple of board bows with a fiberglass backing. Just to be clear, I'm not talking about a typical modern laminated glass bow with glass on both back and belly. Essentially, I'm talking about a would be self-bow except with a fiberglass backing. I'm wondering if this would actually work? I'm thinking that I could still tiller it the way that I'm use to doing but hoping the fiberglass will prevent it from taking much set. Also wondering about it being slightly more durable? Will it also help as a backing for a board that is not perfect (but close to perfect)? What woods would work better and what woods would not work so well? If anyone has any feedback or thoughts I would really appreciate it. Also curious if anyone knows if that is how Fred Bear first started using fiberglass on bows?
P.S. For the all-natural material purists, I'm well aware that there might be more "natural" ways to do this, but I'm curious about fiberglass specifically. lol Sorry.
I'm no expert, but I don't see why a thin layer of glass over a compression strong wood like ipe wouldn't work.
there are bowyers here who are way more knowledgeable though and I would take their advice.
Just curious, where in Canada are you?
Dave.
I'm in London, Ontario. How about you?
1 hour east in Cambridge. I was curious because I know another David Wood who has an automotive shop near my place. Nice to know there's another bow builder nearby.
Dave.
Are you talking about using standard bow-building glass laminations? Certainly should work.Self bows backed with epoxied fiberglass drywall tape is 'old school' self bow technology...
Sam Harper has used fiberglass backing. I'm sure it works just fine.
I think he has some youtube videos.
Jawge
I have made one like this, but it was a light weight bow (35-40#s) It worked, but I suppose the key is to ensure a compression strong wood is selected.
Yeah I mean the main risk is that you put too much stress on the belly wood and you get compression fracture on the belly.
Would I wanna do it with red oak? probably not ... Would I try it with Ipe? Why not, if any wood has a chance against fiberglass it's ipe.
Fiberglass will however cause MORE set not less.
Set is a result mainly of permanent compression of the belly side, not stretching of the backing, although that probably contributes a bit too.
I think you are going to get more set using fiberglass.
The way to reduce set is to build the bow at a proper width and to match the tension strength of the backign to the compression strength of the belly.
Bamboo backed Ipe will give you very little set if it is designed properly ..... for that matter so will unbacked poplar, it's just going to need to be 2x as wide as the bamboo backed ipe.
Why don't you give us some idea of the type of bow and draw weight and draw length that you desire, and then you can get some input on what a proper design might be.
Hope that helps!
A couple of commercial bowyers tried this a few years ago and realized it didn't work as expected. The glass backings overpowered the bellies in some cases.
There is no need to use FG backing on a selfbow. There are other more appropriate backings that have been proven over the years or centuries and a well made selfbow shouldn't need a backing of any kind.
The best way to control set is to tiller properly without overstressing the bow.
Well my plan was to try make an American Flatbow style bow out of red oak (or maybe ash) and back it with automotive fiberglass. From the sounds of this thread, it might not work as well. I was trying to use materials that are easy for to find. The main reason I thought of it was in the interest of making a bow with a handle that is closer to centershot. I was also curious about when they talk about silk backing (in case the red oak board is not quite perfect) what kind of silk are they talking about? I went to Fabricland and all they had was material for silk drapes. Is there any other cloth or fabric material that will work as well? Do you glue these on with titebond 3?
+1 Patb...sound sage wisdom there
For a wood belly either use rawhide if your just concerned protecting the back,or use a properly selected and matched piece of wood or boo that matches well in tension compared to the strength of the wood that will be used in compression(belly). And if your new to tillering wooden bows then keep it as simple as possible without all the glues and hard backings(rawhide or the likes OK),and learn how to tiller.....it takes most folks several to a couple dozen bows and attempts before they really get the hang of it....
You posted right before I did....yes silk will work and titebond glues are just fine....and you can make natural bows close to center shot or with a cut out shelf if done properly(key words)
Don't worry about whether it will work or not. Just try it. Report back on the results.
Here's how I would proceed. Make sure and stretch the cloth to find out which direction stretches less and lay it down like that. Then bend some reflex into the bow and stretch the cloth as you lay it down. You may get some tension work out of it that way.
Dave,
Flatbows are pretty safe as long as the back has straight grain. No backing is really needed, but as the blackmockingbird said, rawhide isn't a bad idea.
Personally instead of buying 1 board, 1 piece of fiberglass and one pint of resin to apply it, I'd probably just buy 3 boards.
Red oak is actually pretty strong in tension, it can back other woods and works just fine unbacked. Just look for straight grain and no pin knots on the back.
I backed an ash with autobody fiberglass when I was really new to bow building. Half way through tillering and the top limb exploded.
If you want to make a selfbow centershot just leave enough wood in the riser so it doesn't bend. It's the grain lifting due to flex in the sight window that causes failure, but enough folks do it that it's possible. A backing won't really help a whole lot there, unless it's something like boo or hickory. Again though, enough folks make it work that there's no reason you couldn't too.
I have made a few board bows and backed with fiberglass. I have used Hickory and Osage. Ordered fiberglass from 3 rivers. The bow I shoot came out at #55 at 28". I think it shoots well.
I did a red oak 35 pounds. Used fibreglass cloth to back but instead of epoxy I used plain old wood glue. Worked good but burlap would work and look about the same and be cheaper. The only reason I used it cause it was in a bargain bin in nice ready to go strips haha.
I have experimented with fiberglass and formica as backings on dozens of bows, the glass worked great till the wood failed and eventually they will all fail. The formica worked great until the formica broke after a few hundred shots. This was over maybe a ten year peroid. Finnaly gave up and I build only all glass bows now.
I did a quartet of oak pyramid bows backed with automotive fiberglass, paper bag, rawhide and cotton duck. Was not for performance but simply for protection. All worked fine and all four are still shooting.
Could not see any performance added increment in the glass, duck or rawhide. If anything, any performance inherent in the backs was more than stolen back by their weight. The paper bag perfomed the best and was the easiest and most economical to apply.
Given the light weight of silk, it would probably work out right alongside the paper bag.