Laminated bow: wood types

[AlexS]

I'm new to this site, so hello everyone.=)

What I am planning to do is a longbow of around 2 meters (sorry for the calculations, I can only say it's like 6.1 feet) =). I also want it laminated (thanks God, someone here wrote about a firefighters air hose). The problem is, I have trouble choosing the material: the local stores don't offer any special bowbuilding laminations like those pretty thick slices of bamboo on the pictures. All the lams actually are 0.6 mm thick (sorry again, no suitable calculator). Clearly they are for furniture.

Still, some people manage to make bows of white ash lams. I've only heard bad things about them. So, things I can get are: maple, walnut, hickory, ash, oak, birch and some others. Bamboo is also available, but it's reconstructed and doesn't seem to be any good.

I'd be glad to see your suggestions. Well, and if somebody could help me with calculaiting the drawback weight... .

[stace]

AlexS
Mate firstly welcome to Ozbow
Next if you already havent got it grab John Clarkes book on building a Laminated Longbow also I think he sells Laminations both ground and unground
Trades under
Ausbow Industries
33 Cadell Street
GOOLWA SA 5214
Ph (08)85555888
Fax(08)85555999There is all the info you will need to get started like then RCT graphs (Reference Core Tickness for calculating draw weight)
Some of the other guys can give you more pointers in relation to building a Longbow ( Ive only built recurves as yet )
Ps the fire hose is available from The Purple Pig line of stores
And I use SMOOTH ON EPOXY EA40 from ROWE TRADING in SA
Also what State/country do you hail from this makes it easier to answer questions in relation to availablity of resources and local bowyers
stace

[Graeme K]

Hi Alexs
First welcome to the site. Great to have another budding bow builder on board.
From your questions I am guessing that you have not tried this before. I believe it would be possible to make a laminated bow using furniture veneer as the inner core material and any of the things that you listed should work but I doubt that you could use them for the back and belly lams, these need to have a lot of strength as all the loads are concentrated in them. In most laminated bows the belly and the back are a fibre glass lamination made especially for bows.
If you want to make an all timber laminated bow you have to choose the materials very carefully and the lams need to be at least 3mm thick to have enough strength above the glue line. The easiest bow of this type to make is one where the limbs are made of only 2 laminations ( a front and a back ) and some extra material for the handle. This limits how much shape you can glue into it as the laninations are very stiff. If you choose to make multiple lam wooden bows you need to have equipment to cut and grind the lams prior to glueing.
As you seem to be planing to build a former and use a hose with compressed air to clamp I am thinking that you would like to build a " Composite Long Bow " of some description. If so the easiest thing to do would be to contact Ausbow Industries in South Australia who sells wooden laminations and glass to build bows, he also has a book he publishes that tells you how to do it and how to calculate the draw weight etc.
His web site is www.ausbow.com.au and his name is John Clark.

Hope This Helps ----Graeme

Looks like Stace types a little quicker than me --- If you have any other questions just ask

[AlexS2.0]

Something went wrong with the acc registration. It's me again.

Thank you very much. I'll try to find something 3mm thick. I'm afraid, the only available would be ash. I am going to use fiberglass. Though, it's not going to be any special: odd small-pattern rowing, 3-4 layers. This should be more than enough.

Stace,

My location may seem strange. Russia, St. Petersburg. This means, there's always a possibility that the customs will do some trick if they see a delivery marked like "bow building supplies" And it's anyway going to take MUCH time for the cargo to arrive. Leave alone the price.

So, building a bow becomes some kind of sport: one has to gather data and use available materials.

Thanks again
Yours,
Alex

[stace]

AlexS
Glad your back with us at OZBOW
We have another of your countrymen on here occassionally the WILD RUSSIAN going on his profile he is in NOVOGRAD

That is why we at OZBOW are asking when you fill in your PROFILE ,you include your location as it helps in replying to your questions
WE have a member here GILNOCKIE who makes his own glass and uses Furniture VENEERS to build his bows it maybe worth a PM to him for some pointers (he is based in Tasmania )
So an A4 sized book 13mm thick TITLED BUILDING A LAMINATED LONGBOW wouldn't get through to you?
There are a few build alongs here on OZBOW on at least one longbow and you may find others at http://www.tradgang.com/?%20target=
and http://www.stickbow.com/
Hope this is some help
Stace

[AlexS2.0]

Stace,

Thanks for the info. The book will pass, the problems may occur for mats. I'll think about it.

I'll fill in the profile later, if, of course, this acc will be on tomorrow.

Best wishes,
Alex

[stace]

AlexS
You shouldn't have anymore problems in regard to LOG IN
OZBOW of late has been inundated with SPAMMERS and with few details filled in you may have been lost in the shuffle
all the best
stace

[AlexS2.0]

Stace,

Well, that is normal. Adding some details right now... I'll try to catch the person, you wrote about.

all the best,
Alex

[archangel]

Alex,

Welcome to Ozbow. You mentioned you were considering using fibreglass with random rovings as a backing. I think you will find that this material really isn't suitable for bows as the fibres need to be unidirectional ie. all going the same way down the bow. Carbon fibre cloth can be bought here but it is very expensive. Have you considered raw bamboo strips for backing? Yeoman, Greybeard, myself and several others have had very good success with this material. Do a net search here and other sites like The Leatherwall/Bowsite for build-alongs using bamboo. It should be fairly available given your proximity to Asia. regarding the laminations, ash and maple are fine (depending on species). At the end of the day, use whatever materials you can get hold of.

[AlexS2.0]

Archangel,

I didn't mean to use any random-rowing fiberglass. What is called "rowing" here is just a stronger type, which has smaller "cells" and closer weaving than normal fiberglass. I thought, this could do better than the ordinary.

And concerning the thickness of the lams. Would you still reccomend using thick laminations for the backing if I am going to use fiberglass?

All the best,
Alex

[gilnockie]

Hi Alex

I have used woven fibreglass fabric to reinforce a bow. It does not work. The woven material fails because the strands do not lie straight; they have to go over and under the other strands at 90 degrees as a part of the weaving process.

If you want to use fibreglass I strongly suggest that you buy your glass and tapered wooden laminations from a firm such as 3 Rivers Archery in America or Ausbow in Australia.

Alternately I agree with Archangel that you should use a combination of a local timber and bamboo.

[Graeme K]

Hi Alex
Now I know where you are it is easier to help you.
The guy called Glikockie on this site builds bows using .6mm furniture veneer by stacking up the layers and shortening each layer to get a taper made of steps he then hand sands the steps down to give a smooth taper. As you are going to use fiberglass on both sides this should be fine .
The fiberglass used for bows is normally a rigid lamination that you buy which is made of high strength epoxy with glass fibers that only run longitudinally. This is because only the longitudinal fibers do any work. It will work if you use woven fiberglass cloth and laminate it on to the bow but the fibers that are at right angles to the bow will not do any work, they just make the limb heavier and slower. If you use woven cloth you will need to have enough layers to have about 1.5 mm finished thickness, this will probably be 3 or 4 layers and you need to use very high strength epoxy. This is because the epoxy on the back only holds the glass on and the glass takes the tension which is easy but the glass on the belly is in compression and relies on the epoxy to hold the fibers straight to allow them to accept the compression loads.

Working out the dimensions is not a simple thing but to give you an idea -- if you build a bow that is 1800mm long with a 350mm non working handle including the fades, then I would make the limb 13mm thick at the fades and about 8mm at the tips. If you make the blank 45 mm wide to begin with then you can narrow it down to lower the weight and you should be able to get a 40 to 50 pound bow. After you have made the first one you can adjust the dimensions by knowing that if you make the bow half as wide it will be half as strong but if you make the limb half as thick you will make it one eighth as strong.

I realise that this is sort of simplistic advice but given your location and lack of availability of materials this is about the best I can do

Cheers Graeme

PS if I was going to choose one of the veneers that you mentioned then I would use Hickory as it is extremely forgiving.

I just noticed that Gilnockie said that woven cloth does not work because the weaving causes the fibers to work on one another where they pass over each other but I have found that this only happens if the epoxy is not strong enough and allows failure due to load between the fibers. I have used woven cloth with complete success but I do not suggest that it is the best answer as you can not get as high a glass to resin ratio and even if you did only half the glass would be working also the epoxy resin that is available for wet laminateing is no where as strong as what is used in the commercially available glass laminations but given your restrictions it can be made to work.
When you think about it the worst glass lamination is much stronger than any wood so it is just a matter of designing your bow to not over stress the material just as you do when using weaker woods by making the bow wider and longer to reduce the material loads.

[AlexS2.0]

Greame,

The thing about this fiberglass, as some yacht builder told me is that it has a "stable" structure: it works as a sheet, rather than as a number of fibers. It is used for the exterior layers of a fiber-epoxy boat and is supposed to withstand the tension. So, I'll check, if this will do with bows...

[Graeme K]

Hi Alex
I have been around the composite industry for 30 years and I am still not sure what you are referring to.
There are only two types of laminating material that I know of -- one is woven and the other is called chopped strand matt which is made up of lots of fibers cut about ab out 40mm long and lightly bound together.
If you have some other type available I would be very interested to know about it (photo). If it is chopped strand matt that you are referring to then it would be inferior to woven material where at least half of the fibers will run the length of the bow.
The strength requirements for the glass on a bow are unlike most other applications as it only loads the glass in one direction. The outside of a boat hull is stressed in all directions as it is subject to torsional loads

Graeme