Building angular composite bow
Hello to everybody.
I am new to this forum, and new to building horn bows in general, so I will appreciate any help from others.
I am planning to build composite bow based on bows found in tomb of tutankhamen. I have found source for all materials needed, but before buying I want to make sure I know how to build one of these bows, so I will ask several questions that bother me.
First of all, my bow will be around 135 cm long along the curves, so I want to know how long water buffalo horn backstrips will I need to achieve given length(I will splice 2 horns in the handle)? Also, how thick layer of horn can I get from one horn backstrip?
Secondly, if my bow will taper from 2cm thickness at middle to about 1cm near the tips, should I taper horn, sinew and core uniformly(so that at every part of limb's cross section ratio of materials is the same) or?
Another thing, how could I predict draw weight?
There are probably more questions I cant think of at the moment, but also if anyone has any tips on building composite bows in general, or this particular type of bow, you are welcome to post it.
I am new to this forum, and new to building horn bows in general, so I will appreciate any help from others.
I am planning to build composite bow based on bows found in tomb of tutankhamen. I have found source for all materials needed, but before buying I want to make sure I know how to build one of these bows, so I will ask several questions that bother me.
First of all, my bow will be around 135 cm long along the curves, so I want to know how long water buffalo horn backstrips will I need to achieve given length(I will splice 2 horns in the handle)? Also, how thick layer of horn can I get from one horn backstrip?
Secondly, if my bow will taper from 2cm thickness at middle to about 1cm near the tips, should I taper horn, sinew and core uniformly(so that at every part of limb's cross section ratio of materials is the same) or?
Another thing, how could I predict draw weight?
There are probably more questions I cant think of at the moment, but also if anyone has any tips on building composite bows in general, or this particular type of bow, you are welcome to post it.
I'm not really familiar with the design of the Egyptian bows but as a rule of thumb always buy the longest horns you can get!
Yes the two horns will be butted up against each other in the hnadle section. You can also use a 'spacer' made of another hard material to get you a bit more length. It can be upto about 2 inches long. Horn,antler,bone,dense hardwood will all work fine.
the thickness will really depend on the individual horns. I have had horns that have given me 8mm thick strips but they are rare in my experience, an average is more like 4 - 5mm in the bendings sections. The strip will end up with a natural taper anyway.
I would advise keeping your sinew the same thickness for most of the limb length for safety. The horn will be tapered anyway so the rest of the taper should be in your core before sinew application.
Your last question is the tricky part! Maybe someone with experience of making one of these bows will answer that for you. If not then you will need to make a 'prototype' to give you an idea of thickness versus draw weight. Or copy one of the finds dimensions if they are available?
Yes the two horns will be butted up against each other in the hnadle section. You can also use a 'spacer' made of another hard material to get you a bit more length. It can be upto about 2 inches long. Horn,antler,bone,dense hardwood will all work fine.
the thickness will really depend on the individual horns. I have had horns that have given me 8mm thick strips but they are rare in my experience, an average is more like 4 - 5mm in the bendings sections. The strip will end up with a natural taper anyway.
I would advise keeping your sinew the same thickness for most of the limb length for safety. The horn will be tapered anyway so the rest of the taper should be in your core before sinew application.
Your last question is the tricky part! Maybe someone with experience of making one of these bows will answer that for you. If not then you will need to make a 'prototype' to give you an idea of thickness versus draw weight. Or copy one of the finds dimensions if they are available?
Well I would like to buy longest horns I can, but unfortunately I am on a budget, and for price of two 80cm horns I can get three 70cm horns, so it would be helpful to know what percentage of a complete backstrip is usable for a bow.
I would rather not use a spacer(unless it is neccessary for some reason) since complete length of this kind of bow is 'working', if you understand what I mean. Should I do a V splice or something at the middle, or not?
About draw weight, my plan is to get it around 50kg at 85cm, which is my natural draw length. By copying one of dimensions I am afraid I will end up with too light or too heavy bow.
Also, I have noticed that most finds are a little asymmetric, one limb is around 2cm longer, but I dont know was that accidental or planned. If anyone could help me explain if and why should I(or shouldn not) make my bow asymmetric it would be helpful.
I would rather not use a spacer(unless it is neccessary for some reason) since complete length of this kind of bow is 'working', if you understand what I mean. Should I do a V splice or something at the middle, or not?
About draw weight, my plan is to get it around 50kg at 85cm, which is my natural draw length. By copying one of dimensions I am afraid I will end up with too light or too heavy bow.
Also, I have noticed that most finds are a little asymmetric, one limb is around 2cm longer, but I dont know was that accidental or planned. If anyone could help me explain if and why should I(or shouldn not) make my bow asymmetric it would be helpful.
The reason for an asymmetrical designs is that a bows lower limb needs to be stronger for the bow to be balanced at full draw. It would certainly have been designed that way.
You should copy an existing design and see what weight it comes out at then adjust from there. it is the only way to do it other than deliberately making it too heavy then thinning the horn. However the thickness of your horn will determmine how far you can go with that. Making a hornbow is similar ito making glass bows is that respect eg. you need to make at least one working 'protoype' to get a stack verus draw weight ratio.
A spacer with a butt joint is the normal way top make horn bows. A v splice will fail.
Making hornbows is never going to be cheap and without somebody who really knows what they are doing then a lot of experimentation is really the only way to go. You are setting yourself up for failure if you expect your first hornbow to be perfect. It is impossible for any of us to accurately say that yes x length of horn will give you y length and z thickness. You are dealing with natural materials and there are no guarantees. Trust me buy the longest horns you can for this design of bow!
You should copy an existing design and see what weight it comes out at then adjust from there. it is the only way to do it other than deliberately making it too heavy then thinning the horn. However the thickness of your horn will determmine how far you can go with that. Making a hornbow is similar ito making glass bows is that respect eg. you need to make at least one working 'protoype' to get a stack verus draw weight ratio.
A spacer with a butt joint is the normal way top make horn bows. A v splice will fail.
Making hornbows is never going to be cheap and without somebody who really knows what they are doing then a lot of experimentation is really the only way to go. You are setting yourself up for failure if you expect your first hornbow to be perfect. It is impossible for any of us to accurately say that yes x length of horn will give you y length and z thickness. You are dealing with natural materials and there are no guarantees. Trust me buy the longest horns you can for this design of bow!
Thank you for your answers first of all, I find them really helpful.
I would like to ask several more questions.
I was thinking, since horn on my bow will be cca 25mm wide at widest point, and as I heard buffalo horn strips are 50+mm wide, how about spliting one horn strip in half lengthwise?
Regarding draw weight, say I end up with too light bow, is it possible to glue another thin strip of horn on the belly and add some sinew on back to balance it? Some original bows have indeed had 2 horn strips glued together on belly, and even one thin strip on the back of the core, beneath the sinew.
Also, about sinew, how much of it do I need? Say my bow will be 135cm long, average width 2cm, and sinew will probably be 5mm thick. How many(grams, pieces, whatever) will I need? Of course, I am not asking for accurate estimation, I just wanna know roughly how much to buy?
I would like to ask several more questions.
I was thinking, since horn on my bow will be cca 25mm wide at widest point, and as I heard buffalo horn strips are 50+mm wide, how about spliting one horn strip in half lengthwise?
Regarding draw weight, say I end up with too light bow, is it possible to glue another thin strip of horn on the belly and add some sinew on back to balance it? Some original bows have indeed had 2 horn strips glued together on belly, and even one thin strip on the back of the core, beneath the sinew.
Also, about sinew, how much of it do I need? Say my bow will be 135cm long, average width 2cm, and sinew will probably be 5mm thick. How many(grams, pieces, whatever) will I need? Of course, I am not asking for accurate estimation, I just wanna know roughly how much to buy?