2 horn bow
Hello,
This is my 2 bow. It pulls 42 lbs at 28 inch.It's lenght is 115 cm outer curve unstung. Strung the lenght is 106 cm between the nocks.
I started with making the horn plates 48 cm 9mm thick tapering toward the nock to 3mm. The core is a lath of oak 3mm in thickness. The lath was a horisontal one with NO reflex. The wooden tips are ash with a horn piece glued into it.
Grooved the horn and wood used hideglue and ostrich sinew.
Before laying the 1 layer of sinew I pulled the bow into a reflex holding it with a piece of rope.
There are 4 layers of ostrich sinew and the bow has cured for 5 weeks
afther the last layer of sinew. Between the sinewing I pulled to bow into more reflex.
Is 42 lbs not a little bit to weak for 4 sinew layers???
I was hoping for 60 lbs.
What did I do wrong making this bow.
Please coment.
This is my 2 bow. It pulls 42 lbs at 28 inch.It's lenght is 115 cm outer curve unstung. Strung the lenght is 106 cm between the nocks.
I started with making the horn plates 48 cm 9mm thick tapering toward the nock to 3mm. The core is a lath of oak 3mm in thickness. The lath was a horisontal one with NO reflex. The wooden tips are ash with a horn piece glued into it.
Grooved the horn and wood used hideglue and ostrich sinew.
Before laying the 1 layer of sinew I pulled the bow into a reflex holding it with a piece of rope.
There are 4 layers of ostrich sinew and the bow has cured for 5 weeks
afther the last layer of sinew. Between the sinewing I pulled to bow into more reflex.
Is 42 lbs not a little bit to weak for 4 sinew layers???
I was hoping for 60 lbs.
What did I do wrong making this bow.
Please coment.
Nice bow!
Regarding your question, I also made my second bow recently, so I'm not very experienced, but maybe some data from my bow might be helpful. It's slightly longer than yours, and more reflexed, both at handle and siyahs, 122cm ntn along the belly. Core is maple, a little less than 4mm, horn about the same, with very little taper. Three sinew layers. (deer, have never tried ostrich) Total thickness at midlimb 10.5mm. It draws 53 pounds @ 28". I to had hoped for about 10 more pounds. :)
Things you might look into as reasons for draweight: Your core is not very thick. What is the thickness of horn, and total thickness at an average along the bending section. I don't think draweight depends only on number of sinew layers. Another thing, you say your bow cured for 5 weeks. I think it's reccomended to cure hornbows for min 6 months. Can it be somthing there? (mine cured for 5 months, I too ran out of patience)
Regarding your question, I also made my second bow recently, so I'm not very experienced, but maybe some data from my bow might be helpful. It's slightly longer than yours, and more reflexed, both at handle and siyahs, 122cm ntn along the belly. Core is maple, a little less than 4mm, horn about the same, with very little taper. Three sinew layers. (deer, have never tried ostrich) Total thickness at midlimb 10.5mm. It draws 53 pounds @ 28". I to had hoped for about 10 more pounds. :)
Things you might look into as reasons for draweight: Your core is not very thick. What is the thickness of horn, and total thickness at an average along the bending section. I don't think draweight depends only on number of sinew layers. Another thing, you say your bow cured for 5 weeks. I think it's reccomended to cure hornbows for min 6 months. Can it be somthing there? (mine cured for 5 months, I too ran out of patience)
Yuna, There is nothing wrong with your bow. It passed the first test- the stringing. Now shoot it for a while, get to know it and learn from it. Maybe your next one will be better. You have built a hornbow.
There is nothing wrong, it did stay together.
If there is too low draw weight, it means that you should have had thicker core and/or thicker horn.
twice as tick bow is 8 timer more draw weight, so
(60#/42#)^(1/3)=1.13
So 13% thicker core+horn would have made 60# (...or broken bow, or side bending problem or)
If there is too low draw weight, it means that you should have had thicker core and/or thicker horn.
twice as tick bow is 8 timer more draw weight, so
(60#/42#)^(1/3)=1.13
So 13% thicker core+horn would have made 60# (...or broken bow, or side bending problem or)
nice bow !
same opinion :lol:
same opinion :lol:
Congrats!
I think most of us who have made horn bows find that it is very difficult to hit a specific draw weight with the first or second bow of a certain type. But that's also the cool thing about horn bows. There seems to be an near endless learning curve to climb. Slow and labour intensive, compared to wooden bows, but shooting a self made horn bow makes it all worth it!
Anyway, I thought I'd bring some constructive criticism: Do the sinew wrapping after you have put on all the longitudinal sinew layers that you want.
I think most of us who have made horn bows find that it is very difficult to hit a specific draw weight with the first or second bow of a certain type. But that's also the cool thing about horn bows. There seems to be an near endless learning curve to climb. Slow and labour intensive, compared to wooden bows, but shooting a self made horn bow makes it all worth it!
Anyway, I thought I'd bring some constructive criticism: Do the sinew wrapping after you have put on all the longitudinal sinew layers that you want.
thank's for the positive coments.It has been very helpfull.
What I don't understand is why sinew must cure for so long. If the glue is cured and the sinew schrank why does a horn bow has to cure for that time???
What happens inside the bow and/or the sinew????
grtz,
Erwin
What I don't understand is why sinew must cure for so long. If the glue is cured and the sinew schrank why does a horn bow has to cure for that time???
What happens inside the bow and/or the sinew????
grtz,
Erwin
all many classical sources mention curing times of several months (at least 6 months). one can also roughly caluculate that it takes 6 months for the sinew layer to dry (see Adam Karpowicz' book). In principle the glue molecules bind together by non-covalent chemical bonds which get stronger with dehydration.
does that mean that the bow will get stronger afther curing for 6 month's?
The bow is now not in a reflex position and is has been shot. Should I just leave it resting now or do I have to put it in reflex again to cure??
The bow is now not in a reflex position and is has been shot. Should I just leave it resting now or do I have to put it in reflex again to cure??
Add more sinew onto the back will increase poundage.