Horn / core separation
I have had a problem in the first bends of my latest composite (patterned after a Tibetan bow in the Pitt-Rivers Museum, basically an asymmetric Crim-Tatar). I heard a crack whilst bending the upper limb over a tepelik. The horn and core have separated over about a 6 inch section in the mid limb.
This was my first attempt at making a bow with a curved joint between core and horn. I suspect that I was not quick enough at the clamping on the long upper limb.
I can see a number of options:
(1) Warm the limb and try and introduce more glue.
(2) Try and remove the horn strip and reattach.
(3) Completely dismantle and reassemble.
(4) Wrap the limb in sinew and ignore the separation.
I would prefer not to completely dismantle the bow due to the amount of work in reassembling. Introducing some more glue would be the preferred option, but it will be difficult to get the glue into the crack (there is no gap unless the limb is bent). Removal of the horn and re-gluing might be more successful if I clamp the siyahs to a board to stop the sinew pulling the limb into more reflex. I would also need to remove the horn without damaging the sinew backing.
I would be grateful for any suggestions or tips on how to repair.
Andrew
This was my first attempt at making a bow with a curved joint between core and horn. I suspect that I was not quick enough at the clamping on the long upper limb.
I can see a number of options:
(1) Warm the limb and try and introduce more glue.
(2) Try and remove the horn strip and reattach.
(3) Completely dismantle and reassemble.
(4) Wrap the limb in sinew and ignore the separation.
I would prefer not to completely dismantle the bow due to the amount of work in reassembling. Introducing some more glue would be the preferred option, but it will be difficult to get the glue into the crack (there is no gap unless the limb is bent). Removal of the horn and re-gluing might be more successful if I clamp the siyahs to a board to stop the sinew pulling the limb into more reflex. I would also need to remove the horn without damaging the sinew backing.
I would be grateful for any suggestions or tips on how to repair.
Andrew
Andrew, according to my experience the bow is hurted now.
Sometimes a repair has worked fine, but in most cases not.
For to keep the sense of the sinew- backing just heat the "hurted part" of the bow(up to 65Celsius) for to liquefy the old glue and introduce more new glue, clamp it for some days, ground this part of the bow, coat it with a thin solution of glue several times, check the tiller at about 50% of the drawlength, then wrapp it with sinew,soaked in water and glue.
Good luck, Michael
Sometimes a repair has worked fine, but in most cases not.
For to keep the sense of the sinew- backing just heat the "hurted part" of the bow(up to 65Celsius) for to liquefy the old glue and introduce more new glue, clamp it for some days, ground this part of the bow, coat it with a thin solution of glue several times, check the tiller at about 50% of the drawlength, then wrapp it with sinew,soaked in water and glue.
Good luck, Michael
Mi experiences is ... completly dismantle :cry: In composite you can re-use all components. And start again. Trust me , its better , than cosmetic regluening , vith bad end. Now you can see how fast is your glue. Last time i must soaked mi bow 5 days in water and next 6 hours in very hot (about 65 Celsia) .
Dusan, to start a new one is the best you can do, so you?re right. That?s why I posted: the bow is hurted now forever.
But you can?t re-use the sinew- backing, its capablity of withstand tension is gone.
Michael
By the way Dusan, have you ever done any kind of bow by yourself?
But you can?t re-use the sinew- backing, its capablity of withstand tension is gone.
Michael
By the way Dusan, have you ever done any kind of bow by yourself?
:lol: very... silly question, Redhawk :lol: . Yes i have done many bows in this 9 years... But unfortunately for you, i dont want to show mi bows before beeing satisfy vith that.
well sinew you can use in glue cooking.
well sinew you can use in glue cooking.
Just curious why you think you can't re-use a sinew backing. I've done it several times. Perhaps you meant if the bow had to be heated too much to get the sections apart that the sinew may be damaged from the heat.?
Yes. That about it. If you must heated more than 60 celsia, its demaged sinew.
Dusan, you?re right I?m so silly that you make me thinking.
You?re doing a lot of great speeches here, but nobody knows what you?re really capable of and what your real experience is.
As I?ve posted here a sinew- backing is a process called polymerisation.The protein- molecules within the sinew fibres and the glue make chains, these chains build a net of molecular chains becoming more and more closer within some time.
You can break this net by heating it, but the fibres have lost more or less their tension- strength. To reuse these fibres means in any case a loss of energy, a backing made of reused fibres will never be as good as a backing made of fresh fibres.
You can easily do a test, soak a small bundle of sinew- fibres in water, pull it, let it dry, soak it again, pull it..................it feels much more sluggsh now
Michael
You?re doing a lot of great speeches here, but nobody knows what you?re really capable of and what your real experience is.
As I?ve posted here a sinew- backing is a process called polymerisation.The protein- molecules within the sinew fibres and the glue make chains, these chains build a net of molecular chains becoming more and more closer within some time.
You can break this net by heating it, but the fibres have lost more or less their tension- strength. To reuse these fibres means in any case a loss of energy, a backing made of reused fibres will never be as good as a backing made of fresh fibres.
You can easily do a test, soak a small bundle of sinew- fibres in water, pull it, let it dry, soak it again, pull it..................it feels much more sluggsh now
Michael
I understand you, Redhawk.You dont see from me any bow pics. I know that i may look just like a sapient :lol:. But i realy dont like this "not seriouz" hornbows post. I thing, here is nothing to be proud of.
Andrew, the method I wrote about in my book worked for me several times. The injection of glue alone will not do in most cases. The entire cracked section is best immersed in glue and flexed a little to pull it well into the crack, with air bubbles coming in and out. The glue should be thinner, no more than 15% with about 10% alcohol added to reduce the surface tension and very, very hot, The limb does not need to be warmed, since the glue will supply enough heat.
Once done, the excess of glue can be wiped, the limb slightly reflexed to push the parts together and clamped. The clamping is best done after the glue begins to gel. It is sometimes possble the sinew layer could be damaged by clamping. In this case I make padding to conform to the shape of limb beforehand (once I cast the padding from epoxy for example). After a few days the clamps are removed, but the bow should be lef to dry for at least a month.
The section can be wrapped in sinew later depending on the situation.
Good luck
Adam
Once done, the excess of glue can be wiped, the limb slightly reflexed to push the parts together and clamped. The clamping is best done after the glue begins to gel. It is sometimes possble the sinew layer could be damaged by clamping. In this case I make padding to conform to the shape of limb beforehand (once I cast the padding from epoxy for example). After a few days the clamps are removed, but the bow should be lef to dry for at least a month.
The section can be wrapped in sinew later depending on the situation.
Good luck
Adam
Dusan
ATARN is a network where we share some similarities or in other words "archery". Horn bows are part of this and without horn bows many tribes could not conquest other nations or territories (for good or bad). Horn bows are the peak of a development over hundreds of years. Pros and Cons have been discussed in many forums - you can like or dislike them - you can compare horn bows with selfbows or whatever you want. We are open minded.
Redhawk was asking you a simple question to show us some pictures of your bows. Your sometimes destructive comments also in some ATARN posts before show us, that we cannot take you serious - and this has nothing to do with your English or know how.
Just make ONE hornbow and show us your result in ATARN. You can be sure you will get a positive feedback or support not matter whether it is a good or bad bow, whether it works or not. I am sure, real ATARNOs will not make any stupid comments and devalue the result. All of us who ever made a horn bow, know it takes a lot of time to build one and sometimes "the doing/making of... and not the result counts more".
We look forward to seeing your bow,s.
Reto
ATARN is a network where we share some similarities or in other words "archery". Horn bows are part of this and without horn bows many tribes could not conquest other nations or territories (for good or bad). Horn bows are the peak of a development over hundreds of years. Pros and Cons have been discussed in many forums - you can like or dislike them - you can compare horn bows with selfbows or whatever you want. We are open minded.
Redhawk was asking you a simple question to show us some pictures of your bows. Your sometimes destructive comments also in some ATARN posts before show us, that we cannot take you serious - and this has nothing to do with your English or know how.
Just make ONE hornbow and show us your result in ATARN. You can be sure you will get a positive feedback or support not matter whether it is a good or bad bow, whether it works or not. I am sure, real ATARNOs will not make any stupid comments and devalue the result. All of us who ever made a horn bow, know it takes a lot of time to build one and sometimes "the doing/making of... and not the result counts more".
We look forward to seeing your bow,s.
Reto
Thanks for the advice everyone.
I will try with Adam's technique of soaking the limb in hot glare and flexing (which I managed to miss in his book). The main difficulty is working out what sort of container to use for the glue that is long enough to get the limb into (20+" to allow for flexing).
Regards
Andrew
I will try with Adam's technique of soaking the limb in hot glare and flexing (which I managed to miss in his book). The main difficulty is working out what sort of container to use for the glue that is long enough to get the limb into (20+" to allow for flexing).
Regards
Andrew
Reto,
you dont understand me. I dont be afraid of atarn (or other ) members opinion about mi bow :lol:. Its no problem show ONE or MORE of mi bows and describe how good and super speed he shooting ... I work in same sistem like in mi artwork. I dont show mi work before i am satisfide vith . I work ONLY for miself and i competition only vith mi idea how bow must work.Its not about Atarn member opinion or sombody else. I must be first satisfi. Next i can show mi work. If not , all mi criticism and "destructive comments" was nonsense pose. I can promise you, that about year ( when all 8 new generation bows dry - i hope you understand me , you vait vith your bows to...) i show mi last work.
I working in composite bows about 9-8 years . But this is not permanent work . All this time i have new and new information and bows was better and better , BUT not like i dream. Last 3 years i have very interesting and hard work vith no time working on mi hobby. I call this time " collection time"( material and information ) .Bows who was "shootable" from this years endid like gift mi friends or some i sell, most was recykled (because horn ) .Mi last generation is now in work . 4 bows was sineved and dry. 4 another was shaped before sinewing. I show only succesfull working bows from this 8 about 1-1,5 year . Thats mi curriculum vitae. Thats enough, boys.
you dont understand me. I dont be afraid of atarn (or other ) members opinion about mi bow :lol:. Its no problem show ONE or MORE of mi bows and describe how good and super speed he shooting ... I work in same sistem like in mi artwork. I dont show mi work before i am satisfide vith . I work ONLY for miself and i competition only vith mi idea how bow must work.Its not about Atarn member opinion or sombody else. I must be first satisfi. Next i can show mi work. If not , all mi criticism and "destructive comments" was nonsense pose. I can promise you, that about year ( when all 8 new generation bows dry - i hope you understand me , you vait vith your bows to...) i show mi last work.
I working in composite bows about 9-8 years . But this is not permanent work . All this time i have new and new information and bows was better and better , BUT not like i dream. Last 3 years i have very interesting and hard work vith no time working on mi hobby. I call this time " collection time"( material and information ) .Bows who was "shootable" from this years endid like gift mi friends or some i sell, most was recykled (because horn ) .Mi last generation is now in work . 4 bows was sineved and dry. 4 another was shaped before sinewing. I show only succesfull working bows from this 8 about 1-1,5 year . Thats mi curriculum vitae. Thats enough, boys.
Andrew and all; I am somewhat slow and also experience glue drying during assembly. This also happens to Korean buwyers. They add water with a brush during assembly and reheat as necessary. The heat reactivates the moisture held in the glue and re softens it.
For this reason I assemble with inner tube strips from a car inner tube. That way when the bow is reheated, the flue oozes out from the spaces between the tube strips. The whole is attached to a form to keep things lined up. Jack
For this reason I assemble with inner tube strips from a car inner tube. That way when the bow is reheated, the flue oozes out from the spaces between the tube strips. The whole is attached to a form to keep things lined up. Jack
Well I have done bows from old parts. I cant tell if they are worse then bows made of new parts. But they shot and have sometimes efficiency close to the best bows on net and speed also.
Reused sinew works fine for me.
Horn strip removed with heat gun can be replaced with new. Horn strip removed with heat gun can be put on an other bow and still be as new.
So in this case I would just take the heat gun and remove the strip and glue it again.
Reused sinew works fine for me.
Horn strip removed with heat gun can be replaced with new. Horn strip removed with heat gun can be put on an other bow and still be as new.
So in this case I would just take the heat gun and remove the strip and glue it again.
So far, nobody proposed Epoxy. I have no experience in using this kind of glue for my bows, but, under certain circumstances, would it make sense to use Epoxy to fill in and close the gap/separation between core and horn? What is the risk and how about the performance? I can imagine that from the processing point of view it might be easier and we simply close both eyes of not being that traditional.
Reto
Reto
Reto
Modern and traditional glues do not stick well to each other. The epoxies I have used in the past are much thicker than hide glue so would be even more difficult to get into the gap.
I used epoxy for horn/core on my early composites. It is easier to attach the horn as you can take your time, but I am not sure it is flexible enough as I have had several horn/core separation problems and repair is almost impossible as the glue won't melt with heat.
As I mentioned before, I will try soaking the limb in hot glue. If my initial gluing was too bad for this to work I will try removing the horn with heat and regluing. I would prefer not to do this as there is a risk of damaging the sinew backing with the heat and the limb will need immobilising to avoid the sinew backing pulling the core into a silly reflex without the horn.
Regards
Andrew
Modern and traditional glues do not stick well to each other. The epoxies I have used in the past are much thicker than hide glue so would be even more difficult to get into the gap.
I used epoxy for horn/core on my early composites. It is easier to attach the horn as you can take your time, but I am not sure it is flexible enough as I have had several horn/core separation problems and repair is almost impossible as the glue won't melt with heat.
As I mentioned before, I will try soaking the limb in hot glue. If my initial gluing was too bad for this to work I will try removing the horn with heat and regluing. I would prefer not to do this as there is a risk of damaging the sinew backing with the heat and the limb will need immobilising to avoid the sinew backing pulling the core into a silly reflex without the horn.
Regards
Andrew
One type of epoxy that may hold promise for composite bows is the new G-Flex epoxy by WEST systems. It is extremely flexible and resistant to shock, expansion and contraction and vibration. Sounds perfect for a highly stressed bow.
Who first talk about epoxy ? :lol:
I have soaked the limb in hot glue and flexed it until the bubbles stopped. This took longer than I expected.
I will find out if it worked in a month or so.
Andrew
I will find out if it worked in a month or so.
Andrew