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Crimean tartar style horn bow build along
superdav95:
Yes. I did heat up the horn with a radiant space heater prior to glue and sizing. The core of bow the same. My core was pretty thin if you remember and so when the horn was put on it was slightly thicker then the core actually in some place until I did some scraping and filing. This bow will be a 50lbs draw weight bow or under when done I suspect. After a few more days of drying it’s a little better shape now. Gonna do a second layer this week on it and see where we end up when it dries. Again thanks for the input.
Dave
superdav95:
Second layer done! That’s a total of 63grams so far. Last layer will be in couple weeks. That final layer will be about 20grams bringing my total to around just over 80grams. Attached is a pic from Adams book of how I’m layering out the sinew fyi. Hope it works out. Thanks for looking and for the feedback
Cheers
superdav95:
Well there bad news and good news. The sinew on this bow failed. Or more appropriate I failed to lay the sinew properly on this particular bow. I used 10% glue solution when sizing the freshly grooved back of the wood core but I think I must have starved the glue and was little too light on the glue and had starved the core and sinew of glue. You can see where it lifted in the middle of each limb. The good news is that I may still be able to salvage the core and horn as it remained intact. I was able to pull off the sinew in one layer with some effort and even save the sinew. The silver lining too is that the sinew came off in one piece and Undamaged as far as I can tell. My initial thinking was to put first two layers on as just top layers and not overlap around the core onto a little bit of the edge of the horn. I was then gonna use the third layer to wrap around core onto the horn for final layer then cover with thin rawhide. I never got that far unfortunately or fortunately depending how I look at it cause a failure at this stave is better then having it fail after drying time after third layer I guess. Glass half full. I wonder if I should have wrapped the first two layers also or if this would have made a difference in the end. It may be a number of things that caused the sinew to pull away. When pulling off the remaining sinew I noticed that parts of the limbs seemed dry and as if no glue at all. Other parts the wood pulled off with the sinew. I remember heating up the core wood prior to sizing with glue. I wonder if I did not have enough layers of glue or that I didn’t use a strong enough concentration of glue when sizing. I weighted the glue to about 10%. Then used 20-30% for sinew laying. I used straight sturgeon glue not mixed with hide glue. In Adams book he mentions the mixing amounts of hide and bladder glue for the sinew. I would love to hear what you guys think about this and where I may have gone wrong. Thanks in advance.
Going to try and salvage my core and try again.
Cheers
bownarra:
Morethan likely the sizing wasn't sufficent on the core.
the safest way to size is to use very thin glue, like 5%. Even if it is only for the first few coats. The thin glue really 'gets into' the core. Same when gluing horn. The importance of sizing can be overlooked.
My hornbow failures in the beginning were mainly sinew lifting off the core. After the 3rd bow doing this I contacted Adam Karpowzi and asked his advise. Very thin glue for the sizing and 30% for the first layer of sinew. I followed his advise and haven't had a failure since. Often these things are only subtle....but these bows present a steep learning curve!
Could you show a picture of the core where sinew lifted.
superdav95:
--- Quote from: bownarra on March 31, 2022, 04:24:19 am ---Morethan likely the sizing wasn't sufficent on the core.
the safest way to size is to use very thin glue, like 5%. Even if it is only for the first few coats. The thin glue really 'gets into' the core. Same when gluing horn. The importance of sizing can be overlooked.
My hornbow failures in the beginning were mainly sinew lifting off the core. After the 3rd bow doing this I contacted Adam Karpowzi and asked his advise. Very thin glue for the sizing and 30% for the first layer of sinew. I followed his advise and haven't had a failure since. Often these things are only subtle....but these bows present a steep learning curve!
Could you show a picture of the core where sinew lifted.
--- End quote ---
Ok. That makes sense actually. Thanks for your input. In the pics it looks pretty dry looking to me I made sure the grooves were good and clean and warmed up the core before sizing a number of times. 3-4 times. I’ll try and use the method you suggest when I reapply the sinew. I reread Adams portion of the book and he mentions too that it should wrap around the core and around onto the horn and bit too. I didn’t do that with first two layers and wonder if that was part of problem too. Here’s a few pics of core after pulling sinew off. In the mean time I was able to salvage the sinew cleaned it all and separated it all and weighed it all again.
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