Please help with horn inspection
I work on the horn plates, which i got last week, and have several problems which i would like to discuss here and please to listen opinion of experienced bowyers.
One of the stripe had the several deep cracks 30 cm from the base, so the final plate is only 42 cm long (Is it useful for the bow with 100 cm long wood core, which i plan, (horn plate on the tip side is only 2,5 cm width?)
The second problem is, that because of deep ?gaps? on the surface of the horn, the plate is now only 3-4 mm thick (is it OK for the 45-50 lbs bow, what i wont to get? What about groovings, they wil lead to another attenuation of the plate?)
Third problem are places of different - yellow/brown colour as you can see on the attached picture.When i scraped this area, the feeling was little bit different then other places - like more frangible.
My last question deals with glueing the horn to the core. I registered illuminative discussion here on ATARN, in the past, and Stephen cited there some chinese instruction about many times repeated coating of very diluted glue to the surface of both parts (horn and core). Is the purpose of this only in better glueing, or it leads to improving of mechanical qualities of the core and wood itself? I mean, that self bow, saturated by many layers of the fine issinglas will be better than another one without this cure?
Thanks a lot for any help!
One of the stripe had the several deep cracks 30 cm from the base, so the final plate is only 42 cm long (Is it useful for the bow with 100 cm long wood core, which i plan, (horn plate on the tip side is only 2,5 cm width?)
The second problem is, that because of deep ?gaps? on the surface of the horn, the plate is now only 3-4 mm thick (is it OK for the 45-50 lbs bow, what i wont to get? What about groovings, they wil lead to another attenuation of the plate?)
Third problem are places of different - yellow/brown colour as you can see on the attached picture.When i scraped this area, the feeling was little bit different then other places - like more frangible.
My last question deals with glueing the horn to the core. I registered illuminative discussion here on ATARN, in the past, and Stephen cited there some chinese instruction about many times repeated coating of very diluted glue to the surface of both parts (horn and core). Is the purpose of this only in better glueing, or it leads to improving of mechanical qualities of the core and wood itself? I mean, that self bow, saturated by many layers of the fine issinglas will be better than another one without this cure?
Thanks a lot for any help!
Can't help you on your horn questions. Although I would like to ask, how flexible are your strips? Are these things fairly stiff or very pliable? I ask because I'm prepping some horn strips myself and mine are not stiff. I assume the stiffness will be enhanced when they are glued to the core, much as bamboo is flexible by itself yet extremely stiff when used as a backing.
As for the glue question, I would imagine that the thin glue will certainly allow better and more complete penetration into the crevices/grooves of the wood surface, even to the point of infusing somewhat down into the wood (although deep penetration is probably not happening). A thin glue for the first coats, would definitely get into the roughened surface better than a thick coat. The grooves are put in the surfaces in the first place to increase surface area, so it is imperative that they all contain glue or there is no benefit, in fact if there are air pockets in the grooves this would be potentially be a weaker situation than simply glueing the surfaces without grooves.
This is coming from someone with no experience in Asiatic composites, but some experience in backed bows and sinewed bows. So take it for what it is worth.
As for the glue question, I would imagine that the thin glue will certainly allow better and more complete penetration into the crevices/grooves of the wood surface, even to the point of infusing somewhat down into the wood (although deep penetration is probably not happening). A thin glue for the first coats, would definitely get into the roughened surface better than a thick coat. The grooves are put in the surfaces in the first place to increase surface area, so it is imperative that they all contain glue or there is no benefit, in fact if there are air pockets in the grooves this would be potentially be a weaker situation than simply glueing the surfaces without grooves.
This is coming from someone with no experience in Asiatic composites, but some experience in backed bows and sinewed bows. So take it for what it is worth.
Michal
You have a number of options if the strip is not long enough. If the other strip is longer, the joint does not have to be in the middle of the grip (as long as it is not in the bending limb). You can also add an extra strip in the grip to get some more length. Another alternative is to make the bow slightly shorter. I only had access to fairly short strips for my first couple of bows, so made up the length with odd pieces of horn in the grip and even under the siyah bases.
The 3-4mm thickness is not a problem. My last MB style bow used circa 3.2mm thick horn, tapering fractionally down the length. The horn can be thicker in the grip, but it is not essential.
Is yellow/brown patch visible on the under side of the strip? If not, it may not be a problem at the edge of the strip, as it may disappear as the strip is rounded. Is it at the grip or siyah-base end of the strip? If at the siyah end, you may loose most of it with the width tapering.
Regards
Andrew
You have a number of options if the strip is not long enough. If the other strip is longer, the joint does not have to be in the middle of the grip (as long as it is not in the bending limb). You can also add an extra strip in the grip to get some more length. Another alternative is to make the bow slightly shorter. I only had access to fairly short strips for my first couple of bows, so made up the length with odd pieces of horn in the grip and even under the siyah bases.
The 3-4mm thickness is not a problem. My last MB style bow used circa 3.2mm thick horn, tapering fractionally down the length. The horn can be thicker in the grip, but it is not essential.
Is yellow/brown patch visible on the under side of the strip? If not, it may not be a problem at the edge of the strip, as it may disappear as the strip is rounded. Is it at the grip or siyah-base end of the strip? If at the siyah end, you may loose most of it with the width tapering.
Regards
Andrew
Andrew: thanks for your advice. On the base side of horn plate (on the image), the decoloration is only on the upper side. But another area is on the tip side (see the picture). And go through the horn plate. I hope, that when theese potentially problematic areas are not in the middle - bending part, it wont touch mechanics of the limb. After your advice, i will work with separate plates under the siyahs base and the grip.
Would you make groovings on such a thin plate?
Lennie:as i can say (my plates are the first i keep in my hands) they are stiff, even in their low thickness (3-4 mm). Its an adventure with first composite, isnt it? (Well quite expensive)
Would you make groovings on such a thin plate?
Lennie:as i can say (my plates are the first i keep in my hands) they are stiff, even in their low thickness (3-4 mm). Its an adventure with first composite, isnt it? (Well quite expensive)