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Sneak peak.
superdav95:
With the back trapped I would lean more to tension was little compromised over the compression. Just my way of looking at it. If the back is trapped would that not be putting more strain on the back to beef up your belly a bit if one was worried about compression failing a little this could be a balance that is struck. In this case it would seem to me that unless I could see some evidence of crystallization happening on the belly I would be looking more at the back as the culprit perhaps. Could still be a bit of both tension and compression and bow has just settle in now to where it will be but if no obvious signs of compression happening I would lean to tension being the cause. Just my thoughts on it. Wet nice bow still regardless. Congrats!
mmattockx:
--- Quote from: Selfbowman on January 01, 2023, 11:32:24 am ---So I’ve always heard that Osage was pretty even in compression and tension. This trapping makes me wonder how true that is. Less mass on the back but it is still failing to compression??? Explain to me in the most simple terms possible please.
--- End quote ---
Without having precise measurements of your trapping I can only guess, but it is hard to shift the neutral axis much more than 10-12% with trapping unless you really go nuts with it and it doesn't look like you did from the pictures. A 10% neutral axis shift adds 10% to the tension stresses and reduces the compression stresses by 10%. Very few woods are close to even on the tension limit versus the compression limit, so even if your osage compression limit was only 15% less than the tension limit it still would have failed in compression first.
Many (probably most) hardwoods have the compression limit at 50-60% of tension, so your osage would be considered really good at 85% but still not good enough to avoid taking set.
Mark
Bob Barnes:
--- Quote from: mmattockx on January 01, 2023, 01:54:44 pm ---
--- Quote from: Selfbowman on January 01, 2023, 11:32:24 am ---So I’ve always heard that Osage was pretty even in compression and tension. This trapping makes me wonder how true that is. Less mass on the back but it is still failing to compression??? Explain to me in the most simple terms possible please.
--- End quote ---
Without having precise measurements of your trapping I can only guess, but it is hard to shift the neutral axis much more than 10-12% with trapping unless you really go nuts with it and it doesn't look like you did from the pictures. A 10% neutral axis shift adds 10% to the tension stresses and reduces the compression stresses by 10%. Very few woods are close to even on the tension limit versus the compression limit, so even if your osage compression limit was only 15% less than the tension limit it still would have failed in compression first.
Many (probably most) hardwoods have the compression limit at 50-60% of tension, so your osage would be considered really good at 85% but still not good enough to avoid taking set.
Mark
--- End quote ---
"New bow design somewhat.67” ntn,9” handle, 1-1/8 at fades, 9/32 at tip, pyramid. Trapped on the back3/8 total. Pretty much the whole limb.3/16” on each side."
Selfbowman:
Ok Mark I’ll try one trapped to the limits . Give me the the dimensions for a narrow pyramid bow similar to this one. From what I understand what you said the mass may get down to5-6 oz per limb on this bow.
Selfbowman:
Mark I feel it’s failing in tension and here is why. I think the neutral Plane has changed with the trapping because of less mass . If we was to bend that limb the opposite way it would fail miserably I think we could all agree. The problem may be by reducing the elastic abilities or properties in the mass it’s stretch did not return to its original state. If I shoot this bow a thousand times it might fail eventually. We just can’t see the damage. I still think that perfect diminishing mass is where we will find the best performance. By adding reflex on the ends we have a need for more mass at inner limbs. It’s been a interesting build though. If thicker is quicker can we ever reduce the mass in the limbs of a 67” bow with a 8-10” handle to closer to 6oz instead of 8 oz??
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