Author Topic: Overbuilt?  (Read 4630 times)

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Offline willie

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Re: Overbuilt?
« Reply #30 on: May 26, 2020, 05:43:59 pm »
 
Quote
Pretty much has to be actually, nothing else changes in the COS

could be, but I have a different theory about your COS.

Bows get banished there for being uncooperative. They try to keep a low profile for fear of being tortured again.
When you went snooping around over there, like you did last week, and dragged a few out for another round of interrogation, it made the others straighten right up pretty.

Offline DC

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Re: Overbuilt?
« Reply #31 on: May 26, 2020, 06:09:25 pm »
Does that make me a Bow Nazi?

Offline mmattockx

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Re: Overbuilt?
« Reply #32 on: May 26, 2020, 07:31:42 pm »
willie: it just lost glued in, artificial reflex so that will not happen I think. its still straight and didnt even start taking set.

Can someone explain to me the difference between 'taking set' and 'reflex pulling out'? To my engineer's mind they have to be the same thing. Either the glue line is moving or the wood is moving, it can't be anything else.


With the kiln dried store bought maple that I had I was never sure that I had the grain just so.

Isn't it just straight with no run off? If there is more black magic than just lining the grain up I am doomed.


Did you try putting the branch bow your were having trouble with in a less dry place?

  (lol) (lol)

DC lives on Vancouver Island, there are no less dry places there, it is all wet.


Does that make me a Bow Nazi?

Maybe not a Nazi, but at least a hardass.


Mark

Offline DC

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Re: Overbuilt?
« Reply #33 on: May 26, 2020, 08:15:50 pm »

With the kiln dried store bought maple that I had I was never sure that I had the grain just so.

Isn't it just straight with no run off? If there is more black magic than just lining the grain up I am doomed.



In one dimension I can see the rings. In another it's not so clear cut and I know it's close but, ehhhh!

Offline DC

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Re: Overbuilt?
« Reply #34 on: May 26, 2020, 08:23:00 pm »

Can someone explain to me the difference between 'taking set' and 'reflex pulling out'? To my engineer's mind they have to be the same thing. Either the glue line is moving or the wood is moving, it can't be anything else.



To me "set" is damage to the wood so it's permanently changed from it's natural position.
 When you have artificially, usually with heat, moved the wood from it's natural position to a new position and then, when you bend it, it goes back to it's natural position, that's "pulling out"

Offline Badger

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Re: Overbuilt?
« Reply #35 on: May 26, 2020, 08:52:01 pm »
  The best way I have found to tell the difference is to see if the bow slowly returns to its position after unbracing. A bow that stays the same after unbracing will usually act more like a bow with no set. The more a bow returns the worse it is.

Offline mmattockx

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Re: Overbuilt?
« Reply #36 on: May 27, 2020, 09:07:39 am »
To me "set" is damage to the wood so it's permanently changed from it's natural position.
 When you have artificially, usually with heat, moved the wood from it's natural position to a new position and then, when you bend it, it goes back to it's natural position, that's "pulling out"

I agree set is compression damage to the cells. I see your point on the heat bending, but OP was talking about gluing in reflex and having it pull out. Since the original reflex strain was well below the threshold of damage to the wood (I assume it was well within the elastic limit of the material) and is glued into position instead of being heated, what is there to pull out? Something has to give for it to pull out, probably in the glue line or the wood right next to it.


  The best way I have found to tell the difference is to see if the bow slowly returns to its position after unbracing. A bow that stays the same after unbracing will usually act more like a bow with no set. The more a bow returns the worse it is.

All right, that is a good working definition to go with.


Mark

Offline DC

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Re: Overbuilt?
« Reply #37 on: May 27, 2020, 09:23:02 am »
Quote
I agree set is compression damage to the cells. I see your point on the heat bending, but OP was talking about gluing in reflex and having it pull out. Since the original reflex strain was well below the threshold of damage to the wood (I assume it was well within the elastic limit of the material) and is glued into position instead of being heated, what is there to pull out? Something has to give for it to pull out, probably in the glue line or the wood right next to it.[\quote]

Yeah, that one doesn't work for me either. I'm not sure if I've noticed that. Glue ups are usually pretty solid.

Offline willie

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Re: Overbuilt?
« Reply #38 on: May 27, 2020, 09:59:24 am »
 
Quote
probably in the glue line or the wood right next to it.

An explanation similar to one of the theories behind perry reflex? I have always hoped to understand this better.

Consider the compression on the belly for a moment.

1. If one were to slice off a lam from the belly surface of an untillered bow, one could expect the lam to be just as stiff as any other lam sawn from the stave it came from.

2. if one were to slice off a lam from the belly surface of a bow that has been tillered and shot in, but shows no apparent set. one might expect the lam to be not as stiff as the lam above, but not necessarily deformed.

3. If one were to slice off a lam from the belly surface of a bow that has had the reflex "pulled out", I think one would find a lam that is permanently deformed and would take some effort to straighten. The rest of the bow might return to its glued in reflex profile.

Offline Badger

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Re: Overbuilt?
« Reply #39 on: May 27, 2020, 11:50:53 am »
  Evaluating set is extremely difficult, testing performance when finished is the only true test I think. A stiffer back can pull a rubberized belly back into its profile appearing to have no set when in reality the belly may have turned to jelly.

Offline simk

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Re: Overbuilt?
« Reply #40 on: May 27, 2020, 01:42:36 pm »
after beeing on brace 23h I shot it a while and then tested speed - lost 5fps same arrows - did not count the best shot tough - drawweight @ 26" less 1,5# - set mainly on the outers - looks a little stressed - now curious how it behaves - put it outside over night - left outer is a natural deflex in the belly wood which was glued over an reappeared after bracing, not a good thing but no surprise. 
« Last Edit: May 27, 2020, 01:51:19 pm by simk »
--- the queen rules ----

Offline DC

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Re: Overbuilt?
« Reply #41 on: May 27, 2020, 01:59:09 pm »
3369 were you testing a .270??

Offline Hamish

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Re: Overbuilt?
« Reply #42 on: May 27, 2020, 05:08:47 pm »
Lol, That's one hell of a fast bow.

Offline simk

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Re: Overbuilt?
« Reply #43 on: June 01, 2020, 03:18:31 pm »
and here's the result in pictures: before bracing, after bracing for 24h and then some full drawing...and a little while later. weather this is a good thing or not, this wood is somehow like rubber. its not something my ash backings usually do  8)
--- the queen rules ----

Offline DC

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Re: Overbuilt?
« Reply #44 on: June 01, 2020, 03:59:24 pm »
I've never left a bow braced for 24hrs so I don't know but it looks pretty good to me. How does it look after a couple of hours of shooting?