Different kinds of set

[tom sawyer]

Steve I think I did address the "kind of set" issue.  An overbuilt bow will have a different kind of set because its wood isn't compressed to the point where it is uniform.  I think it would be the "spongier" kind of set you are talking about.  A bow that has experienced near-maximal compression, would be hardened to its max and probably wouldn't be spongy or return sa quickly or as fast.  Or is this still not pertaining to your discussion?

[Badger]

Lennie, yest thats what I was talking about. I think the overworked underbuilt bow gets spongier than the overbuilt bow in most cases. However, I have experienced what you are talking about with hickory. Very often I am not able to get hickory to conform to my own mass theory. Most of the time it is because of moisture levels which for most woods would be acceptable. In these cases the bow is wider than should be needed but as you are saying on the spongy side, nothing extreme but not that good hard crisp feeling we have all come to know and love. Steve

[Dan Perry]

Steve,

Hickory is tricky.  It likes to be drier than other woods.  I had a longbow that I left in the house with the swamp cooler running all summer, then entered it in competition.  This bow had already set several records.  I had narrowed it and entered it in the 35# class.
It was a dead stick.  I have it in my hot and dry shop now.  I want to shoot it again at the end of the summer and see what it does.

It was Perry Reflexed, so it didn't show the set you would see normally, but it went spongy.  Also, with hickory, I don't but it unless it is dense, resonous wood.  The growth rings are mere dotted lines.

The 50# self bow broad head record you broke was set by Dewayne Smith with a Maple long bow I built, 72" long with 2 to 2 1/2 inches of set.  It shot the broad head 202 yards. (He out shot me with my own bow!  LOL It happens all the time)

What Lennie says about the compression taking most of the set is true.  My point is Not that huge amounts of set are taking place in tension, but that there may be some set taking place here that we haven't looked for.  You start to suspect the elasticity of woods when you build a lot of backed bows.  You use the E- mod. of woods to compliment each other, but elastic modules is how hard a wood is to stretch.  It has nothing to do with how elastic it is.  I believe that some woods may stretch past the point of being able to return, and still be elastic enough to hold together.

As far as spring growth goes, I don't like woods that have a huge difference between the strength of the spring growth and hard growth.  I hate it when a bow drops 15# of draw weight when broken in.  It can be quite a guessing game.

Steve you wanted to identify different kinds of set.  Here are 4 different kinds of set.  Tension, moisture, Early growth break down
between growth rings, and compression set.  It seems that your real question is, Does the set "always" compromise the fibers, and their ability to return to their shape when strained.  You have already answered that question.  This all comes back to what we talked about on another thread.  We walk all around the real issue of how bows really work and why the mass theory model works as well as it does, without standing directly on the issue.  I am working on this for my book, but their is some key info that I need before it is ready.

Dan

[Justin Snyder]

Steve, I think you could adjust your mass theory for hickory.  Weigh a piece at 9% MC like any other bow would like.  Dry it out to 6% and weigh it again.  Now subtract the difference from the weight in your mass formula.  After you have an idea what the weight will be, you could just subtract it from all hickory bows.
Lets say you have a bow you want to end up at 21oz.  You weigh it at 9% and it is 25oz.  You weigh it again at 6% and it is 21oz.  You just subtract that 4oz from the final.  21oz-4oz=17oz   You want to tiller the drier bow to weigh 17oz.  Justin

[Dan Perry]

Justin,

This is a good idea. It helps. The affects of moisture are more complicated though.  IF it was just mass it would be easier.  Draw weight and performance changes so much with the moisture.  More than just the weight of it.

Dan

[Badger]

Justin, pretty much as Dan said, the entire formula is performanced based and derived. Moisture control is one of the key elements even though some woods tolerate slightly higher or lower mc's than others. I have often felt that the best way to build a bow would be to overbuild it to start, make the best bow you can for the demensions you choose ignoring the draw weight. When you get all finished with your bow then just narrow the sides to attain the draw weight without affecting performance. I have done this many times with hickory that has a little higher than desirable moisture and it never fails they just come in far too heavy. Elm seems to hold on to moisture quite a bit also. Steve

[Far East Archer]

Steve,
I know exactly what you speak of, it mostly happens with my backed bows but also occurs with my selfbows. If I put in 6" of reflex in a boo bow and it looses half of that I can still bend it the opposite direction and it gains about 2" of reflex. I always worried that it could be a bad glue line until I tried it with a mulberry bow which had 11/2" of reflex and now has 1" of set. I wonder if its just the back of the bow trying to shrink and pull the bow into reflex and by bending it you are just speeding up the process??? Good topic !

-Alex

[willie]

Badger
 
I just read your recent comment in Beadmans thread....Inducing deflex/All reflexing

http://www.primitivearcher.com/smf/index.php/topic,57828.0.html

A bow that maybe only recovers 1/2" or so after shooting is better than a bow that recovers a full inch. If you loose 3" of that reflex and when you unbrace after shooting and it stays about the same you are good to go. The wood is still solid. Not all set is the same.

Question: do you make any conclusions from the speed of recovery, in addition to measuring the amount recovery?

Do you think that a bow that recovers less could have something to do with the four different types of set described in post 32 above?

thanks
willie

[Badger]

       I didn't read my original post because I know my views have changed quite a bit since I posted that. Intuitively I would sy the faster it recovers the better but anything that doesn't recover before the arrow leaves the bow is set. The only accurate way to check is really not worth the effort it takes, you need to shoot the bow through a shooting machine for an accurate speed reading and then take an accurate force draw curve to figure up your efficiency.  String tension right after the shot is a good indicator. Or simply brace the bow and weigh it at full draw then let it up and weigh it at full draw again. They should be the same or as close as possible.

     A couple of years ago I did a little study on how hysterisis is affected by set. I came to the conclusion that almost all the hysterisis is a product of set, even minor set which is unavoidable. If you were to test a bow at about 22" before it had taken even a whisper of set it will show very low hysterisis. This indicates that some of the recovery actually takes place durring the shot but not fast enough to deliver the energy to the arrow.

    I kind of stumbled on to a method of tracking the hysterisis. A fiberglass bow has almost no hysterisis. If you calculate the virtual mass of a fiberglass bow it is very predictable with almost any arrow weight. A wood bow shows higher virtual mass as the arrows get lighter which means it is not recovering fast enough to keep up with the arrow. The more consistent a bows virtual mass across a wide range of arrow weight indicates how low of hysterisis a bow has. But honestly it is such a pain to do the test that just knowing the theory behind it is really good enough.

[BowEd]

I did'nt join this PA till 2011 but through investigation could of looked this discussion up.I'm probably missing some point here but as far as I'm concerned a mushy type limb pushed either way after unbracing has lost it.A noodle.No strength.When push pull unbracing a bow a person can feel how stout a bow is if it has a little reflex on it.It's a little hard for my mind to get around all that was discussed.
Checking a bows stress level with a digital poundage tester pulling to full draw/release slowly and then to full draw again is a good way to test and I do that at least and pay attention to that.Extended periods of bracing causes the same thing to happen.A little slower but still.
Seems like most bows I make are'nt broke in properly till at least 200 arrows go through it and at least 3 to 4 hours of bracing time at one time is done a few times on them.Then the bows show what they show and pretty much stay with that profile for the rest of their life.Broke in.Until someone really overdraws it good and then it's really broke in......lol.

[willie]

Thanks Steve,
I am still trying to get used to the Idea you are suggesting, and if I understand you correctly,....

a small amount of recovery (in spite of larger total set taken)
is preferable to a larger amount of recovery, even if the bow doesn"t retain much set from where you started?

I keep a "short as possible" longstring on my bow during the early stage of tillering, and can sometimes see recovery by watching the string "return", (right after the pull), that would be hard to see by measuring at the limbs. 

[willie]

Ed
I like Steve's idea of watching string tension/early draw weight.

I wonder if anyone has seen or used a small digital inline scale that could be placed "in" the string ?

willie

[BowEd]

Well when a bow is on a short as possible long string a person can see the amount of poundage it takes to get the tips 6" past the handle after it's tillered would'nt you think?

[willie]

sorry for the confusion, Ed.  My fingers and keyboard cannot keep up with the flow of ideas sometimes.

I was thinking more about after the bow has been braced with a normal string. Perhaps it might be more telling to watch a scale in the string, immediately after pulling. than to detect a  weight loss on successive pulls.

[sleek]

Badger, I have a firm beliefe that there is no better bow wood than elm. I just wish I knew for certain the species of elm it is that does so well.

I have built one red elm bow before. It was 2 inches wide, 68 long and 40@28. It was so spongy i could push down on the upper limb and it would spring to brace. I could throw an arrow faster than it could shoot. I had a very similar experience with black locust before too.  No ammount of heat treat would get these bows to perform. I noticed something both these bows have in common, and something in common with my least performing osage. Ring count.

The ring count on the locust and elm were very low. Both bows had only two rings, with the early wood placed dead center of the limb. All my slowest osage bows have thick rings. All my fastest have higher ring count. Perhaps that can contribute.