How to measure set

[George Tsoukalas]

I agree with DWS. Jawge

[bassman]

If your finished unbraced profile comes out 1 inch of reflex for an example, and you string the bow ,and shoot it a bunch, and then when you unstring the bow, and it springs back to it's original profile right now then you have built an excellent bow, and in my opinion that is what you are looking for. Some of mine do ,and some don't. Some of my bows will take 20 minutes to a half hour to come back to original unbraced profile. If you lay the bow on a table you can watch the limbs slowly come back to it's original shape.

[bradsmith2010]

PatM,,,, good point

[bownarra]

Another thing which people new to bow making seem to get stuck on is trying to make wooden bows with loads of reflex....there is absolutely no need to heat bows in excessive reflex, thinking that you are going to increase performance.
A bow that had say 5 inches of reflex initially, tillered out it sits at 1" reflex = 4" of set
Another bow that was straight to begin with and only took say 3/4" set
Which bow do you think will perform better?
The 2nd bows belly wood hasn't been over strained and is therefore in better shape to take compression and more importantly its return speed after being compressed will be higher. After all set is permanent deformation of the woods cells on the belly. IF you can keep this damage to a minimum you WILL have a better bow.
So my advice is to begin with do not heat in more than say 2" maximum of reflex. 1" would be better. Aim to have a straight bow after tillering. The bow will be easier to tiller, will be less strained overall and you save all the headaches that lots of reflex can cause!
KISS is a great motto when it comes to learning bow making  

[bradsmith2010]

shooting a bow through a chronograph,, takes out alot of the speculatioin,,

[Badger]

    I agree with several of the posts above about starting with less reflex. Set carries hysteresis with it. It may be impossible to accurately measure set because I also believe there may be some pull out involved that is not really set. I tend to ignore early set on a heat treated bow. Best indicator of how much set your bow is taking that I have found is to see how much it comes back after unstringing. The less the better. I have had bows that will comeback as much as 3" if thy were highly rel-flexed, none of them I would consider fast shooters. I usually start with about 4" heated in just off the cawl before bending it might be about 3 1/2, after shooting the bow in if I can get 2" reflex as soon as I unbrace I am pretty happy as long as it doesn't gain back more than about 1/2" after sitting.

[darinputman]

Azmdted I can not even begin to answer the question about what would be the proper way to measure set. I figure there are lots of opinions on this and lots of variables also. I do enjoy reading everyone elses opinions though. I have made a few hickory fire hardened bows using the same process as you. I now try to take it as close to a finished profile as I can thus creating a lot less stress on the wood during tillering and have been very pleased with the amount of reflex I was able to retain. I have also pushed it too far and came in under weight on bows by doing this. When it does work out the tillering process is very short compared to my past bow tillering. I love being able to keep as much reflex as I can in a bow, that is one of my main goals besides good tiller. I just made a new caul for a bow I'm working on now, I just like to see how much I can keep and how the bows shootability reacts. Its all part of the process for me.

[bradsmith2010]

  ok if you have two bows roughed out from same stave...they are the same mass weight at this point, and straight0
you make the first one, no heat,, and it comes in 50#@26 and has one inch follow,, or set or what ever you want to call it,, the tips are 1 inche behing the back when unstrung,,
   now the second stave you heat reflex into the whole bow,, bout 3 inches,,
   you tiller it out and its holding one inch reflex in unstrung profile,, and the mass weight less than the first bow,,
so you have a bow 50#@ 26 with the tips one inch in front of back of bow that has mass weight less than the first one,,
   
    my experience tells me the second bow gonna shoot harder,,
   

[bownarra]

  ok if you have two bows roughed out from same stave...they are the same mass weight at this point, and straight0
you make the first one, no heat,, and it comes in 50#@26 and has one inch follow,, or set or what ever you want to call it,, the tips are 1 inche behing the back when unstrung,,
   now the second stave you heat reflex into the whole bow,, bout 3 inches,,
   you tiller it out and its holding one inch reflex in unstrung profile,, and the mass weight less than the first bow,,
so you have a bow 50#@ 26 with the tips one inch in front of back of bow that has mass weight less than the first one,,
   
    my experience tells me the second bow gonna shoot harder,,
 

Good luck but my experience tells me that you can't make the two bows you just mentioned. The one that held the reflex would have to be thinner and or wider. Being thinner and wider it will have less return speed. Rarely do we see wooden bow makers mentioning that thicker is quicker anymore. Think of tuning forks does the thicker one have a higher note?
Bow making is rarely as simple as it may initially seem
Another problem with your experiment is that you would be comparing apples to oranges if one is heat treated and one not. What I was talking about is how much set the excessively reflexed bow will take getting to full draw. That set isd killer to performance. Whereas if a bow was heat treated BUT NOT given an induced reflex and takes less set getting to full draw, thus keeping a straight profile AND not having the belly fibers getting crushed I know for a fact that the 2nd bow will be in much better shape as a long lasting durable bow.
I gave up on excessive reflex in wooden bows about 6 years ago after chasing it for years and have made better bows since. I've made a few real screamers (chronoy tested!) over the years and none of them where heated into excessive reflex.
Now if we use different materials that have the elasticity to take the extra bending eg horn/wood/sinew composites then yes chase the reflex! However it is only a part of the picture

[mmattockx]

I gave up on excessive reflex in wooden bows about 6 years ago after chasing it for years and have made better bows since.

So you stick to your suggested 1"-2" yourself?

Has anybody ever chronographed a flat bow, then heated some reflex in and chronographed it after? Results?


Mark

[bradsmith2010]

a straight stave bow with one inch string follow is pretty basic,,moderate design,,
a straight stave bow,, holding 1 inch reflex is pretty basic too,,,,
if you take a straight stave bow,, and test it,,
then heat treat it,, with some reflex,not excessive as suggest, the weight will usually go up,, and require retiller to get back to original draw weight, the performance can be inhanced,, the bow having less mass,, and some reflex,, at the same draw weight,,
its pretty easy to test it as suggested,, ,, the increased draw weight will add to the original arrow speed as well,,, if not re tillered,,,

[Badger]

      The bow that launched a broadhead for me the the furthest was the same bow I had at mojam, It was a straight bow not heat treated per say but heat straightened. I think I shot 231 at mojam and have hit as far as 238 yds in practice sessions. The only thing unique about the bow is that it took no measurable set and when measured immediately after unbracing it will still measure the same the next day, it has maybe 1/2" reflex. I think keeping set to a minimum is the most important aspect of bow building. Adding tones of reflex hoping to keep a little is very damaging to a bow.

[PatM]

I don't think the theoretical bow Brad mentions would react quite like Mike says.  That seemed like a more moderate scenario not actually requiring  wider thinner limbs.
  The two bows could still be  relatively narrower and thicker.

 

[willie]

      The bow that launched a broadhead for me the the furthest was the same bow I had at mojam, It was a straight bow not heat treated per say but heat straightened. I think I shot 231 at mojam and have hit as far as 238 yds in practice sessions. The only thing unique about the bow is that it took no measurable set and when measured immediately after unbracing it will still measure the same the next day, it has maybe 1/2" reflex. I think keeping set to a minimum is the most important aspect of bow building.

I usually start with about 4" heated in just off the cawl before bending it might be about 3 1/2, after shooting the bow in if I can get 2" reflex as soon as I unbrace I am pretty happy as long as it doesn't gain back more than about 1/2" after sitting.

Steve,  are the bows you mention above both built for the same purpose?

Adding tones of reflex hoping to keep a little is very damaging to a bow.

I suppose one always hopes to keep every bit of reflex , and at best, can only be disappointed to lesser degree when tillering    . 

But, this begs the question of how often do you get a bow that starts with 4" off the caul and doesn't gain back more than 1/2" after sitting?

[DC]

      The bow that launched a broadhead for me the the furthest was the same bow I had at mojam, It was a straight bow not heat treated per say but heat straightened. I think I shot 231 at mojam and have hit as far as 238 yds in practice sessions. The only thing unique about the bow is that it took no measurable set and when measured immediately after unbracing it will still measure the same the next day, it has maybe 1/2" reflex. I think keeping set to a minimum is the most important aspect of bow building. Adding tones of reflex hoping to keep a little is very damaging to a bow.

I agree in principle and it all makes sense but with my boo backed yew it seems that the more reflex I can get it to keep the faster it goes. If I lay out the last ten  or so bows in order of speed the one thing that sticks out is the increase in reflex. It's not a lot of increase, maybe a foot or so per bow. It could be improved tillering but I don't think so since I've had to put new bellies on a lot of them to correct where I've gone too far