Deflex

[Kegan]

I asked a question about performance hindrances earlier, and got some help. From what I gathered, an under-stressed bow that doesn't weigh alot is a good thing . So...

Would putting in an inch of deflex (say on a hickory backed red oak bow) on a rather narrow flatbow (pulling 80# at 27", 1 1/2" wide in the middle two feet, tapering to 3/8" nocks, 70" long) be acceptable? The first good bow I made was a purposefully deflexed hickory bow, and it hit hard and fast- despite three inches of deflex and HUGE tips, and have gotten similiar testaments from others.

Thoughts? All but some of my most recent bows show about two or more inches of string follow anyway, so I figured, "what the heck"?

[Jesse]

One good benefit of deflex is it allows a high brace height also if you have a long draw it might help keep the wood from being over stressed. on the other hand it also shortens the power stroke to have a high brace and with only deflex and no reflex I would think the string would be looser at brace height.

[huntertrapper]

dont wnat to change the subject, sorry kegan, 1 quick answer.what exactly is string follow?

[Keenan]

Kegan, one of the main advantages to a D/R bow is to lesson the stress while braced. Also it is easier to brace whenyou only have to move the limbs a few inches. If a bow is braced all day as often is the case while hunting. A bow that is under less stress while braced is more likely to have the same poundage at the end of the day as it started with in the morning.
 Reaching the desired poundage is abtained with stiffer limbs, either by a traped design as with "reflexed and bamboo backed" or by heavier stiffer limbs.
  Brace higth dosen't have to be higher then normal, but can be if desired. I do feel you need some reflex near the tips to aid in string angle.
 The dimensions sound about right. I would do the deflex right in the handle if possible and a slight refled tip.  Go for it and at the very least your will learn more pros and cons.  Keenan

[Pappy]

hunter,it is when you unstring you bow and it is still bent like a strung bow instead
of flat or backset/reflex.An inch or 2 of string follow ant bad but something I strive not
to have if possable. 
     Pappy

[Ryano]

Deflex is no good unless you have reflex in another part of the limb to make up for the loss of early weight.

[Keenan]

 Ok food for thought here. If a bow has say 20 lbs of "early weight"  (Braced)  and is 60 lbs at 28" and another bow has 30 lbs of "early weight" (braced) and is the same 60 lbs at 28"  And both are hypothetically the same mass and power stoke and so on, just to elliminate the other factors.  Which bow will transfer the most energy to the arrow??? 

[Pappy]

The 2nd.
   Pappy

[tom sawyer]

The one with the 30lb of early weight will transfer more energy because there is more energy stored during the draw.

Deflex doesn't help performance, but if you have enough performance to do whatever task you want to accomplish then it really doesn't matter.  If your bow is pulling 80lb then there ought to be performance to spare, even with a less than hot-rod design.  The one thing I would observe, is if your design took 3" of set when you tillered and shot it in, then your wood was fatigued a little more than it should''ve been and it might be better to use a slightly beffier design (width, or length, or reduced poundage) to get better results.

The huge tips probably do negatively affect performance too, again you are compensating with the high poundage though.  And its tough to compare to other bows because every piece of wood and tiller is unique.

[tom sawyer]

I do agree with Ryan about reflex needing to accompany deflex for optimal performance.  Deflex near the handle means that mass of wood moves over a shorter distance, which reduces the work required to return it to brace.  Letting the outer limbs travel farther is OK because they are skinnier/thinner, meaning less mass moving the longer distance.  How much work is required to return your bow's limbs to brace position, is what determines the partitioning of stored energy between bow and arrow.  You total up the work required for each, then add these values and the percentage of each of the total, is your bow's efficiency.  For example, if it takes 30 work units to return your limbs to brace, and 60 work units to shoot the arrow, then your bow efficiency is 66% (60/90).

[adb]

Performance, for me, isn't the be all and end all. I'd much rather have a sweeter shooting bow, with less hand shock, and quieter, than a harsh, noisey bow that is 5 fps faster. Especially for hunting! A bit (2" or less) of string follow is a GOOD thing.

[Keenan]

 Ok just to challenge the thoughts some more. Support your decision.
  You both said the second. that starts with 30 lbs.   If you take 30 from 60 you have 30lbs being transfered to the arrow.  What is still stored in the bow at brace is not spent energy but is still energy stored in the limbs.  Now take the 20 lb braced from the 60 and you have 40 lbs of transfer to the arrow.  and only 20 lbs. left stored in the limbs.
  I know this is really tweeking some heads but is good food for thought. Ofcoarse the senario comes into play of what if you shoot a bow with zero lbs. of braced and we all know what that would do. But I'm challenging to do some thinking outside the bow here. If you had a bow of an incredible 40 lbs of early draw wieght but only went to 60 lbs. at 28"  basically 1lb. per inch how would you expect it to perform.

[JackCrafty]

The energy that is applied to the arrow is equal to the area under the f/d (force/distance) curve, not the difference between early draw weight and final draw weight.

[Keenan]

 Tim Baker once stated that if we think of things to the extream example then sometimes we can see what it is really doing. Thus my challenging questions. I do have my own thoughts or conclusions on this but am asking others to expound on the why's and theories so that everyone can learn and maybe even challenge thier own way of thinking.  Keenan

[Keenan]

For the benefit of others would you care to explain that Jack.