What is considered acceptable set on a design/ material basis?

[Tommy D]

I wanted to start a thread that compared what people considered to be acceptable set from tillering, so I thought it would be useful if people just posted a bow design, material and what they would consider good, ok or poor in terms of how much set it takes.

For example, my bamboo backed, ash cored, Ipe belly in 66” long R/D profile with 1.25 inch width tapering to .5 inch at the tips now has taken 1.25 inches of set at the tips from its original unbraced side profile. It pulls 63lbs at 27”.

I have no benchmarks to go on - so am curious what others consider “benchmarks”... 

[RyanY]

This is largely a matter of opinion and has changed a lot over the years. Used to be that an inch or two of set was totally normal and sometimes preferred. These days you almost can’t find a bow that hasn’t been heat treated to prevent set or even gain reflex. Lower is better as any set is the breakdown of wood. Because it is breakdown of the wood I think the acceptable amount of set doesn’t vary much between designs or wood species. My thought has been that I want shorter bows to take less set and longer bows can take a bit more but saying it “out loud” here I have a hard time justifying any reasoning for that. For personal bows I like to shoot for less than 1” of set but I think it’s time for me personally to lower that as a goal to as close to zero as possible. Set is irrelevant to some as long as your arrow can hit your desired target and with enough energy for hunters.

[SLIMBOB]

I would agree with that mostly.  My early bows took more set than mine do now.  I'm focused from the start at limiting it to as close to 0" as is possible, with a reasonable width profile.  I have some that I came close to achieving that, and others that I didn't.  The less set, the better, and I focus on that from floor tiller to finished bow.

[Del the cat]

My bench mark (assuming a straight limbed bow).
Put the bow down on a flat floor belly down.
If the tips aren't touching the floor that is very good.
If you can get one finger between floor and grip that's good.
2 fingers ok.
3 fingers poor.
Del
(Assuming British standard finger )

[HH~]

Depends what you lose in the set. The only wood i have used that will take hunnerds of thousands of shots. Take some set and then put on form add some heat, seal it without any effect on weight and cast is good USA elm. Could build one hunt it yer whole life, get buried with it, they dig you up after ww3 in couple hunnerd years and your kin be hunting one horned glowing deer with it.

Happy 4th to you Patriots out there!

HH~

[scp]

All depends on what causes the set. If it is the "breakdown of wood", it cannot be good.

Willie mentioned the peculiar nature of wood.
https://en.wikipedia.org/wiki/Viscoelasticity
https://www.researchgate.net/publication/233069103_A_viscoelastic_model_for_the_compaction_of_fibrous_materials
I have no way of comprehending these articles myself.

Let me ask a stupid question.
Can wood be compacted, either temporarily or permanently, to become stronger?

[airkah]

My bench mark (assuming a straight limbed bow).
Put the bow down on a flat floor belly down.
If the tips aren't touching the floor that is very good.
If you can get one finger between floor and grip that's good.
2 fingers ok.
3 fingers poor.
Del
(Assuming British standard finger )

I measure straight limbed bows the same way and for recurves flip it over onto the back to measure reflex. 

[mmattockx]

Let me ask a stupid question.
Can wood be compacted, either temporarily or permanently, to become stronger?

The simple answer is yes. Recently I saw an article that described a procedure used to compact wood to a much denser state using chemicals to soften the lignin and then a press to squash the wood down. It was done for research into ways to make wood a better structural material for buildings, I don't know if it would make a better bow or not. The process was complicated enough that it is not a DIY type of thing.

If you care I can dig out the article and the research paper but I don't think it is very applicable to archery.


Mark

[scp]

I was thinking about a spliced bow with plenty of set, that means already compacted by the bending. Can it be re-spliced with reflex and make a stronger bow?

[Gimlis Ghost]

I don't know if it translates to wood but my first solid fiberglass bow got left strung in my truck gun rack for several months and took a terrible amount of set. Most likely due to being black and exposed to sunlight .
Performance was badly effected. It felt very sluggish and velocity was obviously reduced.
Only thing I could think of was to string the bow backwards when I wasn't using it and check it out every few months to see how much it improved. After a few years the set disappeared completely. I thought of leaving it in the sun as well but figured it might warp or not come back evenly. I usually leave that bow unstrung but occasionally string it backwards for a few days to reverse any tendency to gain set when in use. Its very snappy now, but solid fiberglass is never as snappy as a proper wooden bow of good quality wood.

Probably many wooden bows can't be strung backwards at all. The Mongolian and Turk horn bows certainly can't since when unstrung they form a C shape. The Scythians and perhaps the Mongols as well always carried two bows when on campaign. They left one unstrung and the other strung ready for use. They switched these out every day.

Some Egyptian bows had a lot of deflex by design, limbs were at more an obtuse angle than a curve. I suspect they wanted a minimum of stress on the limbs and if the bow got weak they could just shorten the string a bit as a stop gap measure.

[RyanY]

I was thinking about a spliced bow with plenty of set, that means already compacted by the bending. Can it be re-spliced with reflex and make a stronger bow?

The back would break before the amount of set needed to gain any strength in compression.

[willie]

All depends on what causes the set. If it is the "breakdown of wood", it cannot be good.

Willie mentioned the peculiar nature of wood.
https://en.wikipedia.org/wiki/Viscoelasticity
https://www.researchgate.net/publication/233069103_A_viscoelastic_model_for_the_compaction_of_fibrous_materials
I have no way of comprehending these articles myself.

Let me ask a stupid question.
Can wood be compacted, either temporarily or permanently, to become stronger?

About set that recovers after resting (Viscoelasticity).
If anyone has a tillering method that makes use observing this behavior to avoid permanent set, please share. I use a method on my tillering tree that seems to work, but it is hard to quantify.
BTW, some woods (especially conifirs) do this more than others

Bill Sweetland compressed bolts of Port Orford cedar 3:1 to make Surewood shafts with very high spines @ 5/16

[scp]

I was thinking about a spliced bow with plenty of set, that means already compacted by the bending. Can it be re-spliced with reflex and make a stronger bow?

The back would break before the amount of set needed to gain any strength in compression.

We are not stressing the bow enough to break the back. Are you saying that we need to stress the back more than its tension strength to "compact" it?

The back has already taken set and possibly "compacted" enough not to recover fully. Can this compacted limb be stronger than before, against our intuition? I am asking this silly question just because I have no idea how the "compaction" works in wood.

I am thinking about the effect of burnishing. Some say it does nothing, but some say it makes the limbs somewhat stronger by crushing the cells to be more "compacted", both in the back and belly. [paraphrased]. What if we burnished the limbs that have taken set?

Let me rephrase the question: Does this "compaction" in the viscoelestic material have anything to so with the set in wooden bow limbs?

[Don W]

If we think back to science class we learned that compressing a substance causes the molecules to speed up. Anything rubbing together fast causes heat.

I would guess the compressing wood (like the arrows) if you found the right compression rate at the right temperature for the right time would work. You're compression would cause heat(maybe helped by more heat, maybe not) which would fuse the molecules together making them stronger.

Burnishing on the other hand is fusing the outside fibers together. It's the same theory, just not as deep or as far reaching.

Set however is caused by compression at weak spots in the wood. It's like running over a 2x4 with a tractor. Even if small portions wind up fused together, they're split off from the "good" wood.

All redneck theory of course!

[RyanY]

scp, You can’t pull that bow back forever. Your hypothetical bow already has spongy limbs from set. Not only would that design cause early stacking, you’d continue to stretch the back causing even more strain. Eventually it’ll break before any performance gains from a compressed belly. Or if it never breaks it’ll be a dog.  It doesn’t make sense to use the motion of a bending bow limb to compress wood for performance advantage. Do it before the bow is bent and do it to a belly lam. Also, there still has to be some elasticity in compression to not overstretch and break the back.