Different kinds of set

[DCM]

I wonder if it's just different degrees of set, or if it literally manifests itself differently physically.  I have this theory, I think I stole if from Lennie although I won't have to admit it if he doesn't remember, that wood can compress and have permanent distortion without having crushed otherwise work capable wood cells.  I reckon the soft rings in ring porous (or even diffous porous) can be compressed leaving the summer rings undamaged.  As their ability to withstand compression is weaker, they will fail "first."  I reckon differences in species and specimen, the distribution of rings etc. could manifest itself in a good bit of variability in results with our projects.

[MattE]

Where in the tree you get your stave from is probably the biggest factor as to whether or not your bow will have excessive set.This is if the wood is handled properly and the bow is built right. Your bow is, as Steve said, okay! I bet it is a smooth shooter.

[Dane]

Dane,

The width profile of your bow in integral to it's analysis and hard to judge with just figures.  While no project is a failure, every project offers an opportunity to imrpove the next one.  Without seeing the width profile of you bow, I'd say you could have saved youself 1/2" or more of follow from having the limbs bend more evenly along it's limbs, towards the fades and/or mid limb to preserve this nice shooting manners, I would guess.  I love elm for bow wood.

Getting the limbs to bend more toward the handle is one of the biggest challanges for me personnally, and I would have liked to have done that this time. However, I want to keep it at 50#, and not shorten the limbs (66"), so I will probably call it done and finish it. No hint of stacking, and it shoots sweet and fast. Next bow, I'll do better.

I love elm as well. It works so well for me. I have another elm stave waiting to be worked on, and am thinking of tackling a Holmgaard (sp?). Gods help me,

[Dane]

Where in the tree you get your stave from is probably the biggest factor as to whether or not your bow will have excessive set.This is if the wood is handled properly and the bow is built right. Your bow is, as Steve said, okay! I bet it is a smooth shooter.

Thanks Matt. That is appreciated. And I don't know where in the tree the stave came from. I got this stave at the New England primitive meet last month. I'm writing an article on the event, so that will be forthcoming, if PA chooses to run it.

I have something really special planned for the finish on this bow, and I'm going to make a linen string for her, as well.

Dane

[Dan Perry]

Steve,

We usually look at set as the wood breaking down it compression.  There may be more to it than this.  Have we ever explored the break down of wood in tension? I believe that we assume that if the wood breaks down at all in tension that
the bow will come apart.  I am not sure this is true.  Also, set taken from wood being too wet seems to be different than wood that takes a set from exceeding its limitations.

Dan

[Badger]

Dan, that was exactly the answer I was looking for, I have suspected tension breakdown for a long time as being a reason for different behavior in similar looking bows. I have some bows that I can saw up, Splitting the limb down the middle might make this pretty easy to check. I don't always do the best job phrasing a question as I did here, the type of set or behavior of the rested bow, rather than the amount of set is what the question here is actually about. Steve

[George Tsoukalas]

Dan and Steve, that's good stuff. We were always taught that there's the belly and the back and  the line of separation between the two is the neutral plane. At least that's what the engineers taught us. I wonder if there is more interaction between the 2 than supposed. I don't know if a bow's back can cause set bit it can certainly cause breakage quicker. Jawge

[Badger]

Jawge, you work with black locut a lot, and I know you haven't had much problem with it chrysaling, Does it tend to take less set than other woods i general or would you say about the same? Steve

[George Tsoukalas]

Badger, I would say it takes about the same set as other woods. Jawge

[Justin Snyder]

This is an interesting discussion.  I know exactly what you are talking about Steve.  I have had bows that took set but were still firm and springy. You could bend them in either direction, but they would return to the same profile.  Then you have another that takes set and acts like lead.  You can bend it toward the back and it stays, you can bend it toward the belly and it stays. It seems like the bow is dead.  Justin

[tom sawyer]

Dan there might be a little "tension set" in a bow, but typically I think the majority of set is compression set.  Most woods have a much higher strength in tension, so typically you are operating well within the elastic limit.  Moreso than the compression side.

I envision normal set, as compressing the spring growth near the belly surface until it has a density similar to the surrounding summer growth.  That is why you see some set in most bows, and more set in a bow made from wood that has more spring growth.  You still get some set in backed bows using quarter-sawn wood, so there is certainly an element of set that works on the summer growth exclusively.  I've had better luck with quartersawn belly slats though, and I think the reason is there is summer growth throughout the full width.  The trick with summer wood, is to adjust the limb width so you aren't "counting" the amount of spring growth.

It'd be simple enough to put some set in a slat, and then cut it in half and see which part shows the set.  I've heard of people doing this, but haven't done it myself.  Mostly I've heard that the set shows on the belly side almost exclusively.

[Badger]

Lennie, I think you are missing the point of the post, nothing to do with how much set a bow takes but the kind of set a bow takes, there are worlds of difference in how bows take set even though they measure the same. Steve

[Justin Snyder]

Steve, what about damage to the early growth rings throughout the bow, back to belly.  I have had some hickory with early rings that were thicker and of lower density than usual. I bent one farther than I should have, and you could see the slippage between the solid, late growth rings.  Not enough to delaminate, but enough to make feel like a laminated bow with wet glue.  Not a colapse or crushing of cells in the summer growth, but a fracture in the cells of the early growth so they quit working. Still provided hysteresis and added mass though.  Justin

[PatM]

I find that woods such as Maple and HHB follow the string 'powerfully' meaning that they take that solid set that Steve describes. My theory is that the wood cells in these dense woods is very uniformly compressed and becomes denser as a result. Similar to a forgewood cedar shaft.
 I think this effect is even more pronounced in wood that is pressed into service before it was fully seasoned. Several of the bows I made in my early bowyering days were from quick dried HHB. Even those which took excessive set were very good performers when the wood fully dried. I think the wood is more prone to developing this optimum type of set when stressed in an optimal moisture content for this to happen. Perhaps 15-20%.
 I also tend to think that wood staying permanently stretched in tension is also a factor in inducing set. I once made a HHB bow that was finished and had zero set. There were some spots on the upper limb that had small patches of cambium remaining so I wiped the back with a moist towel and warm water and scraped it with a spoon tip. The bow was strung at the time and when I unstrung it the upper limb had developed a small amount of set. There is no way the moisture had penetrated the whole limb in the few minutes that took.
   Pat

[Badger]

Pat, I have experienced the same thing with both of those woods, too of my favorites. Elm is also one of my favorites but i have gotten that spongy set with more than one elm bow. Osage i have seen it several times.
Justin, you may have somethign there. I will start to try and be more concious of the process. I have had lots of problems with hickory, I seldom get the performance I want. I have always attributed this to moisture. Steve