Set and hackberry

[Joec123able]

Gott a hackberry bow just about to be finished up. Directly after shooting a few arrows through it it shows about two inches of set, does this seem except able for hackberry that started perfectly straight? After sitting a few hours it shows about 1 1/4. Also I have only done some light heat treating to it I'm about to go do another heat treat but alittle heavier this time

[k-hat]

depends a little on the design of course, but yes, hackberry takes more set than many woods.  it benefits greatly from a good deep tempering.  At this point you may be stuck with the 1-1/4" of set (which is actually not bad at all!), but at worst additional tempering will keep it from getting worse, will add some weight, and make it a little more snappy (depending on how shot in it is).  But you should be able to give it a good deep tempering over a reflex caul and reverse it.  Will need some retillering.

There's more here:  http://www.primitivearcher.com/smf/index.php/topic,39331.0.html

[Joec123able]

Thanks. I'm just gonna leave it alone as long as the bow isn't to sluggish than I don't mind a little set

[smoke]

I've only made 2 bows of hackberry but I heat tempered the limbs of both with great results.  I've found hackberry to be a great bow wood.

[DarkSoul]

I've never worked with hackberry (doesn't grow in Europe naturally), but I think the statement "hackberry takes more set than many woods" is not quite valid. I'd like to comment on the general issue with a bow taking set. Most of my points hold true for any wood.

A bow doesn't take set by itself. The set is caused by something. It can be caused by one thing or several factors that get combined. Set basically is the manifestation of an overstressed piece of wood. Yet one wood can take set more easily than other woods. Possible reasons could be:
- Hackberry is a lightweight wood (low SG) and thus, is easily overestimated. A wood with a lower SG requires a wider limb design to deal with the stresses. Woods with a low SG (such as hackberry) tend to be made too narrow, and are thus easily overstrained, resulting in set.
- A wood can be compression weak, or tension strong (what's the difference?). Set always happens in the belly of a bow, not the back (see experiment with a bow with set sawn in half lengthwise). Therefore, the belly can become overstressed in compression weak woods more easily. A trapped back will counteract this. Heat treating the belly will also work, as this increases the compressive strength of the wood.
- A wood can require a low moisture content for optimal strength. Hickory is a good example. With a high moisture content of the wood, it tends to get set easily. While at a low MC, it is an excellent performer. Perhaps hackberry also likes a low MC. Any wood will take set more easily at a high moisture content level, but the optimum is different for each species.
- A wood can be more elastic than average. An elastic wood results in a lot of permanent bend (=set) before the wood fails. A wood with low elasticity just snaps, before taking any set. Therefore, hackberry could be a very elastic wood, that takes a lot of set before it finally fails. Jatoba, padauk, cherry and bubinga are some examples of (tropical) woods with low elasticity. These species chrysal and break, before they take a lot of set.

I hope this clarifies why a wood takes set and in which category hackberry might fall.

[Joec123able]

Yea i think your right about hackberry you have to be much more carefull when tillering compared to Osage the last few bows I made have been Osage and it seems like you can dog it and it still won't take set but hackberry you can't do that

[k-hat]

Seems to me "takes more set than many woods" is equivalent to "can take set more easily than other woods."   

Even Tim Baker in TBB (forgot which) says of some whitewoods: "takes set without much excuse."  Yeah if you're a master and tiller perfectly, and keep it extra wide, you can avoid most of it, but most of us aint masters tillering perfectly.  I would think the width you would have to make hackberry to have "no set/low set" would result in a below average bow (or at least below the potential of hackberry).  Hackberry simply performs best when it has been heat treated well which will allow you to take advantage of its superior tension and elasticity properties.

Joe you're right on osage, it can take some mistreatment and do well.  Hackberry does like a little more tlc.

[Joec123able]

I really like hackberry but just takes alittle more babying than Osage so that gives Osage an upper hand and makes it basically my favorite wood