Can string follow be reversed?

[Leo L.]

Say you left your bow strung, and it took on some string follow.  Since the bow is finished, can the bow be put onto a form and heated to apply some back set?  Would the finish have to be taken off?

[bigcountry]

Be careful.  I took a yew english bow off the tiller tree.  And decided to turn over and push on the back a tad to remove follow frem being on teh tiller stick and she blew up on me.

[Leo L.]

:eek:    :eek:  

Not good!

[tim roberts]

I am not sure, made a learning mistake on my first bow that caused the limbs to be real narrow, by the time I got to tillerin' it I could see that I would have string follow in it, and was wondering the same thing.  I figured that since I had already started teachin' the limbs to bend, heating it and making it go the other way would be a sure receipe for disaster.  The bow came out a bit heavier than expected, shoots great, and I learned a ton getting it done.  Time to start a new one!!!!

[Bjorn]

You can get most out with a heat gun-like the one for scraping paint-how long will it stay out? Who knows.

[John Scifres]

Set is caused by crushing belly wood.  Assuming the wood was dry, it's probably permanent.  Sometimes wood that is crushed when wet can be brought back some.  You can certainly heat it and get some backset into it but the damage is still there and it will probably go right back.

Think about it like this.  You have 2 planes (or layers) that do the work in a bow.  

The back stretches during the draw and then returns to it's previous state depending on how elastic it is.  Once the wood is stretched beyond its ability to stretch, damage occurs and the wood can pretty much never be the same.  This isn't too common in most woods because they are almost all stronger in tension (stretching) than they are in compression.

The belly compresses and then returns to its previous position depending on how resistant it is to crushing.  Once the wood is crushed, damage occurs and the wood can pretty much never be the same.  

There are exceptions and some heat treating, depending on how hot and plastic you can get the cells, can help.

How much set are we talkin' here?

[Art B]

Brad Smith had a thread over on the Wall that touched on this subject.......but with a different twist. He took a friend's bow that had to much set in it and cut the handle out using a fishtail splice and then he glued 'er back together with the desired backset. Very simple.

ART B

[ranger 3]

I have a Osage bow that I toasted the belly and while it was hot I put it clamped flat on a 2x4 and let it cool. It has worked so far but you have to let it rehydrate for at least a week, putting in the bathroom would help. It also  added about 5 or 6 pounds.

[gordonf]

Once the belly is crushed it is permanent. The only way to "fix" it is to remove the damaged belly wood which, of course, will cause your bow to loose weight. Adding more backset will stress the belly more and likely reduce the efficiency of the limbs. I've not had much luck using heat to correct set - the effect is temporary and the limbs will eventually return to their pre-treated state.

[Chuck Hoopes]

String it backwards, heat treat, whatever-- the effect is temperoary.  Crushed cells, are like broken eggs-- you can't put them back to------again.  I think bending back and forth, can have the similar effect bending a piece of wire back and forth.--it weakens it further.  Live w/ what you have,  some string follow is not necessarily a bad thing.   Or as gordonf says,remove damaged belly wood-- If bow is too light to your liking,after this - Pass it along to someone who would like it -- and enjoy building the next one--a bit wiser.  Ive found it is  actually more fun to watch someone enjoy a bow that you have made, than to shoot them yourself,- even the ones that do suit you.  Just another way to enjoy these home built bows.

[Leo L.]

My situation was a hypothetical, and hasn't actually happened to me....yet.  Not saying it won't either.  I am working on my first Osage stave, and not even near floor tillering yet.  I was just sitting here, reading the threads, and some other internet resources and started pondering...WHAT IF that happened.  Could it be undone?  

I actually found the answer to my question earlier today while reading "The Bent Stick" by Paul Comstock.   I can post an excerpt from the book tomorrow as I left it at work, but basically what he said that you should never try to induce a backset on a stave that doesn't already have it, simply because the back was meant to expand and the belly to compress (exactly what John Scifres was saying).  

After reading a good portion of Paul's book today, I've got a pretty good understanding of how this stuff works now.  


My stave...it's got some natural backset on one end.


 
 

[Mike Byrge]

Leo,
Being in S.La (high humidity) you really need to build a drybox and get a humidity meter.   Once you get that bow to the floor tillering stage keep it in the dry box.

I made probably a dozen very average bows until I started using a dry box and the difference was dramatic...less set, faster, etc.

There is just no way to naturally dry wood in our climate.

[Mike Byrge]

but basically what he said that you should never try to induce a backset on a stave that doesn't already have it, simply because the back was meant to expand and the belly to compress  

I agree if the wood has taken a set due to poor tillering, compression, etc. but on a piece of wood in the floor-tillering stage I pretty much always use a caul and heat-gun to induce some reflex.

[ranger 3]

In my post I forgot the mention that after it rehydrate I scraped the 5#'s off and maybe that helped.

[Leo L.]

Here's that excerpt I mentioned earlier...


 

[John Scifres]

Most of what I learned about making bows and wood was from guys like Paul.  I'm mostly a parrot with a bunch of practical experience in not listening.  We learn by doing, and in my case screwing up  

Brad's ideas are very valid.  There are other ways of making a set bow better.  Removing crushed wood and shifting the planes is the best because you are starting with fresh wood.  You can bring weight back up by adding something like sinew to do the tension work.

[George Tsoukalas]

I've had a little success mitigating set by adding some reflex to areas that don't bend. Good candidates are the handle area by adding some set back and reflexing the last 8 inches or so. Keep the wood dry, tiller well and never  pull the stave beyond what it takes to expose a problem. Jawge

[Mike Byrge]

Leo,
Been awhile since I've read "The Bent Stick"...I know I used the heck out of it when I first started making bows.

I'm not gonna be so bold as to disagree with Paul Comstock, but I will say that I could take Stave B in the picture you posted above, use a heat-gun/caul to give is some reflex and make a nice bow that wouldn't follow the string any more than Stave A.

You'll probably want to straighten the piece of wood you've got so you might as well put some reflex in the other end while you are at it.

I would avoid Stave C unless it was the only wood I had.

[razorback]

When a bow develops set/string follow, caused by damage to the belly, how deep does this plane go. What I want to know is does the dqamage only occur in the immediate layer of wood, a 1/16th" deep, an 1/8th" deep etc. I know it will be different from bow to bow, but does anybody have an idea.

[Leo L.]

Mike, thanks for the tip.  I'll probably end up doing just that.  This is the stave you gave me last June at the Primitive Expo.  Yea I'm still chasing that ring, it's whooping my butt.  I've been using scissors mostly to scrape, and a scraper set as well.  That draw knife there was too sharp and was splintering the wood.  I want to finish this bow by season opener.