Twisted limbs?

[bowmaster12]

I know its probably impossible to tell from pictures but... what do you guys see?  This is with the back up string that comes back to string geooves when shot.  But when drawen and let down string lays to the left of string grooves.

[McDave]

The limbs look pretty straight as photographed, but there is a more precise way of telling.  If you have the plastic limb centering gadgets, use those, or if not, you can use pieces of tape where you measure and mark the center of your limbs.  Put one gadget/tape on the belly side of one limb, and the other gadget/tape on the back of the other limb.  Put one limb tip on the floor, so that you can raise the other end up and down with your hand.  You will have to experiment with the positions of the gadgets/tapes until you can see both of them at the same time.  With the string in the center of the gadget/tape on the belly of the lower limb, the limb tip should also be centered on the gadget/tape on the back of the upper limb.  If the limb tip is off to one side or the other, you know it is twisted.  This is a very precise way of showing that.  I tried photographing this to show you, but the wide angle lens of my iPhone makes this so distorted that it is difficult to see both gadgets in the same photo.

What is the recommended brace height of your bow?

[Terry Green]

Sounds like a string loop issue, but I'm no expert on that.  I know lots of folks that only use endless loop strings instead of Flemish twist.  I'm not a target archer, but I'm pretty sure that's all most of them use.

[Kirkll]

Sometimes just the torque you put on the grip and the string when letting down can bring it out of the groove if its a bit weaker on one side.   The best way to watch the limb in action and check the tracking is to open up a door & hook the string on a door knob. then grab the riser and draw the bow towards you while watching the limbs bend. If its not tracking straight when drawing it, you will see it go to one side or the other.

You can do the same thing hooking the riser on the door knob and pulling the string back while watching the limbs bend. Flip the bow and watch the bottom limb too. This is called "Limb tracking".

I've seen some bows that have a slight tracking issue that come right back into the groove every time and shoot great like this for many years with no obvious limb twist ever developing. keeping the bow strung up for awhile is a good idea.

     Kirk

[Appalachian Hillbilly]

A lit of bows will not follow string groove if you let down vs shooting.

Not many people I know have a completely torque free straight  pull string draw...

Put an arrow under each limb/string area at brace height and if limbs are twisted, the two arrows captured under the string will not be parallel.

[bowmaster12]

McDave recommended brace is 7 3/8 - 7 5/8.  In the picture the brace is 7 1/2.  With the custome string made by the same maker that makes the string for the bower i can only get down to 8 inch brace.

[bowmaster12]

Maybe it's nothing to worry about it shoots where im looking.  Might be over thinking things

[McDave]

Since the string returns to the string grooves at 7 1/2, but not at 8, it would seem that there is a slight twist toward the end of the recurve, and the string is reseating itself into the string groove as it returns to the lower brace height.  If this is the case, you should be able to see it initially lie outside the string groove and then reseat itself if you set up the bow on a doorknob or something similar, as Kirk suggests, and slowly draw and lower the string.  Fortunately, 7 1/2 is within the recommended brace height range.  This is worth documenting, and reporting to the bowyer.  Perhaps nothing should be done now, but if the condition gets worse over time, it would be nice to have a communication with the bowyer that shows that the bow arrived that way, and that it is not something that happened later.

Assuming you don't want to do anything now, the test I recommended earlier should show if there is any limb twist toward the end of the limb, and very likely you could counter twist and correct this condition.

[Terry Green]

I agree that your may be tourquing on the let down, but you still have a problem with the main string when shot correct?

No, there is a lot of over thinking of equipment and performance in our sport, but you have an issue that needs to be corrected.

Stay with it and solve and we will all learn a little to help the next guy. 

[Flem]

So if the string returns back to the grooves when released, but not when let down, it sounds like operator error.
It's a whole lot easier to control pulling the string, than the control the string pulling.

[bowmaster12]

Correct Terry with the main string it does not return to the string groove when shot

[Kirkll]

Maybe it's nothing to worry about it shoots where im looking.  Might be over thinking things

If the recommended brace height from the bowyer is 7.5" and your issues are happening with a shorter string only giving you 8" brace. I would highly recommend getting a longer string.

There is typically a sweet spot in every bow that gives you optimum performance, with least amount of noise, and vibration.....Amazingly enough two bows of the same make and model may have different sweet spots too.

 What a lot of archers do not realize is that the lower brace height with a longer string gives you a higher string tension at brace..... I know that seems completely backwards, and a lot of folks think if a recommended brace is 7.5" , that 8" will be better..... Trust me on this one... This is not the case.   I've done some detailed testing with an in line scale while studying the pre load on different limb designs. I was pretty amazed myself....

Some bows are more sensitive to a half inch brace difference than others.      Food for thought....    Kirk

[Orion]

Pretty hard to torque the bow if you draw it and let the string down gently, but not impossible.  Regardless, I'm still thinking it's a twisted limb or uneven string notch grooves.  Yes, torque can cause the string to fail to align with the limb groove when the drawn bow is gently let down, but either of the other two scenarios are just as likely the cause. And, given that it appears to be only a slight twist, it's expected the string would pop back into the string groove at the end of the shot.  You've already noted that you can shoot the bow as is, but if you're not satisfied with the way it looks/behaves, check the nocks and/or counter twist the limb to straighten it out.   

A couple of other possibilities.  Sometimes the bowyer doesn't get the string groove in the exact center of the limb. If it's off, it can be widened a little toward the appropriate side. And sometimes, the bowyer doesn't taper the limb tip areas evenly, i.e., one side of the limb has more material than the other and thus it is stronger and bends the limb tip away from the stronger side.  The fix is to take down the stronger side a tad.  You want to be very sure that one or the other of these is the culprit before taking a file and sandpaper to the limb though. 

[Al Dean]

I had a production bow that had this exact problem.  Manufacture would not replace bow, so I never learned problem.  Sometimes I wonder are the string groves centered on the limb tip?  Although to me the bottom picture shows twisted limb.

[Kirkll]

Getting into WHY limbs twist could take up a whole chapter in a bow building book.  There are many more ways to screw up a perfectly good bow than you could imagine...  

Long bows are more forgiving to build with deep cores. You get into building recurves with an aggressive hook, and that gets a bit tricky at times..... But it's a seriously challenging good sport in itself.      Kirk

[bowmaster12]

Talked to the bowyer today.  He is pretty confident he knows the issue can't say for sure until he sees the limbs.  He is making me a new set of limbs and also letting me keep the orginal set for a back up of im ever in a pinch.