Bow Coming Unstrung When Shot

[Windsurfer]

Let me start by saying I am not sure if this is the correct forum.  I recently acquired a #52 1961 Bear Kodiak Magnum.  The hope was to add this bow to my collection and use it as a "hunter".  It was in bad shape cosmetically, but appeared structurally sound - no stress cracks or delaminations.  The bow does have some twist - when layed flat on a table and one limb is held down flat, the opposite tip moves about 3/8 inch when that limb is pressed flat.  There is no visible twisting in the limbs and they appear to be solid.

I removed the original finish and filled two small holes in the back of the bow just below the shelf and a little lower in the grip.  Then I decided to string it up and see how it shoots.  Since the bow did not come with a string, I took one off another K-Mag, strung it up and took a shot.  TO MY SURPRISE, the bow string came undone on the lower limb and slide up the bow.  I restrung the bow, double checked to be sure the string was on and in the grooves, and took another shot.  Same thing the string came undone and slid up the lower limb.  So, thinking the brace height may be to low, I took a different string from a 1967 K-Mag that I shoot every day and hunt with.  I strung the 61 and shot the bow with the same result.  

Does anyone have any ideas why this is happening?  I have been shooting and hunting with Bear Kodiak and K-Mags for over 40 years and have never had this happen before.  My only guess is that I need to use a much shorter string, say around 46 1/2 to 47 inches or the twist in the bow gets worse when drawn (my draw length is 30 inches) to the point that when the string is released the torque from the twist caused the bow to de-string the lower limb.  

Help would be most appreciated as this is a nice transition bow between 61 and 62.  It has a walnut riser, with purple heart sight window and a light outer lamination.  It would be nice to restore just for that alone.   Thanks,  Dave

[kuch]

Just some ideas : are the string loops too big for the tips? are the string grooves of the tips appropriate?  need to untwist the limb....your later statement would be correct by my guess, but not necessarily need a shorter string if brace is close.

I would closely inspect the tips and compare to your other K mags and untwist the limb

[johnnyrazorhead]

Dave- My guess is that you've got a weak lower limb that when pulled back it twists enough to allow the string to come out of the groove.I don't know if there is a cure for that.I've had a couple of old Bear bows in the past that the limbs laid pretty straight when the bow was strung but when pulled back one limb would "roll" to the side.Never had the string pop off but maybe it didn't twist as far as your bow is.Just my guess.

[vintage-bears]

Quote:
"or the twist in the bow gets worse when drawn (my draw length is 30 inches) to the point that when the string is released the torque from the twist caused the bow to de-string the lower limb:.


That's exactly what I think is happening. Hard to know for sure without seeing the bow in person.........Philip

[Windsurfer]

As noted, this is a late 61 transition bow to 1962.  The tips are very much like, nearly idential to two 1962 K-mags that I have.  Early 1961 bows that I have have much narrower pointed tips than this late 1961 bow.  These tips are very wide at the groove and pointed at the tip almost in the shape of an equilateral triangle.  Could the shape of the tips make that much difference in the size of the loops on a string?  Hard to understand how the strings work on bows with narrower tips and not on the 61.  

How do you remove twist in a limb?  

Thanks for all your comments.  Dave

[Trad-Man]

I can be as simple as twisting the limb in the other direction.  First though you need to have ssomebody else draw the bow so you can watch the limb.  Take a crayon and mark wher the limb is twisting.  You will easily see it if it is.

That said the closer to the tip the easier it will be.  Just twist the limb in the other direction.  Restring the bow and keep track of your progress.

If it is real bad you may need some heat from a hair dryer or a heat gun.  I've never had to use heat.  The Bow Doc cruises the forum.  Search his handle and send him a PM.  He'd know more than me.

[ksbowman]

It is because the limb is twisted. As Trad-man said you need to staighten the twisted limb. Try to do it without heat if possible use heat only  as a last resort, heat can sometimes cause more problems than it helps.

[450 marlin]

If you rub the 6-8" part of the limb with a cloth in your hand as fast as you can it will heat up nicely, then twist it the opposite way of the bad twist while holding the bow steady,,,hold until the bow returns to room temp. This usually works.

[Blackhawk]

Does it unstring ONLY when you shoot?  

What happens when you come to full draw and slowly let down?  

My guess is like the others that suggest your problem is a twisted limb and the remedy has been explained.  

Some will advise hot water, but I would not use that method.  

Also, if using an outside heat source, do not get the limb so hot it could compromise the limb integrity.  

Good luck...

[AALLFAB]

I have seen a problem in just one bow where the glass itself was debonded in the strands to itself detected by twisting the limb side to side and it felt like there was no strength or stability or stiffness at all. you could not see it but could sure feel it and there was no way to ever repair. We are talking a fluke here as this in a one in 5000 bows I have been through. Jim

[Windsurfer]

Based on suggestions I tried to remove the twist and restrung the bow. The string on the upper limb sets nicely in the notches and grooves on the belly of the bow. BUT, the lower limb does not align and set in the belly grooves. The tip is visibly twisted and when drawn the twist gets worse as commented.

Tried to twist the lower limb back into proper alignment with bow strung and this seemed to help. After a few hours tried to partially draw and the twist in the lower limb reappeared. The string does not come unstrung when released slowly but that was not from full draw.  

Jim, you may be on to something.  I have noticed that this bow does not seem to require as much draw strength as my #50 K-mag.  Maybe the lower limb has lost it's strength and stability as you suggest.  

CAN SANDING TO REMOVE original finish cause this to happen?  I sanded the original finish off down to the glass but did not remove material from the sides of the limbs.

Maybe this is just a bow to look at. Too bad as I have never seen a 61 K-mag in the walnut/purple heart I-Beam construction. Only other issue is two small holes in the grip. These have been filled and I am trying to find a paint to match the color of the glass. If I can it will really restore original looks and be very nice. If not, not sure what I'll to do with it.

[Kelly]

Sometimes with badly twisted limbs it may take sometime to correct them. When the bow is braced and string facing you place the twisted limb in your palm and grasped it so that the string is held in the groove while you are twisting the limb. Then go ahead and twist the limb in opposite direction of the twist. Twist it beyond what you think is needed as long as string stays in groove/palm of hand-then let it relax and check for straightness with the twisted limb tip on the floor, other limb tip on your chin-with hand at handle rotate bow right, then back to the left while watchingthe amount of limb tip that appears on each side of limb. If same amount on each side then rest the bow on two pegs at the handle. Leave this way for sometime-10 hours or so. Then take down and check straightness-if still straight then draw it, ;et down and check. If not straight do the process all over again till it stays straight. It can take several days on a bad twist. Also helps very much if the bow remains in a warm area-room temperature.

There is also a way to correct badly twisted limb by removing some limb material from the opposite side of the twist(I'm pretty sure that is correct) if the twist is in the recurve portion. After it is straight there might be a need to file thestring nock deeper on the side where you removed some limb material.

Frankly, don't believe you created the twist by removing the finish-would believe it was twisted when you purchased it. Did you shoot the bow before removing the finsih and did the string come off then, too?

[Windsurfer]

Kelly, No did not shoot the bow before removing finish but did notice twist.  Didn't string and shoot till after finish removed.  

I did hold bow with string in groove and twist limb to straight.  It seemed to help being strung, but after a couple hours I partially drew bow several times and twist returned.  That is when I sorta gave up.

Will try your suggestion to remove twist.  Thanks, Dave

[wadde]

Keep working that twist out, it takes time and patience especially on shorter bows.

[Windsurfer]

Time is something I have being retired from a career of environmental protection and living in Northern Michigan.  Patience on the other hand is something that I am still working on, hunting and shooting with a recurve instinctively is a great way to develop patience.  Thanks for the encouragement.

[Pack animal]

Hello Windsurfer
I have a dual shelf 64" 60# Polar.  It appears straight.  One day while shooting the string jumped off the upper limb and just like yours sslid down the limb.  The string was made for me by a local archery shop,but the loops looked large to me.  Again it only happened once when shooting.  The finish on the bow was it terrible shape so I sanded and refinished with Birchwood and Casey tru oil.  This past weekend it was ready to shoot; as soon as I strung it the string popped off.  I am glad you brought this up I was curious if it has happened to others.  I will also check the limb for straightness.
Thanks

[Windsurfer]

Pack,  

Not sure if lower limb of my bow is weak or what, but when drawn the lower limb twists very badly so that string pops off.  I have tried to remove twist but no luck.  Funny when bow is laid flat on table, there is no noticable twist on my bow.  Guess you never know till you draw.  Be Careful...