Author Topic: Is this a crack or scratch? (Read 468 times)

RodL · « **on:** February 12, 2016, 07:33:00 PM »

I was stringing my bow yesterday and noticed this mark, when I run my finger over the mark it feels smooth so I don't think its a surface scratch, any ideas what it might be?

Gdpolk · « **Reply #1 on:** February 12, 2016, 08:01:00 PM »

While I'm certainly not an expert but it looks more like a crack to me. It almost looks like it extends ever so slightly (maybe 1/32" or so) into the riser fades. Also, it looks a little too straight and parallel to the limbs to be a scratch. I don't know how you would get one to line up quite like that in this particular area.

« **Reply #2 on:** February 12, 2016, 08:19:00 PM »

Stress crack in the glass would be my guess. I'd suggest marking the end of it and keep an eye on it to see if it gets worse. If it does it may need some CA treatment.

bucknut · « **Reply #3 on:** February 12, 2016, 10:01:00 PM »

Stress crack for sure. Had a bow do this 20 years ago and I'm still shooting it today with no problems. Crack has grown a lot more but no adverse effects. As said before mark it at the top and watch it.

Possum Head · « **Reply #4 on:** February 12, 2016, 10:56:00 PM »

Yep I've had several do it at they keep on shootin. They are an eye sore however.

yaderehey · « **Reply #5 on:** February 13, 2016, 01:58:00 AM »

Can't tell from the picture but is there a limb bolt hole nearby? Almost all the glass cracks I've seen in limbs that look like that come from the limb bolts being tightened excessively. Either that or less frequently by the limb wedges swelling from excessive moisture and cracking the glass. As others have said no adverse effects normally. Don't crank too hard on your limb bolts.

flyguysc · « **Reply #6 on:** February 13, 2016, 07:50:00 AM »

Scratches are accidental which happen by chance.That is way to lineal to be a scratch. Looks like a stress fracture. It is to hard to tell from the poor quality of the pic.

RodL · « **Reply #7 on:** February 13, 2016, 10:05:00 AM »

Thanks for the responses, there is a limb bolt close to that area, I didn't think I was tightening the bolt excessively, I only tightened the bolt until it starts to get snug then stop, but maybe that's to tight for this bow. This bow is just over a year old and I have sent an email to the builder with more pics, I haven't hear back from him yet and have a indoor shoot this evening and was just wondering if I should shoot the bow or not. Thanks again everyone

Tajue17 · « **Reply #8 on:** February 14, 2016, 07:58:00 AM »

I had a couple bob lee longbows that did that,, I just kept shooting them and nothing happened other than dropping the value.

a luthier (builds guitars) who also owns a traditional archery store said they have an easy way to fix those and stop em from spreading they refill them similar to windshield repairs.

Tim Finley · « **Reply #9 on:** February 14, 2016, 11:27:00 AM »

It is a crack from moisture getting in to the bolt or alignment pin holes , the wood swells and raises causing the cracking. It will eventually work its way up the limb , it is something to worry about . The ONLY way to stop it is to overlay it with wood or micarta . It comes from not properly coating the holes with finish . When you draw the bow the threads from the bolt rub against the side of the holes in the limb and scratch the finish off or the alignment pin holes are not coated enough . I use a metal bushing in the holes and it has eliminated the problem .

**DONOTDELETE** · « **Reply #10 on:** February 14, 2016, 12:52:00 PM »

Well Tim....

I disagree with you on a couple things here.

I think you are correct that moisture content and swelling of the wood is partially responsible for the glass to split. But i think using a very thin super glue can keep it from running further in most cases without the use of an overlay.

When i say "Partially responsible" I mean that i believe that it may be the type of glass used too. There are two types of clear glass available to us made by Gordon glass, and most commonly used on bow limbs. One of them is "UL" & the other is "ULS" . The "ULS" glass has "Scrim" in it which helps reinforce the glass, and is much less prone to splitting than the "UL" glass......

Some bowyers believe the "UL" glass is less apt to have streaks or cloudiness flaws in it than the "ULS" does. Quite honestly i haven't noticed a bit of difference in clarity. but.... the "ULS" is much more resistant to splitting like that....

Using bronze bushings with "UL" glass is a good way to go, but unnecessary with "ULS" glass.

In reply to the original post: I would encourage getting some Loctite 420 in that split and let it set a few days in a warm dry place before using it. I would also keep the bow indoors in a warm dry place a week before doing it too to make sure the MC level is back down.

Sixby · « **Reply #11 on:** February 14, 2016, 05:10:00 PM »

What Kirk said plus I double locate pin my limbs and then lightly ream out the bolt holes and seal with Loctite which has kept any of my limbs from splitting. Little things like this I do because of my own experience as a bowhunter and problems with bows I have had in the past. Thin Loctite will pretty much disappear and stop that crack and do it as Kirk described and you should be good. I would also seal the bolt hole while you are at it and if you are double pinned then I would ream it out a bit before I seal it. I believe if you look inside with a flashlight you will find where the bolt is pressuring against the glass.

God bless and good luck, Steve

RodL · « **Reply #12 on:** February 14, 2016, 06:40:00 PM »

Thanks again everyone, a question for Kirk & Steve: You mention about putting Loctite in the split to possibly stop it from expanding, do I just put the Loctite over the crack from one end to the other? I'm not quite sure how to get the Loctite inside the split because I can't feel any difference between the crack and non cracked surface

Rodney

LostNation_Larry · « **Reply #13 on:** February 14, 2016, 08:56:00 PM »

Really, really glad you posted this. I have seen it and I like the recommended fix. I would put locktite on the end of the crack found at the limb bold hole and along the length of it, even if I cannot feel anything. But I am not a bowyer and would love to hear what Kirk and Steve have to say.

Tim Finley · « **Reply #14 on:** February 14, 2016, 09:13:00 PM »

Trust me I have delt with this before, numerous times on different makes and models I have been a commercial bowyer for 30 years. Super glue will not work ! I have even drilled tiny holes in the end of the cracks then filled the hole with glue and it didn't work either .You need to overlay it and if the cracks get too long it will just keep running up the limb. Loctite will NOT stop the crack I've tried it on several bows and it didn't work.

Sixby · « **Reply #15 on:** February 15, 2016, 09:14:00 PM »

I use a heat gun and carefully heat the limb from the opposite side so it draws the Loctite in. I use the Loctite Professional and lay a bead right on the crack. Warm the limb up pretty good before and then , moving the heat gun back and forth lengthwise from the opposite side. Most cracks will completely disappear. No argument here but I have not had any problems with the cracks continuing after doing this so my experience differs from Tims but respectfully. You do have to heat and you have to use the real runny glue.

Once again you have to eliminate the cause and relieve the area in the bolt hole that is pressuring the glass to start with. Without doing that what Tim said definitely stands.

God bless and good luck , Steve

Hud · « **Reply #16 on:** February 16, 2016, 01:06:00 AM »

Loctite 420 is extremely thin, a lot goes a long way, or all over your bow when it runs. Use 400 grit emery paper to roughen the scratch/crack and use one drop and a toothpick to spread it in the crack. After it dries you can sand lightly with 150, 200, 400, 600 etc. remove dust and spread a little True Oil over it. When dry hand spread a thin 2 coat. Repeat up to 6 coats or whatever your happy with. Use rubber gloves, and work over a safe protected area. It likes to run everywhere.

Put the top on the Loctite, tape it, put it in a plastic zip lock bag and in the refrig. or it will eventually dry out. Loctite 420 is a bit expensive, $20 +.

Tim Finley · « **Reply #17 on:** February 16, 2016, 09:54:00 AM »

The reason I drilled the holes in the end of the crack was to get to front of the fracture because you cant get super glue all the way to the tip, its not open it wont penetrate it . Even then the cracks went right through the holes and kept going up the limb. Its easier to overlay it and usually its a permanent fix nothing is permanent with super glue. If the crack is to long to start with as this bow maybe there is nothing you can do the crack will appear again even if its overlaid . I also found it to be worse on bows that had actionwood or that type of laminate material. Bamboo doesn't absorb moisture like wood and doesn't seem to have the problem . I'm done nobody listens to me !! HA

Sixby · « **Reply #18 on:** February 16, 2016, 02:53:00 PM »

Tim you are probably right in that Loctite is not the fix,. Its the combination of fixing the cause and then using the Loctite that works. The Loctite will seal the wood and keep moisture from getting in the crack plus it holds the crack together and fills it . Once the pressure is eliminated there is just no more causation for cracking.

God bless, Steve

RodL · « **Reply #19 on:** February 16, 2016, 06:35:00 PM »

I'm working with the gentleman who built the bow and probably going to get a new set of limbs and keep the old limbs to shoot and see what happens. Thanks to everyone that responded to my post, I'm going to try what Tim suggested and see what happens, thanks again to all

Rodney


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Author Topic: Is this a crack or scratch? (Read 468 times)

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