need screwup identified

[rockkiller]

Can anyone ID this screwup.I didnt use a saw to cut out the limbs ,I sanded them .I think I used a ton of glue .Dont know what those white spots in the glass are or if they are a problem.
Thanks for any help
Al
 

[Bowmonk]

Heavy grit sanding belt or disc cutting lateral to the limb. Resins become brittle and flake like glass. Think of how obsidian arrow points are chipped with such a small piece of copper or bone. Sand longitude to the limb with finer paper possibly?

[PZee]

Hey Al,

I have a similar problem, although I dropped my bow on a concrete step. Had a few stress cracks like that in the glass. I ran very thin CA glue into the cracks and the bow is just fine. Just drop the CA glue on the edge and watch the crack suck it up............ :-)

Thanks

Pete

[PZee]

Here's the link to my post...

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=009052;p=1

[Robertfishes]

I haven't seen anything like that happen. For grinding the limbs I use a 50 grit belt to grind close to the line and finish sanding to the line with a 120 grit belt..but I have used a 36 grit belt a few times and a 24 grit once. I am thinking you will have to wick some thin super glue into those places.

[rockkiller]

Thanks for the info.....I used 80 grit on a oscillating sander and took it right to the line.Maybe use a lighter grit next time.I did try some super glue and it didn't do anything.I'll try to find some real thin stuff.
Thanks again for the help
Al

[strungstick]

It doesn't appear to be the case in this instance but when you aggressively take the limb down with a sander you can generate a lot of heat and actually cause the glue or the moisture in the wood to boil out.  A lot of folks sand down a lot of limb just be careful with the heat generated.

[kennym]

I don't know, I have used a disc sander with  36 grit for many bows and never had that.

 

[JamesV]

Like Kenny, I use a disc sander with 36 and sometimes 24 grit with no problems. The corser he grit the less heat generated. Fine grit on a belt sander can generate a lot of heat.

[rockkiller]

After using cal and finnishing you can still the little buggers.After I got it to close to final shape I had to shoot it.I shot maybe 20 to 30 arrows.Is it possible that shooting before finishing caused this.    

Al

[Robertfishes]

I shoot every bow a few times before final finish is applied, just to make sure limbs are timed right.. In the bottom picture the white streaks are all running length wise, would that be fractured glass? did you have a hard time getting the bow out of the form?

[rockkiller]

If I recall right,it might have stuck a little,but not bad.

[kennym]

Robert may have it....

I've never seen it before.

[talkingcabbage]

I'm like Kenny and use the coarsest grit on a disc sander, and take it down pretty quick, and have never had that. Like Robert says, it looks like the glass is fractured. Was it ever twisted or maybe bent funny in a box or on a shelf? I've seen spots like that in clear glass before. The couple I had was on the end and I cut them off. But it went about halfway through the thickness of the glass and looked like a crack or fracture.

[rockkiller]

Not sure if it was ever twisted or bent funny.It was packed nicely . Around it self,like a rope,with some other things when it came in the mail.I have always received the glass like that.I cant remember for sure , but the package might have been slightly damaged.
So do you guys think it come apart or keep running?Guess I'll find out.

Thanks all you guys for the help.
Al

[kennym]

You might not have noticed the edge damage on the top pic, but I'm thinkin that other pc with glue spread on it would have been really noticeable.

[heartlandbowyer]

Rockkiller, maybe this happened before you even glued it up. I've had cracks that shower after glue up and I even inspected the glass prior to glue up. It takes a lot of pressure to cause that kind of stress fracture.

Another thought double check your form to make sure the surface didn't have anything on it.

Are you using tin pressure strips during glue ups?

Cory

[talkingcabbage]

That's a good idea Cory.  If he had even a small bit of hard glue on the edge or something, the pressure could've caused that during glue-up.  Mental note, double check the form before every glue-up.

[Robertfishes]

To help me make sure I have a clean, level and perfect glue surface.. when I make a new form I glue a piece of 040 black glass onto the form surface. I clean the fiberglass form surface before glue up with a razorblade, then I apply paste wax to it. I also clean and wax my galvanized metal pressure strips before each use..you can never be too clean or careful. I carefully brush all laminations with a clean stiff bristle brush and make sure there are no splinters on the edges of my tapers and veneers..lots of loose fibers and little splinters on the edges of lams, light sanding with a sanding block with 120 grit paper cleans the edges up pretty good if needed. 60 psi of pressure would likely compress these tiny pieces but I feel better if they are not there.

[rockkiller]

I checked the glued down piece of glass on the back side of form and the metal strips and didn't find anything obvious.Maybe there was something on it when I did the glue up.    It is a new form and I did wax it.I guess its just going to stay a mystery,but I am going to watch real close on the next one.
So what do you guys think will happen,Delam,crack more,or will the bow just blow ?