Longitudinal cracks in limb glass

[John R. Graves]

I recently pulled some old limbs, that I make years ago for a Bingham bow, out of storage and noticed a crack in the glass running 4 or 5 inches along the length of the limb. Can these be fixed with some CA glue or are they toast?

P.S. Disregard the brown Formica, that's the surface of my limb form. The bow limb is the black glass.

[Kirkll]

I suppose you could try the thin super glue, then sand it, and paint it flat black before finishing. Does that crack go clear to the butt of the limb?

[kennym]

Not sure how or if you can fix it, but what caused that?

Wedge take on moisture in bolt and pin hole? (I have a set of TD limbs that have never been shot that split from bolt hole like that because I didn't get any finish on them I guess.)

Rounded end on riser put more pressure there in center?

[John R. Graves]

Thanks for the replies. I may chalk these limbs up to experience. They're too heavy for me now anyway. Maybe I'll just use them for exercise. Gives me an excuse to get another set from Kenny.

[Kirkll]

Not sure how or if you can fix it, but what caused that?

Wedge take on moisture in bolt and pin hole? (I have a set of TD limbs that have never been shot that split from bolt hole like that because I didn't get any finish on them I guess.)

Rounded end on riser put more pressure there in center?

I think you are right about that rounded end on the riser Kenny... i didn't spot that. THAT would definitely do it. HUGE amount of pressure at that point.  those risers should be square ended, and rounded over a wee bit... Anything over 75# needs a thin G-10 plate, or a phenolic plate on the limb butts too to avoid over stressing the glass at that point. I lost a couple 80-100 pounders that way...    Kirk

[John R. Graves]

Thanks for clearifying that Kirk, I missed that in Kenny's reply. I will admit when I built this bow, I did deviate from Binghams blueprint, I thought it would "look cool". Live and learn, not sure what to do with that, squaring them off would make the limb pads pretty small. Any suggestions?

[Kirkll]

Thanks for clearifying that Kirk, I missed that in Kenny's reply. I will admit when I built this bow, I did deviate from Binghams blueprint, I thought it would "look cool". Live and learn, not sure what to do with that, squaring them off would make the limb pads pretty small. Any suggestions?

The only thing i can think of is removing the location pins and adding a flat G-10 overlay about 1/4" thick on the limb pads on the riser that squares it off again and redrilling the location pins.

Or ...... adding a thinner G-10 overlay to the limb butts....That might be simpler to do. i'd try filling that cracked limb with water thin super glue, then add a 1/16" G-10 overlay to the limb butts that extend past the riser tip a 1/4".

I would also recommend not doing that to your riser again...  Kirk

[John R. Graves]

Thanks Kirk. I think that I will square off the ends of the riser and laminate to the ends to restore the riser limb pad size, then reshape the riser to correct profile, if not G10 maybe some very hard wood or phenolic. Some rifle stocks have an ebony end cap on the forend. That may look pretty neat. You've definitely have given me some food for thought. Don't worry, lesson learned, I won't be doing that again.

[Kirkll]

If you need G-10 in small quantities, here is a source.

https://www.mcmaster.com/products/sheets/multipurpose-flame-retardant-garolite-g-10-fr4-sheets-and-bars/?s=g-10+sheets

Kirk