Anyone id this defect?

[Radmcg]

Hi Guys first post.  Been building bows for 25 years.  Some good.  Some not so much.  This is an old set of limbs I laminated using Bingham style press.  I have made 5 to 6 sets of limbs with this mold and this is the only set that has done this.  The reason its important is I Carved a nice riser(for me) and liked it so much I made a second set of limbs for it.  The second set came out at 59# (target 50).  This set of limbs is exactly 50# but they look like this.  Any idea what caused this?  I have taken a loop to them and it doesn't seem to be splintering or delamination.  I have tried to pry the lam off and it is stuck fast.  The defect seems to be cosmetic.  The upper limb did the same thing just to a lesser degree.  If anyone knows what caused this please let me know as I am about to try a third set of limbs.

[kennym]

Are the tips close to the heat source?  Wonder if they got overheated in the heat box?

[Mad Max]

How did you sand/file that end FLAT ??

[Radmcg]

Never thought about the heat Kenny.  Good idea.  The sanding was the my first thought  MM.  But it doesn't seem to be delaminated or splintered.  It's just discolored under the fiberglass?  Both are possibilities though.  The heat makes since but the other limbs haven't done that.  I might have placed the tip to close to the heat source for the overlays though.  That would make since.  I will check and see if the next set come out of the box that way this time and be extra careful with the rasp when filing.  Its a real shame the 59# limbs are the best I've done.  Maybe I just need to work out more:). At least I know how to make 59# limbs.  Now if I can just make a perfect pair of 50# limbs.  The thanks for the ideas.

[Kirkll]

The discoloration is probably just the glass itself. I've seen it do this before.... Just paint the tips black, and call it a day. 

Ya might want to round over those tips a bit and round over the tip notches going into the belly side of the limb a bit too. Those sharp edges are hard on strings.

[Radmcg]

Thanks guys.  Yea I know the slots are rough.  I actually never finished these due to the defect.  Was digging in my hot box and found them.  I was going to work on them but put them on the bow and they only pull the 41 pounds.  Don't think they are worth the effort.  The good news is I found 2 complete sets of 72 laminations and bow tuff from Bingham's.  Looks like curly maple and a set of zebra wood not sure.  Old dudes should not dig into stuff they haven't seen in years.  Now I have to build 2 more longbows:)

[Kirkll]

Seriously… if you are concerned that glass might have lifted at the tip a bit you could try using a water thin super glue on the edges and see if it wicks under the glass. But….Considering it’s on the belly side of the limb, and just the very tip, besides aesthetics, it will never be a problem.  Put a thin overlay on the tips , or paint it black… there really isn’t a structural issue here.   Kirk

[Radmcg]

Thanks Kirk.  I might try that.  then paint the tips.  Maybe just camo the limbs they are nothing but Actionboo laminations any way.  At 41 pounds might make a good fishing bow.

[Tim Finley]

You should put some smooth on on the tip and work it in from the side with your finger it will go in almost all the way you have to keep working it  then clamp it the clamp will squeeze the glue in further . This is cause by not getting enough glue at the end of the bow limbs during glue up.

[Horsey]

The milky coloring of the fiberglass is definitely due to the tip being too close to the heat source.  I had the same issue years ago and had the exact same results. I changed the position of the tips on future cooks and solved the problem.  When I am heat curing tips and overlays, I use some "mini" ovens that only heat the target area and not the entire bow.

--Mike

[Radmcg]

Thanks Mike that makes perfect since.  IIRC I used a heat lamp for the tips and it was on the belly side of the bow which would have heated that side unevenly.  What does your mini oven look like?  Which brings up another question.  Is heat cured smooth on EA-40 any stronger than Epoxy cured at room above 70 temp?

[Horsey]

My mini-oven is a plywood box open on the bottom and notches on each end for insertion of the bow limbs.  The box is about 12" X 20" X about 20" tall.  The heat source is a 40 watt bulb at the top of the box.  I used a piece if sheet metal for a heat shield below the bulb.  To cook a tip, I just insert it in one of the notches so only the tip is in the box.  For handle overlays, the entire box sits over the riser with the limbs protruding through the notches.  I put a layer of foil backed insulation under the box.  It is kind of crude, but it works well. 
In my opinion, heat cured smooth-on is much stronger than any epoxy cured at room temperature.  I have used this method on hundreds of bows without a single failure of a tip or overlay.

--Mike

[kennym]

A bit less heat on overlays for me if any, if they come off you can put them back on, but if you overheat and weaken the epoxy in the limb, you pretty much done.

The overlays most times aren't working limb...

[Kirkll]

My mini-oven is a plywood box open on the bottom and notches on each end for insertion of the bow limbs.  The box is about 12" X 20" X about 20" tall.  The heat source is a 40 watt bulb at the top of the box.  I used a piece if sheet metal for a heat shield below the bulb.  To cook a tip, I just insert it in one of the notches so only the tip is in the box.  For handle overlays, the entire box sits over the riser with the limbs protruding through the notches.  I put a layer of foil backed insulation under the box.  It is kind of crude, but it works well. 
In my opinion, heat cured smooth-on is much stronger than any epoxy cured at room temperature.  I have used this method on hundreds of bows without a single failure of a tip or overlay.

--Mike

Most bowyers use CA for their tip overlays. That whole epoxy thing with a hot box for simple tip overlays is over kill and a waste of time..... and isn't any stronger if done properly with CA.... .02 cents worth.

[Jeff Freeman]

Smooth - On doesn't need heat to set or cure, for overlays. JF

My mini-oven is a plywood box open on the bottom and notches on each end for insertion of the bow limbs.  The box is about 12" X 20" X about 20" tall.  The heat source is a 40 watt bulb at the top of the box.  I used a piece if sheet metal for a heat shield below the bulb.  To cook a tip, I just insert it in one of the notches so only the tip is in the box.  For handle overlays, the entire box sits over the riser with the limbs protruding through the notches.  I put a layer of foil backed insulation under the box.  It is kind of crude, but it works well. 
In my opinion, heat cured smooth-on is much stronger than any epoxy cured at room temperature.  I have used this method on hundreds of bows without a single failure of a tip or overlay.

--Mike

Most bowyers use CA for their tip overlays. That whole epoxy thing with a hot box for simple tip overlays is over kill and a waste of time..... and isn't any stronger if done properly with CA.... .02 cents worth.

[Kirkll]

That would work too, but it’s still over kill… you don’t even need to wait overnight. This stuff dries and holds very quickly. You can do a set of overlays,  both limbs in an hours time no problem.

Here’s how I do mine. 

[Radmcg]

Thanks Kirk.  I take it that Bowyers CA has a longer working time than regular CA?  Great videos.

[Jeff Freeman]

When I use a super glue on Tip Overlays, I use Gorilla Glue GeL. Coat both surfaces and clamp lightly. JF

[Kirkll]

Thanks Kirk.  I take it that Bowyers CA has a longer working time than regular CA?  Great videos.

Not really…. But I don’t mess around long getting it clamped up either. I just use the thick viscosity Starbond for all my needs now. I use the thin viscosity for cracks and wood checks and thick stuff for overlays.  I buy it in large quantities and use it for other things too. Good stuff!

https://www.amazon.com/gp/product/B00C32ML9Q/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1