Bow Broke..:-( Help me understand what went wrong

[arachnid]

Originally posted by Robertfishes:
Arachnid, what I do is use my plastic squeege to push "smooth on" into the lamination, add smooth on onto the squeegee and go over the lams again, wait a minute or two and repeat.. The last pass I use no pressure and build a thin layer of epoxy over the lams. I am a hobby builder and I don't care if I use a couple more ounces of epoxy doing this. **Edit* And use a good light so you can see any dry spots..

I don't use a plastic squeegee, I just use a thin piece of wood (usually a lamination cut off).
Hiw do you "push epoxy into the lamination"? Can you explain?

[Robertfishes]

As I am first applying the epoxy I am pushing down on the flexible plastic squeegee. The squeegee is not at a 90 degree angle to the lamination it's at a 45 to 60 degree angle.. So the squeegee is loaded like a spring, pushing down against the lamination and hopfully "forcing" the epoxy into any small natural voids in the laminations.

[arachnid]

Lots of good and important lessons learnd. I consider it a positive experience.

Thanks a lot guys. You're the best.
If there's anything else I need to know- please share with me.

[HMlongbow]

yep the glue lines is where it failed and make a sister to original form and use a air hose.  that is where the issues went and to much stress and I would like to see a more favorable taper on top side of handle.  seems as though to much stress at that point

[Wolftrail]

Originally posted by Robertfishes:
It's best to apply epoxy to both surfaces because..some of it soaks into and fills the air spaces in the wood grain. This makes for a better bond between the 2 surfaces. I use a auto body plastic squeegee and it pushes smooth on into the glue surfaces. I make a couple of passes, wait a minute then apply more epoxy to the surfaces.

Excellent point, had a few failures because I did not apply glue to both surfaces.

[arachnid]

How about my lam grinding setup?
I only have 80 grit sleeves, is that ok? Do  need to rough the surface before glue up?
If so, how?

[Dazzad]

Hi Arachnid, btw this is my first post on Tradgang - nice to stop lurking and start getting amongst it!!
I'm still in the process of getting my D/R form made, so you are many steps ahead of me!!
I've made a few laminated hill-style longbows though and felt compelled to add my input to the great and constructive comments you have already received.
The bow in the very first photo looks fantastic! Very disappointed for you with it's sudden (and surely shocking!) demise.
The comments you have already received regarding the steepish taper of the fades and the fact there are one or two glue lines at said fades pinpoint a couple of refinements you'll be able to implement in your next bow, but I kind of breathed a sigh of relief on your behalf when you revealed that you only applied your epoxy to one of every two surfaces. I think that's probably about 90% of your problem mate - if the only thing you do differently next time is glue wet surface to wet surface (with lots of squeezout), you'll be firmly on the path to success!
There is one closeup photo you supplied of the riser area, and it looked to me that a few of your glue lines were just lacking glue.....
Fwiw I would have thought an 80 grit finish will supply ample tooth for good joins, provided that they are clean, tight fitting, and all of each surface wet with epoxy.
get back on the horse mate, show us how u go and best of luck:)

[arachnid]

Originally posted by Dazzad:
Hi Arachnid, btw this is my first post on Tradgang - nice to stop lurking and start getting amongst it!!
I'm still in the process of getting my D/R form made, so you are many steps ahead of me!!
I've made a few laminated hill-style longbows though and felt compelled to add my input to the great and constructive comments you have already received.
The bow in the very first photo looks fantastic! Very disappointed for you with it's sudden (and surely shocking!) demise.
The comments you have already received regarding the steepish taper of the fades and the fact there are one or two glue lines at said fades pinpoint a couple of refinements you'll be able to implement in your next bow, but I kind of breathed a sigh of relief on your behalf when you revealed that you only applied your epoxy to one of every two surfaces. I think that's probably about 90% of your problem mate - if the only thing you do differently next time is glue wet surface to wet surface (with lots of squeezout), you'll be firmly on the path to success!
There is one closeup photo you supplied of the riser area, and it looked to me that a few of your glue lines were just lacking glue.....
Fwiw I would have thought an 80 grit finish will supply ample tooth for good joins, provided that they are clean, tight fitting, and all of each surface wet with epoxy.
get back on the horse mate, show us how u go and best of luck:)    

Thanks for the kind works dude. I already started grinding the lams for my next one.

I`ve been making wooden bows for 5-6 years now so I know what it`s like to brake a bow. But, lessons were learned and off we go again...

[Robertfishes]

I buy my tapers from Tradgang Sponsors. I think they use 40 grit on most tapers. I have seen some that might have been sanded with 50 grit? When I shape riser fades I use a 50 grit zirconia belt. I believe the Smooth On web page says 120 grit. I think 120 is fine for 0.025 veneers where the Smooth on penetrates into the wood maybe completely? but I want my thicker parts like tapers and risers to have a glue surface sanded with something rougher like 50 grit.. You asked if 80 grit is OK, I think it is but 50 grit would be a better choice for me.