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

[Mad Max]

Originally posted by Crooked Stic:
What kind of core wood? It looks curly to me. If you use curly grain for much more than veneers you are asking for trouble.

yep

Hey arachnid...  I found that in life it is usually 3 steps forward 2 steps backward, and that is if you are living a progressive and positive existence...  Chit is gonna happen, especially in this craft...  Learn from it, Cover all your bases and Move on... I can't tell you how many experiments I have done and failed to hit my mark...
 
  Put that bow up as a reminder of lessons learned  
  and start making a new bow...
  I would keep the accents out of the fades...
  Make them fades lean...
  Put ample glue on...
  Don't clamp too tight... (under 40 psi)
  The more lams the better... Anything over 35#    
  should be more than 2 core lams...
  Watch the woods you use...
  Keep your fingers crossed...        

  These are my opinions that might lessen the chances of this happening again...

  Best of Luck, Bro...

[arachnid]

Originally posted by Shredd:

  Make them fades lean...
 
...

Please explain

[kennym]

Originally posted by arachnid:
 

Originally posted by Shredd:

  Make them fades lean...
 
...

Please explain [/b]

Think Rich meant thin them out nicely...

[arachnid]

When using more then 2 core lams, say 1 tapered and 2 thin paralles, does is matter in which oeder you place them and where you place them (on the back/belly side of the riser)?

[kennym]

Not in my opinion, once glued up it is a composite structure, all bends the same....

[Holm-Made]

Did you butter up all glue surfaces?

Originally posted by kennym:
Shredd may have hit on something with the accents into the fades, look at how the black bends right at the joint on belly.

But it may be the fades are a bit blunt too. 1/16" at 1", and 1/8" plus a little at 2 (.140" and yes I measure with dial calipers when grinding them) is what I always try to get.

Leannnn...  What Kenny said...  That's how I do mine also...  1/16" thick at the 1" mark and just over 1/8" at the 2" mark...  You want a nice smooth transition that distributes the load...

[arachnid]

Originally posted by Holm-Made:
Did you butter up all glue surfaces?

Which means??   :confused:  

Shredd, does these measurements (of the fade transition) apply also when using a powerlam?

[Holm-Made]

Did you put smooth on epoxy on all of the surfaces to be mated?

If you are epoxying two laminations together, you need to spread the epoxy on both laminations completely before putting them together.

[arachnid]

Originally posted by Holm-Made:
Did you put smooth on epoxy on all of the surfaces to be mated?

If you are epoxying two laminations together, you need to spread the epoxy on both laminations completely before putting them together.

I actually did not... I spread glue only on one side.
Why spread both? It'll just cause a big squeeze out, no?

[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.

[arachnid]

How thick of a glue layer should I apply on each surface?

[Holm-Made]

A starved glue joint was the reason the bow failed.  You MUST apply epoxy to all surfaces to be mated or a high percentage of your bows will fail.  This is standard procedure for building bows.  
Good luck.  Chad

[Bow man]

Originally posted by Holm-Made:
A starved glue joint was the reason the bow failed.  You MUST apply epoxy to all surfaces to be mated or a high percentage of your bows will fail.  This is standard procedure for building bows.  
Good luck.  Chad

X2

[Crooked Stic]

The reason I know curly is not a good core wood it failed on me twice before I figured it out. You may get a few shots out of it and boom. It may have grain running length wise but the curly part of the grain goes from front to back of the lam and will take no pressure. When in veneer form between glass and a good straight grain wood you are fine. Be sure to do a dry run and check everything out on your next one. Keep those fades thin for a couple of inches on each end. They bend a little bit to.

[Bvas]

Originally posted by arachnid:
How thick of a glue layer should I apply on each surface?

This is hard to explain......I also use the plastic squeegee.  I use just enough pressure on the squeegee to leave a nice thin coating on the lams.  A good light will help you check to make sure that the lams have a nice slick wet look to the ENTIRE surface.  Look closely for any dry spots.  
And yes, you will have squeeze out.  Better to waste a little glue then waste an entire bow(and a bunch of time).

[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..

[arachnid]

Originally posted by Holm-Made:
A starved glue joint was the reason the bow failed.  You MUST apply epoxy to all surfaces to be mated or a high percentage of your bows will fail.  This is standard procedure for building bows.  
Good luck.  Chad

That makes a lot of sense. After it broke, the inner side of the glass and wood feeled smooth, as if there was no glue remains in them.

[arachnid]

Originally posted by Holm-Made:
A starved glue joint was the reason the bow failed.  You MUST apply epoxy to all surfaces to be mated or a high percentage of your bows will fail.  This is standard procedure for building bows.  
Good luck.  Chad

That makes a lot of sense. After it broke, the inner side of the glass and wood feeled smooth, as if there was no glue remains in them.