Author Topic: Bad glue joint, lets see what we can learn from it.  (Read 3171 times)

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Offline dylanholderman

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Bad glue joint, lets see what we can learn from it.
« on: February 11, 2017, 11:26:54 pm »
Ok so my first foray into a lam bow didn't go well. Bad gaps in the fades probably from not enough pressure.
But sense that's the case I figured I'd bend it and see what happens.
Any thoughts or advice before I do?




Offline justsomedude

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #1 on: February 12, 2017, 12:06:04 am »
Yep...Armguard and Safety Glasses!

Offline bubby

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #2 on: February 12, 2017, 12:08:49 am »
What glue did you use?
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

mikekeswick

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #3 on: February 12, 2017, 03:42:04 am »
When you make a powerlam you need to feather the ends very carefully to nothing. The very end should be see through and it will go 'wavy'. I inch from the tip should be no more than 1/16th thick. You had too steep a transition. If you had clamped hard enough to close the gap then you likely would have ended up with a weakness there anyway through excessive pressure.
why not bend it to destruction! You will learn something!

Offline Del the cat

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #4 on: February 12, 2017, 04:43:44 am »
Haste is the big enemy with preparation and glue up. There is a lot to be said for doing a dry run first, assembling with no glue, it will show up problem areas. Regarding pressure, I use rubber strapping, at least two layers. IMO, if you can see any wood between your clamps or strapping, you don't have enough.
Don't worry, we all screw up, I've had to rasp off a bamboo backing before now and re-do it. :-[ >:( :laugh:
Del
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Offline Eric Krewson

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #5 on: February 12, 2017, 08:46:00 am »
I have had similar glue joints on BB osage bows, I filled the void with superglue (no clamps) and forgot about it, no failures to date.

Offline Pat B

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #6 on: February 12, 2017, 09:17:27 am »
I've done the same as Eric.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Dances with squirrels

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #7 on: February 12, 2017, 12:57:01 pm »
Go without on the next one. You don't need a power lam. It's extra work, complication, and risk.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline dylanholderman

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #8 on: February 12, 2017, 02:43:45 pm »
Thanks for the advice guys
I'll fill the gaps with CA glue and see what happens when I go to bend it.
The glue this time was TBII.
I think the next bow I try to glue up will just be a straight longbow maybe will a little reflex

mikekeswick

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #9 on: February 13, 2017, 03:47:17 am »
Powerlams are a really useful technique. In my eyes it is better to keep at it until you get it right rather than do it once then move onto something else. Another 15 minutes sanding and prep and this would have been fine.

Offline Springbuck

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #10 on: February 15, 2017, 02:57:42 pm »
I've done the same as Eric, but in my case I was totally sorry later.......

Now, this worked for me a couple of times, but I'm NOT saying I recommend it, exactly.

If you just put more glue in and clamp down harder, the dried glue inside maintains the gaps and stops you.  But, the glue is strong, it just doesn't fill the gaps well.

So, once I really wanted to save a hickory backed black locust recurve I made.  The hickory had cupped when wet, and my clamps didn't span the whole backing width, creating gaps a lot like this.  The limbs were fine once I trapped them, but the fades were iffy, and  some backing on the handle was lifted in bad spots.

   So took a propane torch and an old butter knife and an old utility knife blade held in some vise grips, heated them red hot and burned and melted away any  glue in the gaps, but not doing anything. Then I tried to guess the general shape of the little flat cavities I had made.  I clamped the area so it couldn't spread.

Then, I took some hickory veneer I had, snipped it into bits and slivers, dipped them each in TB III as I went, and tapped them in, like little shims using a tiny stick for a mallet. I filled the hole with glue ahead of time, too.  The shims drove almost all of the glue, and I basically smashed as much wood as I could pack in there, gently.

It worked, the bow is still shooting (gave it to a work buddy).  You could barely tell once sanded. 

I don't think it would work in every case.

Offline Del the cat

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #11 on: February 15, 2017, 06:19:51 pm »
Gaps are no good >:(.
Take it down and re-do it properly it's simple as that.
OK you may get away with the occasional filling the gap with CA fix... if you really have to for some reason, like you need a bow at short notice.
I think the main thrust of this forum is to promote good skill and craftsmanship.
Yes there is room for rough and ready experimentation at times, but as I see it we are about good sound quality of work and sharing our skills and experience.
After all we have bow of the month, not botch of the month!  >:D
Del
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Offline jeffp51

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #12 on: February 15, 2017, 10:17:40 pm »
I am with Del.  Perfect is good enough.  Anything less is not satifactory when you are gluing surfaces that will take strain.

mikekeswick

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #13 on: February 16, 2017, 03:54:06 am »
I am with Del.  Perfect is good enough.  Anything less is not satifactory when you are gluing surfaces that will take strain.

Yes we aren't making a piece of furniture! Laminated bow gluelines have to take quite a bit of 'workin'!
Perfect is good enough :)    Now there is a saying worth putting on the wall of my workshop :)

Offline Springbuck

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Re: Bad glue joint, lets see what we can learn from it.
« Reply #14 on: February 16, 2017, 07:38:42 pm »
We say "Perfect is good enough." in Radiation Therapy, when aligning and positioning patients for treatment.