Author Topic: Gluing pressure  (Read 4074 times)

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Offline DC

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Re: Gluing pressure
« Reply #15 on: January 12, 2017, 01:32:39 pm »
OS has a bad habit of splitting through the handle. I have cut a "V" along the split and inlaid a piece but it's a lot of work to get a good fit. I have also filled the crack with bondo or sawdust and epoxy. The couple of times I have cut the handle off and tried to glue on a solid handle it has tried to pop off. I always use West105/205 epoxy. I'll try again. This time I'll score it lightly and use less pressure.

As an addition, when the handle tried to pop off I flooded the crack with CA and the joint held after that. Does that sound like it may have been starved the first time?

Offline willie

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Re: Gluing pressure
« Reply #16 on: January 12, 2017, 02:00:04 pm »
DC
 
do you use a filler or thickener with the 105/205? I have used cabosil in the past, but avoid fillers on critical or difficult to glue joints.

I have had good luck with using time and temperatures modifications to the resin without fillers.

Offline DC

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Re: Gluing pressure
« Reply #17 on: January 12, 2017, 02:45:20 pm »
I usually use a little Cabosil and I have a small oven(box with a lightbulb) that goes to about 120 degrees. I can't say for sure if I used both of these on the joints that popped. I've been doing a little reading about clamping pressure and it appears that I am using way too much, especially with epoxy, so I will modify my methods. I will have to prep a stave and pop it in my hot box for a few weeks and see what happens.

Offline BowEd

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Re: Gluing pressure
« Reply #18 on: January 12, 2017, 03:46:34 pm »
DC....If done properly smooth-on does go into the pores.The wood needs to be warm along with the glue and a 36 grit surface is your best type of surface to use.C clamp pressure is a by feel thing and inner tubes as tight as I can get them.I personally have not had a failure from doing it this way on quite a few different bows.If done properly with smooth-on the wood will pull apart before the glue line will.
A person can calibrate a C clamps pressure if you think hard enough.Inner tubes too.By just using a poundage tester,but I really don't think it's necessary.I think you are over thinking this problem.I never turn a C clamp down as hard as I can.After contact just a couple more turns is all without much effort.
Wood glue like elmers and tite bond do not shrink.Neither does epoxy.Only hide glue shrinks.Hide glue can pull pane glass apart or etch it so to speak.That's as smooth a surface as your gonna get.
I'm speaking from using all glues I've mentioned extensively.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline BowEd

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Re: Gluing pressure
« Reply #19 on: January 12, 2017, 04:04:35 pm »
Your handle belly I would fill in with strips or slivers of wood or maybe even combed flax with smooth-on.Extend fades a little if possible.I then would wrap handle with sinew or nylon and smooth-on.Then sew a wet piece of thick rawhide around the handle too.I would feel pretty confident of that holding together.Bomb proof!!!
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline DC

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Re: Gluing pressure
« Reply #20 on: January 12, 2017, 04:25:13 pm »
It's strictly an appearance thing. I am quite confident using those cracked handles. I have filled them with Bondo which has almost zero strength and had no problems. I just don't want them to look like a cobbled-up piece of crap.

PS the piece of crap I was referring to was the bondo not your idea Ed. Sorry if that came across wrong.
« Last Edit: January 12, 2017, 04:30:57 pm by DC »

Offline bubby

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Re: Gluing pressure
« Reply #21 on: January 12, 2017, 06:27:31 pm »
I know you are using a stave but wanted to show this handle was glued and clamped with just spring clamps
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline DC

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Re: Gluing pressure
« Reply #22 on: January 12, 2017, 08:58:03 pm »
Nice joint Bub

Offline Springbuck

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Re: Gluing pressure
« Reply #23 on: January 20, 2017, 05:44:49 pm »
DC, V cuts were such a pain in the rear, I just went to a squared up kerf by using the table saw. easy to slip a cut slat in to.  Works best if you have a way to clamp it the same for each pass, but maybe 4 hacksaw blades bolted together on the ends would clean up the cut enough?

Anyway, other than that it's all been said EXCEPT..... I have had a lot of trouble with some woods cupping a lot more than others when using water based glues, even TB III.  Thinner belly slats do it more, like a 3/8" thick belly lam would cup more than a 1/2" one.   Goncalo alves was the worst for me, but other woods will do it, too. 

 I would check my fit, and be really happy. Then, when I wet the surfaces with sizing or applied glue, the whole slat would cup, turning the edges down and the glued side convex, bulging uip lengthwise in the middle.  It's amazing how strongly this would defy the clamps, especially rubberbands, creating a tiny gap all along the edges between the backing and the core.  Then I'd have to mess with adding more glue to the edges and reclamping here and there, or trapping the limbs to see if it would go away.

I started wetting both sides and waiting a few minutes to see what the wood was gonna do, then gluing when the surfaces were mostly dry.
« Last Edit: January 21, 2017, 11:48:45 am by Springbuck »

Offline bubby

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Re: Gluing pressure
« Reply #24 on: January 20, 2017, 06:38:18 pm »
Thanks DC
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹