Re: [ULF-1] Sanding before gluing

From: Member 121
Date: 2018-06-14 19:07 UTC-07:00
Message: #0631
I buit lots without any glue .

On Thu, Jun 14, 2018, 6:56 PM Member 1 <[email]> wrote:

> Good points, Peter.
>
> When I began building airplanes decades ago the EAA had a great book
> about the different adhesives available. They were still talking about
> resorcinol and casein back then, but through the book and other research
> it sounded like they were not being used much any more. You guys are
> welcome to revisit that discussion, but I think it's a dead horse that's
> already been beaten to death in numerous other forums. A little web
> searching will probably turn up all you want to know about the topic and
> more. I'm happy with modern structural epoxies and learning how to best
> use them, so forgive me for being incurious about bygone methods.
>
> Except in the world of violins, where hide glue remains relevant because
> it is easily reversible and more sonically transparent than other glues!
> We do use epoxy for certain repairs that are difficult to close and we
> don't see anyone needing to open it back up in the future.
>
> To be nit-picky, I would disagree that a micro-balloon slurry is not
> structural. I agree that its tensile strength is low, but its
> compressive strength is significant for its weight. Hollow spheres don't
> crush easily, especially when they're being held in that shape by a
> rigid resin matrix. So any use I would have for it structurally will be
> designed to exploit its compressive strength (such as keeping a flat
> part from flexing out-of-flat), and no I would not count on it for any
> tensile loadings. I agree that a flox slurry will have better tensile
> strength, but if we're talking strength/weight ratio and loading in
> compression my money would be on the micro-balloons.
>
> Good discussion guys.
>
> Doug
>
>
>
> On [phone]:16 AM, Member 112 wrote:
> > Surely the preparation of the surfaces to be glued depends on the glue
> > to be used.  I am a wooden boat builder and my 15ft dinghies have no
> > fasteners - all glued joints.   I use epoxy for all glued joints and I
> > sand all joints before gluing and make sure that epoxy has saturated
> > the end grain or surfaces before making the joint.  Now, if I was
> > using hide glue (let me know if i'm wrong Doug) I would have superbly
> > made joints with an extremely thin, almost invisible, glue line.  Hide
> > glue does not fill gaps and there are many reason why hide glue is
> > used for violins, etc. and not epoxy!
> > Just my 2 cents - or 2 pennies!
> > Peter
>
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