Wayne,
Lots of guys set up a low budget rig whereby they direct the flame from the torch into
and through a piece of 2 pipe 8 - 12 long. Mostly this is used as a bending iron
to aid in bending wood for instrument ribs. With a little prior planning, it keeps
the flame away from anything that might catch fire and still provides some serious
heat. I've never used one, but I suspect it might provide sufficient heat for
gluing/ungluing purposes without the fright of turning a torch on an instrument.
Steve
Wayne Cripps [EMAIL PROTECTED] wrote:
Hi -
so there are questions about using jello as glue... well here is
my experience based on gluing the bridge back on a cheap
ukulele and gluing the peg box back on my lute..
1) using hide glue is tricky, try it on scrap wood until you get the feel
for it.
2) this discussion really belongs on the lute-builders list where all the
professionals are. I have used hide glue twice, they all use it every day.
3) using hide glue is tricky, try it on scrap wood until you get the feel
for it. especially using jello as hide glue!
4) read these web pages and understand them before you start..
http://www.frets.com/FRETSPages/Luthier/Technique/Glue/UseHideGlue/usehideglue1.html
http://www.frets.com/FRETSPages/Luthier/Data/Materials/hideglue.html
http://www.frets.com/FRETSPages/Luthier/TipsTricks/KitchenGlue/kitchenglue.html
be sure to follow all the links and references and read them too! The third
link is specifically about using Knox unflavored gelatin.
5) using hide glue is tricky, try it on scrap wood until you get the feel
for it.
6) this addresses some earlier questions... Hide glue sticks in two ways.
to prepare it you mix it with water *and* heat it till it becomes a
liquid. When you apply it it cools and becomes jello. This forms
a bond which is strong enough to hold the parts together without much
clamping, but not strong enough for a working joint. Then over the next
day or two the water evaporates or is absorbed into the wood and
the joint becomes strong. You will find that when a hide glue
joint is set up that heat won't loosen it, until you get close
to the charring point of wood, but gentle heat with moisture will
loosen the joint up very quickly. Because the hot glue sets by
cooling you will need to warm up the pieces that you are going to join
(over a propane torch flame - be sure to practice on scrap wood!!)
When the pieces cool to something like 90 f they bond enough to hold
in place while the joint dries. While the glue is moist you can reheat
the joint and try again. (You can re-stick old joints by getting them
wet, to activate the glue, then heating the joint and applying pressure.)
Hide glue is rated by gram strength, glue is mixed with a certain weight
of water, and allowed to cool, and tested by sticking something into it
to see how many grams of pressure are necessary. The higher gram
strength is therefore a thicker glue. Unflavored gelatin has a high
gram strength which means that as glue it is thick, and sets quickly,
while your more typical instrument maker's glue has a lower gram
strength which means that it is thinner and takes more time to set up,
which gives you more working time.
7) I use Knox unflavored gelatin which comes in packages of about 7 grams
(a quarter of an ounce). First try I first mixed it with 14 grams water, which
was a good consistency to apply but was too thin to have much tack,
so I tried 7 grams glue to 7 grams water. This was very thick,
and I had to work really quickly before the glue set up. Really
quickly means seconds, not a minute! I heated it to 140 f in the microwave,
by putting the glue and water in a custard cup, which was in a
small bowl filled with water, to even out the heat. I think it took a
minute in the microwave to get to 140 f. I had previously removed
the Titebold glue from the uke bridge by moistening it with
warm water and scraping, a long and tedious process. I heated the bridge
and uke top with my propane torch. Then I brushed some glue on
the bridge, put it on the top, and held it for a minute to let it cool.
There you go.
I used real hide glue for the lute neck, as I felt that I needed
something that would not set quite so fast!
8) using hide glue is tricky, try it on scrap wood until you get the feel
for it.
9) there is nothing quite like turning a propane torch on your
beloved lute!
Wayne
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