On Tue, 30 Dec 2008 21:44:14 -0800 (PST), "
wrote:

On Dec 30, 2:11*am, Stealth Pilot
wrote:

this was just too good to snip out so I didnt :-)



you mention glue.
how do you make that?
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How you make it depends of what you're trying to glue together.

A good general purpose glue is made from raw hides. This can take a
pretty strong nose.

Go to one of the big Chain Stores that carries Pet supplies. Buy some
pigs ears or dried 'chewables' of rawhide.

Try cutting the rawhide or dried ears into smaller pieces. Depending
on how they were prepared, their size can be as large as 8x10 inches.
For making glue you want the size to be more on the order of 1/4 x
1/4" or in the form of strings. Soak the pieces in water until they
are fully saturated then begin adding heat. To maintain control of
the temperature you'll need to use a double boiler.

If you've never made hide glue, start by BUYING SOME, so you'll know
what it looks like. It is made from rawhide -- the residue of making
leather -- or from hooves and horns. Properly made, the stuff looks
like honey. In use, it may be thinned and heated.

Rawhide itself is rather handy stuff. When saturated with water it
can be stretched but will try to shrink back to its original size
unless restrained. You can make molds of things you wish to protect,
such as some of your precision tools. Soaking the dried rawhide in a
light oil will prevent it from absorbing water and losing it's shape.

For homebuilders the most useful glue is Casein. This is made from
the protein in MILK. Run your milk through a cream separator more
than once, or allow it to stand, giving the cream time to separate.
When making milkglue you want to be damn sure that you do NOT get any
cream in the mix. If you live in an area that does not provide real
milk, visit your local grocery store and see if they carry 'fat-free'
or 'skim' milk.

Starting with skim milk, add an acid such as vinegar to cause the milk
to 'turn'. Stir the milk to ensure the acid reaches all of the milk.
Allow it to stand for about half an hour then pour off the liquid (ie,
the whey) then whisk the curds into a uniform paste and neutralize
them using bicarbonate of soda dissolved in water. Heat this mix in a
double boiler to reduce it to the consistency of heavy cream. If you
are not familiar with this consistency go BUY some heavy cream... or
allow some real ice cream to melt. The basic test is to take it up a
teaspoon at a time and allow it to pour back into the container.
'Heavy Cream' is the point at which it pours back as a single stream
rather than as a series of drops.

The next step is to make sure you have neutralized the acid. The best
way to do this is with Litmus paper, purchased at the drug store or on-
line. If that is not available to you, you can do the test with a
STRONG mixture of bicarbonate of soda in warm water. Add this to
your mix ONE DROP AT A TIME whilst looking for it to generate any
bubbles. If the mix is still acidic you will have to add more
neutralizer, stirring it in good and repeating your tests. The
problem here is that you are trying to achieve a NEUTRAL mix, one that
is neither acidic nor base. The tests make it easy to DETECT acidity
but not the opposite, unless you are using Litmus papers, so you want
to very careful that you do not end up with a mix that contains too
much bicarbonate of Soda because the soda will precipitate out as
crystals within the glue line, reducing its strength.

If you glue is too thick you may dilute it with water; if too thin you
may heat it to drive off some of the water. When you have achieved
what you believe is your best mix, you must test it using the standard
FTC shear-strength test. That is,a coupon two inches wide by four
inches long, with the adhesive applied to a 2x2 area. The adhesive is
applied to both faces and clamped with approximately 70 pounds of
pressure, all this while maintaining a gluing temperature of about 70
degrees on the Fahrenheit scale. The test-coupon is sheared at the
glue-line by clamping the free end in a vise and striking the other
free end with a three pound hammer, using enough force to cause the
sample to fail at the glue line.

Examination of the failure should show that the WOOD failed over at
least 80% of the glued area.

Casein glue is stronger than most of the softwoods used in aircraft
fabrication. Unfortunately, casein glue is subject to biological
attack by bacteria and fungi. For that reason it is important to seal
any glue-line with varnish or paint as quickly as practical, and to
include inspection of that sealing surface, for any aircraft in
service. In a similar vein it is important that you do not allow any
glue to become contaminated before it can be used.

-Bob

-PS -- One of the more important uses of rawhide is 'corners.' (!)
That is, on tool kits and small pieces of luggage, or the cases for
such things as VOM's, binoculars and so forth. It's a fairly simply
chore to make a corner of solid aluminum, or of hardwood well sealed
with varnish, over which you may stretch a piece of saturated rawhide,
tacked or clamped to the back of the form until the rawhide is fully
hardened. It is then trimmed to the required shape and attached using
stitching, glue or rivets.

And of course, we use rawhide for mallets :-) Often times we need a
mallet having a particular shape and the only way to get one is to
sacrifice a new mallet, sawing the rawhide to the desired corner &
curve. But if we have a supply of rawhide (strip is handiest for
this) we can literally 'roll our own,' producing a tool that is far
superior to making the head our of lignum vitae or whatever. - rsh

talking about hammers reminds me. I needed to tap the vise into
alignment on the mill table. I was chopping up some pretzeled up
pranged aluminium propellers to machine little lengths of them for
flying instructors to trace around when they want to draw an aerofoil
on a white board.
I'm a great fan of 4 ounce ball pein hammers so I reached for my
favourite 4oz.
I was in mid swing with my first tap when I thought ...hang on,
that'll peen the side of the thing, hmmm cant do that.
what I needed was a soft face tapping hammer but I didnt have one.
I went down to the local home depot which we call bunnings.
bloody hell they are expensive!
buying one was outa the question but I still needed one!
so I took a 1 inch diameter bar of mild steel and cut 45mm off the end
in the band saw. I chucked it in the lathe I use to machine up
aircraft replacement bits, faced off each end and bored a 10mm dia
hole in each end.
I'm a great fan of wooden hammer handles so I milled a flat on
opposite faces of the head and drilled through to make a hammer handle
hole. you know the double taper socket style which turned out to be
easy to mill out then file to final shape.

I must digress to tell you of the handles. bunnings no longer stock
4oz ball pein hammers, in fact almost nobody seems to, because they
never wear out the one you have is with you in yeoman service for
life. the stores seem to think that no one needs one at all so they've
dropped them entirely ...the dumb *******s.
anyway in the middle of the gardening section of bunnings I came
across a box with an entire set of 4oz replacement ball pein hammer
handles.
I know that they were dumped there in the small picks and mattocks
section because no one in bunnings recognised what they were :-)
so I have a bunch of these el cheapo premium quality australian made
handles. I must go back and buy the rest, they'll think they're a hot
item and buy in more :-)
anyway after I sprayed the head black using the rattle can I use on
the backs of my prop I fitted one of these premium quality handles to
my new hammer head. ...oh it's like a finger in a bum. (you remember
the innocent old WW2 definition before poofters became a part of the
landscape, you're as old as me so you orta )

I needed some nylon for the faces because I have no access to rawhide.
so I used the end of the bit I turn my tailwheel bushes from. it is
inch diameter graphite filled nylon. I machined one end flat and
leaving 15mm for the head turned a 10mm dia pin out the other end.
I turned up two of these and using the vice pressed them into each end
of the mild steel head.
the entire head is black with this beautifully fitted 4oz ball pein
handle.

what surprised me is that it turned out to have perfect balance.
it just feels absolutely right in the hand.
for something I brewed up in a few hours just to tap the vice straight
cause I couldnt waste 70 bucks on a bought one I'm bloody chuffed!

my model engineers club just roll their eyes when I talk aeroplanes
but I think that even they will appreciate its fine qualities so I'll
repeat this as a quick talk next meeting.

I hafta wonder though. you talk of such different things when you talk
airplane that I wonder whether they are even similar to my aeroplanes.
I dont have a back yard big enough to grow really tall trees so I buy
in 6" x 2" alaskan yellow cedar poolside decking planks. I cut these
down on my 40 year old cast iron saw bench. I glue the raw bits
together into aeroplane parts using epoxy resin, which is probably
just wuna them there new fangled things to a fella like you.
there is a coupla tricks to using it which I could tell you about if
you wanted.
the aerofoil I use is called a naca23102 which is kinda neat but it is
difficult in that you cant use the sida yer thong to draw it like you
can with the adidas9 aerofoil. but lay one out on a sheet of mdf,
thats secret tla speak for medium density fiberboard, and it is a
cinch to make a building frame.
you guys have invented the steam engine havent you?
well another use for steam is softening the thermo softening lignins
in the alaskan cedar so that you can prebend the wood for use on the
building frame. I do that a lot and I use a technique called
laminating to make lotsa curved bits. If you havent heard of
laminating I can tell you about it.

one thing you have all over me though is the conversion of these
little german engines. I cant get suitable ones at all.
so today I made the casting pattern for the sump of an ET Westbury
Sealion engine. its only small but it is the first step on the way to
building my own aircraft engines. I figure I'd practise on little ones
that were cheap to build before I venture into one for my aircraft.
I intend building a few different designs in 4 cylinder engines as a
leadup to my own aircraft engine.
dontcha think a scaled down continental O-200 engine would make the
darndest little ultralight engine. :-) I could even cheat and use some
of the bits from the little german ones to make construction faster.

just before I go and get anotha beer from the 'fridge. do you know
about that there genetic engineering stuff. well ova here in australia
we kin git little bottles of a stuff called success. you mix this
concentrate in water and spray it over the tomatoes. the little
genetically modified soil bugs in it give the bugs one hell of a dose
of stomach poisoning and they all die. actually you shouldnt use it.
you'd have nothing to cuss about and from all reports your neighbour
rather thinks you're a hunk because of it.

well that beer beckons. next time I must tell you about casting my own
wheel hubs.
your friend unda the verandah
stealth pilot