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'U' channelling


#1

Hi, Often, I have to make ‘U’ channeling in gold for inlay
work . Normally organic material, like warthog hair, giraffe
hair or elephant hair is inlayed. I normaly make the 'U’
channel 1mm x 1mm on the inside and the outside dimensions are
normaly,2.5mm wide x 2.2mm deep. For example, if you make a
wedding band , say , 3mm x 2mm , where the 2mm is the thickness
,and the 3mm is the width, then , if you put a 1mm channel into
the band, you will have wall thicknesses of 1mm on either side
and a ‘floor’ thickness of 1 millimeter

Straight channels are easy, 'cause, all you got to do is cut
with your saw (No 3 blades ) and then folow up with a 1mm barell
fraser or a flat needle file…

'S ’ shaped curves, however, are a mission. So are 'C 'shaped
curves. If you make them with a ball frazer then the curves are
not smooth . You can’t cut them with a straight frazer, 'cause
the sides get dinged. Ditto for using a saw blade.And my
engraving skills are not good enough to engrave a curved 'U’
channel neatly

So… I make’U’ channeling in the metal in the following manner,
First, I work out what wall thickness I want. Then I make round
tubing. in the standard manner, keeping the solder joint nice
and straight and on top. I then fit copper wire , that I have
drawn down to the required diameter, into the tubing. Okay, so
now I got say 3mm diameter tubing, with a wall thickness of .7mm
and a copper wire of 1.5mm inside the length of the tubing.

Then I draw the tubing down in my square draw plate to the
final dimensions that I want. Sometimes I draw it down square
and then roll it to an oblong shape. I’ll cut a slice off the
back end to see what the copper’s profile looks like. Once I am
happy with my dimensions, I then bend the tubing/wire into the
shape that I want, keeping the solder joint on the top. The
tubing acts like wire, 'cause it’s got the copper in it
supporting the walls and so it doesn’t kink… Then I file the top
of the square tubing off,and in so doing I also file the solder
joint of the tubing away , until I expose the copper. Then I
burn the copper out with Nitric acid,and I am left with a
seamless piece of ‘U’ channeling, that is absolutely smooth and
true on the inside. Nitric is a bit nasty, I think Ferric
Cloride would also work,although a lot slower (I haven’t tried
it ). I sometimes take a piece of finished channeling and melt
it into a wax model, and cast it in situ, say for channel set
stones. Maybe the thread of making grooves in wax could use this
technique? Sometimes I don’t draw it square, but draw it round,
and after filling, I have a ’ C ’ profile.

Cheers, Hans Meevis


#2

Hello Hans! I am familiar with the technique, but have never used
it. Your effort was wonderfully presented! Appreciate your
effort! I’m sure their are many others ecstatic with you post,
thank you! I have only used nitric for etching, and as an
ingredient for “bright dip” years past. Would you treat the
different karats of gold, ie. 14k, and 18k differently for the
copper removal process? Could you give your dilution rates and
state immersion times. Will be watching for your future posts.

	Thanks again!
									
	Tim