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