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Fabrication Issues


#1

I have two questions that I hope are not too burdensome to answer.
Question #1 is, are channels ordered from suppliers? Can they be
fabricated (and would it be worth the effort) out of sizing stock?
All sizing stock I’ve seen is too shallow to accommodate many stones,
especially colored I recently acquired the Allset
channel/prong cutting set, and in the instructional video, a jeweler
is cutting seats on what appears to be either a cast or fabricated
length of channel that I presume could be added to a mounting. I’ve
been unsuccessful in finding this type of pre-fabricated channel. For
all I know, it could have been just a prop to demonstrate the tool. I
always thought channels were cut into thick shanks, drilled and seats
cut for the stones.

Question #2 is, how do you decide what tubing size to choose if you
wanted to cut a seat and tube set a say, 2.5mm stone? Tubing in
catalogues list OD/ID dimensions. Would tubing with a 3 mm OD and a
2.12 ID be appropriate? How much wall thickness needs to be left in
order to securely set the stone? Thanks for your help!

Cathy


#2

Hello, Cathy

I thought for sure I would find premade channel settings in my
Stuller catalogue, but I didn’t find any (I may have been looking in
the wrong place). Generally, my experience has been that channel
settings are carved into a wax, and then cast.

If you want to fabricate one, don’t use less than 18 g sheet.
Measure the diameter of your stone, then make a channel a little bit
(about.5mm) narrower. If you’re channel setting large stones, use
thicker gauge sheet. When you make the channel, score two lines in
the sheet the exact width of the stones you’re setting. Then use
either a cut-off disc or a saw to start a groove. Use a file to
finish the groove (you’ll know you’ve filed enough to bend the metal
when an indented line appears on the opposite side of the sheet).
Then bend up the metal (use the edge of your bench), like you’re
making a box, and use hard solder to seal the bends.

In my experience, you could make more work for yourself grooving a
channel in sizing wiRe: The channel could end up being uneven, the
channel bottom could end up lumpy, plus it’s more work to polish out
the channel when you could just use sheet and have smooth polished
sides to begin with. If it works for you, it’s a good idea. It
wouldn’t work for me.

If you have any questions please holler at me.

Susannah


#3

some catalogues have great such as Hoover and Strong. You
can look up their tube bezel settings and they give you the Stone MM
Carat size and the MM OD and height. YOu can use this for a reference
for ordering tubing. A 2.5mm stone would use an OD of 3.02 mm.

Hope this helps.
Mary


#4
I always thought channels were cut into thick shanks, drilled and
seats cut for the stones. 

That’s more or less the way I make them.

How much wall thickness needs to be left in order to securely set
the stone? 

As a general rule of thumb, I allow 0.4mm minimum each side of the
stone. So for a 2.5mm stone I would make the chenier/tube 3.3mm
minimum outside diameter, and a 0.8mm wall thickness.

Cheers,
Dale


#5

Q#1

My preference is to use a manufactured channel when appropriate. Just
because its quicker which means less expensive.

You can fabricate your own channels but it can get tricky sometimes.
You need the following to be right on…width of opening, height and
thickness of rail, spacing of holes. On a curved surface such as you
might have on a ring, the centerlines of holes must be spaced a
little less than the diameter of the stones. How much less is
influenced by how close to the bottom surface the girdles come. The
closer to the surface, the closer to the diameter of stones. The
radius of the ring comes in to play also.

If you’re setting color in the channel things get a bit more
complicated. Very often you will have pavilions that are bigger than
a typical hart bur is designed for, so you have to go in with an
additional burr to accommodate. You might try reaming out the hole
with a bud burr til you get a nice, steady seat.

Hoover & Strong and others have flat and square wire in many sizes
that you can carve as needed. You can also solder the rails onto a
base. The advantage here is uniformity. The down side is solder
seams.

Get into curved or tapered channels and wax might be a better
alternative, depending.

Q#2

I’d like to see.010" to .015" wall thickness on something that size,
so your example seems in the right ballpark. You need less of a seat
for diamonds than for color. I’d start slightly oversize from there
to allow for polishing and off-center drilling (which can happen at
that size). Tubing can be stretched on a bezel mandrel.


#6

Hello, Cathy… I read a reply to this and had to go to the original
to get it clear - always a good idea. First, the easy one, which
another reply answers, also. Your measurement of 2.12 is about right
for a 2.5mm stone (see the other reply, too, though). But a more
general rule of thumb for all settings, bezel, prong, channel, is
that the stone should just NOT fit into the space. The stone should
just hang by the edges of the girdle on top of the setting. In your
mind cut a bearing into the setting, and the outer diameter of that
bearing cut and the stone girdle should resemble each other. I say it
this way because it’s more of a general way for any stone. The same
idea applies to a 15 x 19 pear shape and a 2.5mm round. This is much
more useful, because real diamond setters rarely encounter calibrated
stones, or calibrated tubing, for that matter. If you want to
practice
channel setting, there are many channel set pendants, or eternity
rings. While there do exist “premade channels”, there aren’t many and
I haven’t seen one in a while. The reason being as you say that they
are almost always built into the piece, like down a shank. If you
soldered a strip of channel onto a piece, it will look just like a
channel soldered on, and they don’t bend well at all. It’s a chore to
make channels, but it’s pretty easy, really. For melee size, I
usually
just cut them - I start with a round bur of 1/2 - 2/3 the stone
diameter to sink it, and then finish it off. This is what equalling
files are made for, that kind of work. For larger stones there are as
many ways of making a “U” profile as there are people - cut a base
piece to width and solder two strips on either side - I like to bend
a wire into a long “U”, solder it onto a base, and then cut off the
"U" part - instant channel, with some tweaking…

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