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Flush Stone Setting


#1

The ability to consistently create a flush setting has always
eluded me. I have found only brief explanations of the
procedure and none of my books on stone setting address it.
Where I seem to fail in the technique is in the final setting of
the stone where the metal is burnished around the stone. In one
of my workshop notes I have written that the tip of the
burnishing tool must have a critical angle but does not describe
the angle or the proper method to apply the burnisher to the
metal. Can anyone explain this procedure or know of a good book
that describes it.

George Hebner
ghebner@artsights.com
http://www.artsights.com/ghebner


#2

George Hello!

I’ll see if I can explain my method for “flush” (also called,
rubbed in, and gypsy) mounting stones. You asked for a tool
description; here’s the whole enchilada. Compare (no you don’t
need to measure) the stone to a ball bur that is smaller than
the stone. If you use the comparison method, you’ll find it very
fast and accurate for creating a seat from your memory of the
differences between your chosen bur and the stone. Personally, I
rarely need the dimension of a stone, prefering to memorize the
compared difference between a bur and a stone. Use a 3 inch
brass guage for this (smooth the guage so it glides easily
(opens and closes) with one hand). Choose a ball bur 10 to 20%
smaller than the stone. Bur down just over (barely) half way
with the ball bur. Let’s assume you’ve a;ready drilled a hole
!/2 to 2/3’s the size of the stone. Now with your "comparison"
guage choose a 45o hart bur that is slightly smaller than the
stone. A good reference would be 5 to 10% smaller than your
stone. In the case of a 4mm stone use a 3.7 mm bur to create a
preliminary seat. Imagine the stone set with table level ,or
permissibly, slightly above the surrounding metal. Memorize the
table to girdle dimension and use your hart bur to duplicate
this intended dimension for your seat depth. Start the bur in
side “A” at 75o to 80o degrees and cut gently while rocking the
bur to 90o and completing the seat. Be careful not to create to
deep a bearing. Here’s where it gets tricky. The stone now, will
not go in the hole! Do not keep cutting deeper and deeper with
the hart bur! Choose a ball bur, a 3.7mm a good choice.
Carefully create a larger opening with the ball bur a little at
a time. Check your stone for fit often. Only try to fit the
stone the same way you cut the seat; side “A” first. If it still
does not go in use the hart bur to slightly increase the
diameter of the seat. You could take a 4mm hart bur and sharpen
with a thin separating disc, therefore decreasing the diameter
to say 3.8 to 3.9mm. Position the bur in your fingers to allow
cutting of the upper row of teeth. Follow the original angle and
tooth pattern as best you can. The bur will likely not last as
long as a machine cut pattern; but they don’t make a 3.8 or
3.9mm hart bur! Start the bur in side “A” and rock to side “B"
gently and smoothly; easy on the pedal. While in the seat,ever
so carefully increase the seat size, being certain your cutting
level by rotating the piece. If the stone still will not go in,
your very close! Use the ball bur again. Oversize and check
stone for fit. Yes! The stone with a gentle thumbnail push,
snapped into place! (here we go George!) You now need a
"polished point” in a handle. Millgrain handles work well. Your
polished point is made from a worn out vanadium bur. The point
should be tapered to approximately one mm give or take. For
small stones (1mm to 2mm a smaller point is desired. For say a
6mm stone about a 1.25mm is prefered. Shape the tool to the
intended diameter by grinding, emery board etc. Final shaping is
accomplished by fitting in your handpiece and drawing it across
your emery paper, rubber wheel, etc. Final finish at your
polishing motor with tripoli (black works well on steel if you
have it) The point should be slightly domed, not rounded like
the tip of a pool cue. More like the chrome clicker on the top
of a pen. The edge should be more rolled than that however. Now
at near parellel to metal angle (even with table,plus 10
degrees) use even pressure, gently with the first go round. You
are burnishing the metal towards the stone, not down yet. Make
several passes until you can appreciably see you’ve effectively
moved the metal towards the stone. Now change your angle of
addressing the metal to approximately 65o to 70o degrees and
again burnish the metal. Start with light pressure,and evenly
burnish the metal back, this will smooth and tighten the stone.
You must be careful not to score the crown facets of your stone!
Even diamonds fall victim to this metthod of setting if due
caution is not constant! Invariably, you will swipe at a crown
facet occasionally, and scratch your polished point. Chuck it
up in your handpiece and renew it on a rubber wheel then hit it
on the tripoli buff. Now your ready to set another stone! There
are other methods to be sure. I used to use a wax pen and build
a little mountain range around each hole; what a mess! Hope
you’l ltry it, and it works for you!

	Tim

#3

Hi Tim

Thanks for the great comments on flush stone setting. My notes
for creating the stone seat is pretty close to yours with the
exception that my notes say to create a bearing cut completely
around the seat with a small 1 mm h art bur. My burnishing tool
was pointed and I have domed it as you suggested. I’m still not
sure about the angle that you describe for first applying the
tool. It seems your describing a very low angle to the surface
of the metal. I’ve put a picture of what I think you are saying
at http://www.artsights.com/benchtricks . Let me know if that is
correct. I assume the tool is then swept around the stone in a
continous motion?

George Hebner
ghebner@artsights.com
http://www.artsights.com/ghebner


#4

Here is another procedure. Mark placement of stones with
divider. Drill holes with a twist drill, a bigger hole makes
seat drilling easier. Turn the stone upside down on your bench.
Pick it up with your mm. gauge. Push it out with your
fingernail. Find a setting bur or ball bur slightly smaller than
the stone with the mm. gauge. Drill the seat slightly deeper
than you will want the seat cut. Pick a 45 degree heart bur
smaller than the stone, it almost doesn’t matter how small but
not tiny, usually people just try to find a sharp one. Cut the
bearing so that the table is about flush with the surface, it
may be above the surface on a larger stone. Keep in mind that
you are trying to cut a bearing that is the same diameter as the
stone, don’t overcut. Pick up the stone with your wax and try to
fit it in, it is possible that the opening of the seat is too
small and it will have to be cut larger with the setting or ball
bur. You want it to almost squeak in. If it wont push in with
your fingernail, lift the edge of half of it by running one of
the points of your round pliers along the bearing. Lay or click
the stone in. Push down the edges with a pushing tool or a
hammer hand piece until almost tight. Don’t mush the edge flat
up against the diamond. Take a small flat graver, highly
polished, and go backwards at about a 45 degree angle until
tight. Then to make a perfectly round bright edge cut forward if
necessary. Just another method.

Mark P.


#5

i use a very simple method for setting melee flush to the metal
surface. after drilling the hole for the stone, i select a hart
bur that matches ( or is very slightly smaller than ) the stone.
if i can’t find a bur to match the stone, i find a stone to
match the bur !! i find it far easier, and faster, to buy melee
that is perfectly cut and calibrated and even though it may cost
more, the savings in time is worth the extra cost. i may have
hundreds of stones to set in one day, so i can’t spend a lot of
time rocking my bur around trying to cut a precise seat…and
all this rocking just gives me one more opportunity to mess up
the seat.

the stone should go into the hole with slight pressure…if
you’ve cut all your seats perfectly, all the stones will stay in
without burnishing. but burnishing will insure that they will
stay put! i use a polished flame-shaped bur…i buy them
ready-to-go from Frei & Borel…they’re not in the catalog, so
you have to ask for them. they are made by SWISS-BURS , style #
69. i use the 018 size. if the person at Frei & Borel doesn’t
know what you’re talking about, ask for John Frei.

use the side of the bur when you burnish…not the tip. ( this
could abrade the facets). use a little lube. i often hold the
burnisher at 2 oclock against the rim of metal around the stone
and rotate the piece in an engraving ball or benchmate.

flush setting looks best when you use small stones. stones over
3mm can be hard to set cleanly, especially for a novice. each
stone should have a burnished rim around it, and all the rims
should be the same size. all the rims should be smooth, even,
and polished. i have seen work where the craftsman had cut a
seat that was too large for the stone, then attempted to secure
that stone by burnishing the hell out of it ! don’t do it!
better to select a larger stone, or close the hole slightly by
peening around it ( if the surface will allow ), if you REALLY
screw up, you can always save your butt by drilling out the hole
and soldering in a tube…

like i say…the difference between a master and an apprentice
is that the master has learned how to fix his own
mistakes…!!!

doug zaruba


#6

Howdy all:

I learned that there were two ways set a flush stone- one way if
the stone was being mounted on a flat sheet- the second way if
the stone was being mounted on a curved piece like a ring. The
later way I was told to pretty much too make a very low seat and
then push the metal over the edges of the stone, burnish and
then push back the metal to create an nice circled window around
the stone. I am not too crazy about how this looks- the stone
looks “buried”. Any other suggestions?

DeDe


#7

Hello George! Sounds like you have my method pretty close. You’ll
change and modify as you set more this way. The very low angle
your understanding is correct. Just think of the logic of closing
the circumference of the hole with the described polished point.
In theory you might imagine the function as well as the purpose
of this low angle. It gives you metal to work with and burnish!
If you only tried the higher degree angle the metal would harden
and would be difficult to continue without calling up more elbow
grease! The preliminary, low angle approach alleviates this
hardening problem. When you bring up your angle and burnish at a
higher angle; the metal acts nearly like annealed metal, purely
because you haven’t hardened that direction yet. It really speeds
up the process. My final passes at say 70 to 80 degrees or so are
only for appearance, not to tighten. I’ve seen several new posts
on this, and there is more light shed on this method. Try a few
ways and see what works for you.

Tim