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Things to do with old worn burs


#1

One of my favorite things to do with old worn burs is to use nitric
acid to sharpen them! I use an etching solution of approximately 20%
nitric acid to water and dip the cutting head of the bur for about 10
to 20 seconds. When I first read about this process, I kind of
laughed thinking that it might shrink the bur in size but probably
not sharpen it much. Months later I had to pave’ set about 200
matched stones into a leopard broach and didnB9t have the right size
bur. Luckily I remembered the nitric acid trick and decided to give
it a try. It worked great, it shrank the bur in size and to my
amazement it was as sharp as new. The 20% etching solution works
at room temperature for tungsten burs but if you’re going to use it
on high speed burs you have to heat the solution a little to get the
same cutting action.

I believe the process works because the teeth on a bur are slanted
with one side of the angle slanted more than the other. Since
nitric acid mainly etches straight into the metal and doesnB9t
undercut, itB9s the long side of the tooth on the outside edge that
gets removed , shrinking the bur in siz e and removing the worn edge.

Here’s how I’d do it, first use an ultrasonic or steamer to make
sure the bur is clean. Wear safety glasses and obey the rules of
working with acids. Dip the cutting head of the bur into the solution
of nitric acid for about 10 to 20 seconds then neutralize in baking
soda and water. You can repeat the process if the first etching
didnB9t do the trick. Use a ultrasonic one more time to removes any
scale that might be left from the process. Oil th e bur before using.

Blaine Lewis
New Approach School for Jewelers


Now offering an 8 week state certified
Jewelry Technician Program.


#2

Hey , I love this idea of Blaine’s… It works , I saw it… The bur
is really as sharp as if it were brand spanken new… I have yet to
get my hands on any nitric acid however… Blaine, if Iam not
mistaken, won’t this work on files as well??? Marc Williams


#3

Hi Blaine,

Thanks for your proven recipe for sharpening burrs using nitric
acid.

I’ve never tried it, but have heard the old timers used to use this
same technique to ‘sharpen’ files as well.

Another use for the acid bath is to taper the ends of wire for
inserting into a draw plate when drawing wire. The acid needs to be
changed for gold however. Thank John Burgess for this suggestion.

Dave


#4
   I've never tried it, but have heard the old timers used to use
this same technique to 'sharpen' files as well. 

Hey c’mon, it’s not just the old timers. the method’s been
published widely for a long time, though not widely touted or taught
in the schools. but for many of us, it’s been routine for years, and
I’m not all THAT old (I hope). It works better for burrs than for
files, as files seldom seem to cut quite as evenly after acid
sharpening, especially fine cut ones. Coarser files work better. they
don’t stay sharp quite as long (burs either, though less noticably)
since the etch tends to produce a “wire edge” on the cutting edge
that is initially sharp, but breaks off, leaving a less sharp edge.
On a bur, you don’t notice it so much, but with a file, sometimes you
end up with a sharp, but scratchy file that doesn’t leave a surface as
even as you’d like. Also, nitric isn’t the only acid that you can
use. HCL works well, and in a pinch, I’ve even used some older
pickle, though that isn’t as effective…But on a dull burr when you
don’t have another acid right handy, or another of the right size
bur…

       Another use for the acid bath is to taper the ends of wire
for inserting into a draw plate when drawing wire.  The acid needs
to be changed for gold however. 

or gold use aqua regia. But faster even than just a plain acid etch
is an electroetch. You can even use just standard electrostripping
solution. Some of them will work with either silver or gold.
Usually cyanide based though… With silver, nitric and low voltage
is very fast. With gold, aqua regia with low voltage is also
efficient, though a good cyanide electrostripping solution is also
quite fast here. The method is less effective on larger wire sizes,
but when the wire gets fine enough that it’s hard to hold and hard to
file a new point on, 'cause it’s too fine, then the electrostrip
methods really shine, and are quite fast.

cheers
Peter


#5

Dave please contact me. We have been a Locadios class together.I need
to get some of your wire jigs for square wire and the you items for
pulling chains. i am in Phoenix 602404-1966 Jerell skirboll aka judy jones on
orchid


#6

To make the most wonderful jig for wire forming, take your old or
worn out burs and cut off the heads. Grind down any sharp edges.
These now become the pins (pegs) for a wire shaping jig. An old
piece of flat wood can become the base for the jig. Simple grid out
the wood by using a small piece of graph paper glued with rubber
cement to the wood. Then drill holes, through the paper to fit the
newly made “pegs”. The pegs can be moved around to make any shape.
Make sure that the drill size selected will fit the pins snugly so
they do not move around, and making sure that you drill deep enough
to give the pegs some “tooth” If I find a pattern that I want to keep
repeating again and again, I get a small 2 x 4 block, drill holes
along the 2 by side. I then permanently glue in the pins with
epoxy. I like using the side of the 2 x 4, it gives easier access to
a work surface and I find I can make the links faster and with less
fuss. Using this side of the wood also allows me to work off one
continuos strand of wire, cutting only after I have formed the shape
or link. Beth Katz


#7

This is more of a “Handy use” kinda thing…

I made the same kind of wire jig using a 2X4 and steel dowel pins,
which one can get at the hardware store…I suppose if one was
patient one could also cut up a length of drill rod… You can get
different lengths and diameters if desired…same process used in the
drilling…

Gary W. Bourbonais