Was: Stone setting bur getting dull
i once read that a dull bur could be dipped in a strong acid that
would etch it back to sharpness. which brings me to the subject of
jewelers being frugal. how about some of your more (yes neurotic)
frugal behavior. could make for some interesting reading.
zev glickman
Zev Glickman b"h If you gotta drop your steel burs into strong acid,
I’d be extra careful with this manoeuvre. You might splash yourself
and get acid-burned. This is a very dangerous method to get into.
Just try buying new burs, it’s safer.
Gerry!
i once read that a dull bur could be dipped in a strong acid that would etch it back to sharpness.
that is not going to work, because acid would attack sharp edges
first. But on a subject of frugality, just because bur is dull does
not render it useless. In many setting situations, dull bur is more
useful than sharp one. Even after bur lost it cutting ability
completely, it still can be used as burnisher, with some
modification it can become rotary hammer, or a drill. It can be
forged into many small useful tools. I never throw out old drill, old
burs, and old files. Steel is to good to waste.
Leonid Surpin
that is not going to work, because acid would attack sharp edges first.
It works fine. You use nitric acid, it attacks all surfaces
simultaneously and thins the metal so it will in effect “re-sharpen”
the bur it also works on files. But the acid etched surface is not
smooth like the original ground surface but finely pitted so there
is more drag when the bur cuts and it dulls faster.
James Binnion
James Binnion Metal Arts
that is not going to work, because acid would attack sharp edges first.
Yes, if the bur is dipped directly in the acid without preparation.
But if you first clean the bur very well, and THEN apply something
that will act as an acid stop off agent just to the outer surface of
the bur teeth, the acid then acts only on the valleys. That undercuts
the worn tooth surface and in use, the previously dull edge can break
off at the undercut, giving you a marginally useful cutting edge. In
doing this, the size of the bur, and perhaps the accuracy of it’s
shape, is shot to hell, but you can still use it then to cut metal
The same method is sometimes used to “sharpen” dull files,
especially those with coarser teeth. Similarly, the above method
works more easily with coarse tooth burs. I tried it once using
simple magic marker (well, actually it was some sort of marker that
looked exactly like a Sharpie marker, but came from Radio shack, sold
as an etch stop off pen. It did work. Not all that well, and perhaps
hot worth the time and trouble, but it did, at least somewhat,
sharpen the bur.
Frankly, easier is to take one of the very thin seperating disks,
true up the edge, and use it as a fine grinding wheel to literally
sharpen the bur by regrinding it freehand. Not the carbon or vanadium
steel burs like the Busch burrs. They’re too fine a cut, and too
cheap to be worth the bother. But with some of the larger, costlier,
high speed steel burs, which have a much coarser tooth structure than
the Busch burs, it’s quite possible to return a bur from uselessly
dulled to useful. Use magnifiaction to grind the valley between
teeth, maintaining the angle. Grind the back of the tooth, not the
front leading edge. In doing this, you thin out the worn flat dulled
surface of the tooth. Take it to the point where there’s just the
faintest hint of the shiny surface that told you it was dull. don’t
fully grind it sharp. Done like this you end up with the same
dimensions and shape that the dull bur had, which might be more
accurate than the random inaccuracy you’ll get if you take the bur to
fully sharp teeth. The bur will be sharp enough to be useful again.
Slower than new, but usable. Small diamond grinding bits do the job
well also, if they’ve got a clean enough cutting edge to get into the
teeth.
Best, though, is not to waste your time sharpening your own burs
except in an emergency. Instead, put the worn (high speed, not
carbon) burs aside until you’ve got enough to make it worthwhile,
and then send them to one of the several suppliers that offers
sharpening services. What you get back are almost as good and sharp
as new, except they’re now slightly undersize. As Leonid and others
have pointed out, this is a rather useful thing to have. Bur sizes
midway between standard sizes gets pretty useful in some situations.
the cost for resharpening is much less than the cost for new high
speed steel burs, so it’s well worth doing.
Peter Rowe
i once read that a dull bur could be dipped in a strong acid that would etch it back to sharpness. which brings me to the subject of jewelers being frugal. how about some of your more (yes neurotic) frugal behavior. could make for some interesting reading.
The acid trick might sort of work for burrs, but when they are
toasted it is usually fatal. Acids are by definition nasty, I have
quite a collection but usually avoid using them.
One frugal trick is for dull files, clean completely and throw them
in the backyard grass to get them to rust (turn every day or so)
Vinegar with an excess of table salt will convert the rust to black
sludge (weak HCl substitute but it will still rest any nearby steel)
Brass brush, ultrasonic, steam, pressure wash etc and oil right away.
They will start to rust as you watch. A lot of work, the file won’t
be as good as new, but if you are really frugal it might make sense.
jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand
that is not going to work, because acid would attack sharp edges first.
It works fine. You use nitric acid, it attacks all surfaces simultaneously and thins the metal so it will in effect "re-sharpen" the bur it also works on files. But the acid etched surface is not smooth like the original ground surface but finely pitted so there is more drag when the bur cuts and it dulls faster
Interesting, Jim. Long time ago, somewhere, I’d read about using
acid to resharpent burs and files, and that source, maybe one of the
old George Gee books or something else from the early 1900s or so…
whatever it was specifically wanted you to apply some sort of stop
off to the tips of the teeth. I think wax was suggested, but don’t
remember. I’ve tried that a couple times, but don’t usually bother.
As I noted in my own comment to leonid’s negativity, I had some
marginal success with the sharpie style acid resist pen from radio
shack, using HCL. Never tried it with nitric, nor without the stop
off.
Proving once again that sometimes I should refrain from assuming
that what I’ve read in some old book is the whole story.
Does your nitric trick work on High speed steel too? The dull burs
that bother me the most frequently are the HSS ones…
cheers
Peter
Interesting, Jim. Long time ago, somewhere, I'd read about using acid to resharpent burs and files, and that source, maybe one of the old George Gee books or something else from the early 1900s or so... whatever it was specifically wanted you to apply some sort of stop off to the tips of the teeth. I think wax was suggested, but don't remember. I've tried that a couple times, but don't usually bother. As I noted in my own comment to leonid's negativity, I had some marginal success with the sharpie style acid resist pen from radio shack, using HCL. Never tried it with nitric, nor without the stop off.
There are several acids that will work HCL or Sulfuric I have even
seen some recommend vinegar. I have only tried the nitric. It thins
the edge and the trick can only be used a couple of times before the
edges are too degraded by the process. There are several processes
that folks use for this do a search on “acid sharpening files” on
the web and you will see many ways to do this. There is even at least
one company out there that offers this as a service they call it
“Liquid Honing” they sharpen many types of tools with this process.
Does your nitric trick work on High speed steel too? The dull burs that bother me the most frequently are the HSS ones...
Yes it works with HSS.
You need to constantly check the progress of the etch or you can
ruin the tool if it is left in the acid too long.
Jim
James Binnion
James Binnion Metal Arts
There are several acids that will work HCL or Sulfuric I have even seen some recommend vinegar. I have only tried the nitric.
Before we get too far in this topic, someone needs to define
sharpening. As I said before, the acid attacks edges first. Because
bur edge (any edge for that matter), if magnified will look like a
serrated blade, acid will consume protruding parts, and at the same
time would create new ones (bur diameter is reduced ). The problem is
that nitric acid damages steel structure and new teeth are weak, so
the sharpening effect is very short lived. It is probably wrong to
call it sharpening, the more accurate description would be that acid
treatment imbues burs with scratching ability.
If we consider price of acid, time, and all other troubles, simply
buying a new bur is far more preferential solution. Files are another
matter, because teeth are larger, so they retain most of the strength
(but not all), also cost files are higher than acid, so it does
make an economic sense.
Leonid Surpin
These folks resharpened a few of my files with good results…
Boggs Tool Processing & File Sharpening Co.
14100 Orange Ave., Paramount, CA 90723
800/547-5244, 562/634-1081, Fax: 562/634-0839
Sharpening of all types of hand files, rasps, burrs, end mills,
routers, countersinks, counterbores, spot facers, and reamers to
.005 inch for a fraction of the cost for new. Ask for their FREE
sharpening coupon. Brochure available.
Jeff Herman
If we consider price of acid, time, and all other troubles, simply buying a new bur is far more preferential solution.
I’m all in favor of saving money but I’m more in favor of having the
right tool, right now.
Proving once again that sometimes I should refrain from assuming that what I've read in some old book is the whole story.
Old way of trying to sharpen things - I always thought it was TOO
frugal and gives you a lousy file in the end…
But - I will tell the story of the man who’s widely considered the
finest diamond setter in Northern California… He uses the acid
method on burs to get fractional sizes of burs. He’ll buy a 1.8mm
bur and acid burn it to get a 1.78mm bur. It might seem pretty anal
to some, maybe, but then again that’s part of why he’s considered
the finest diamond setter in Northern California…