It is easier to drill work-hardened metal than annealed.
From this observation and others in your post you obviously haven’t
drilled much stainless steel
James Binnion
James Binnion Metal Arts
Sandra,
I've been going through drill bits like water - they lose their bite so quickly. I drill under water with either a Dremel or Foredom and a #67 bit. The last run I did ended up with dull bits after every 20 holes.
ALWAYS buy the best cutting tools you can find. The difference in
quality between an ‘jewellery’ priced carbon steel drill and a cobalt
one from an industrial supplier is about 1000%, but the price isn’t
http://www.use-enco.com is one supplier I use reasonable prices
(unless you are a tool junkie) and so far good service.
And learn to sharpen them, sanding or diamond disks work well. You
can also use a cylindrical diamond (I’d have to practice a bit in
order to describe the technique, one of those auto pilot things) No
fancy jigs required although a pin vice helps. Just copy the angles
from a new drill or buy a bigger one (8mm ?) as a reference sample.
Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand
Margaret,
Can you describe how you do this? Do you sharpen just the tip end or all along the cutting edge as it spirals up the bit? Please explain, this seems like a great tip to use.
I’ll try,
The tip of a drill is composed of two flat graver cutting edges.
They are twisted together and joined at the right side. of each,
forming the center of the drill bit. These two edges do all of the
cutting. Looking straight down the length of the drill, you may
notice that the end forms a shape very much like a pair of fan
blades. The forward edges are all that need the new edges. They need
to be shaped so that when the bit turns, it will tend to dig into the
work and pull the chips out of the hole. I will usually start by
deepening the groove between the two blades thus creating a sharper
point.
This is very hard for me to describe and I hope that you will take
this in hand with a new drill bit and study how it works before you
poo poo the process. I use a seperating disc, because it profides a
lot of control and speed for thte small amount of material involved.
Burned bits will need to be broken off and reshaped.
Good luck and i hope this helps
Bruce
Bruce Holmgrain
JACMBJ
From this observation and others in your post you obviously haven't drilled much stainless steel
The drilling of any material are controlled by such variables like
angle of attack of cutting edge and a set of variable which
encapsulates: diameters, drill geometry, rotational speed, material
itself, and etc. The point is that in practice only angle of attack
is under control of the user, while the other parameters are part and
parcel of the task at hand. As little as my experience in drilling
is, I can assure you, that there is an angle of attack which is
suitable for drilling stainless still and/or any other material of
similar properties.
Leonid Surpin
To Holly and all… I’ve been away, and there’s been much about
this… But two thoughts:
Sharpening wire size drill bits with a separating disk is pretty
common practice, and easy to do with a steady hand. I use a
Crystallite diamond wheel because I have it, instead.
More to the point - many here rely on some jewelry supplier or
another - often Rio - for absolutely everything, which I’m familiar
with but it’s a mistake, really. Rio doesn’t have LOTS of stuff, and
neither do the others. When you need serious steel stuff - drills,
cutters, machinery, you’re better off going to the steel business
for it.
Many here like McMaster-Carr http://www.mcmaster.com/ I like
https://www.travers.com/ a lot. There is http://www.enco.com, which
tends to the cheaper imports. Even grizzly isn’t too bad. Another
biggie is http://www1.mscdirect.com/cgi/nnsrhm and there are many
others - http://www.wttool.com/, http://www.reidsupply.com/.
Actually, your local Home Depot or Ace hardware has some pretty
decent drills in a limited size range. Bosch… BTW,
http://www.littlemachineshop.com/ is most useful, too, but generally
for other reasons - small scale tooling. Any of those carry drills
that are specific to metals and/or applications running from circuit
board to aerospace. Don’t be afraid to branch out with your sources.
Jewelry = jewelers suppy, steel =steel supply, etc.
Hi Folks…
I drill hundreds of holes in the copper and am wondering if there are any recommendations that might help me get longer use or better use from my bits so that I can drill more pieces before having to throw away a dull bit.
With copper, make sure you’re using brite (shiny) or TIN drills…
Gary W. Bourbonais
L’Hermite Aromatique
A.J.P. (GIA)
Leonid,
Recommendation "not to use center punch" because it toughens the metal is a nonsense, because you do want to toughen the area that you drill.
Twist drills flex and take the path of least resistance. Trying to
start a hole in the hardest part of the metal (centre of the punch
park) is asking for problems.
Besides it is difficult to centre punch dead on. With a little ball
burr you can drag the indentation to the exact position. I’ll use a
centre punch on big crude work when I don’t really care exactly where
the hole is (2" steel angle iron ) but not on jewellery.
Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand
Buy a high speed drill press, if your drilling that many holes, its time to make the investment. There are several nice ones out there for under $1K. Lastly use a cutting lubricant, not water, my guess your getting the cutting edge too hot and its loosing its edge.
Thanks to all of you who replied privately and on-line. There are
several ideas that I will try, I have my next shipment of 100’s of
blanks arriving within a week or so and each black gets two holes, so
I’ll have lots of opportunity to try a variety of techniques. And I
have a drill press, but was having issues with that also since it
really isn’t made for drill bits as small as what I’m using.
Experimentation time will continue and thanks again for the input
from all of you.
Sandra Graves
Blog at http://sandragravesisisrising.blogspot.com/
I drill hundreds of holes in the copper and am wondering if there are any recommendations that might help me get longer use or better use from my bits so that I can drill more pieces before having to throw away a dull bit.
I’m coming in late on this thread, but I’m not sure this has been
mentioned-- please forgive if redundant.
A lot of folks don’t realize the importance of lubrication on bits,
burs and blades. Most of us have been taught to lube saw blades (I
prefer beeswax-- hate that crumbly, useless burlife), but I think
many don’t lube for drilling, and that will do in your bits real
fast. People also run their drills way too fast. This is a “double
whammy”.
Beeswax is an OK lube for drilling, but I now prefer something that
was recommended here on Orchid a few years ago-- thread cutting oil.
I found it (by asking, not by looking!) at my local hardware store.
The small bottle (maybe 6 oz) will probably last the rest of my
life. I keep a little tiny container-- one of those tiny round
aluminum “watchmakers” jars with a glass lid-- on my bench with a
cotton ball soaked in oil and poke my drill or bur into in before
using. That way, when I knock it off onto the floor there is no
spill, cuz I never knock it off when the lid is on, of course!
Noel
Do you sharpen just the tip end or all along the cutting edge as it spirals up the bit?
Bruce already said some about this - chuck the separating disk (I
use diamond, again) and hold the bit with your other hand. Touch
each cutting face to the wheel until it’s sharp and even. Getting it
right takes some knowlege and practice (and a vise grip hand), as
it’s easy to get the tip on the wrong center or off center…
The flutes on a drill bit are channels to let the chips travel away
from the work and prevent fouling. They are only incidentally sharp
from cutting them originally - they shouldn’t be sharpened, mostly
because it will change the geometry of the drill. Milling cutters
look similar to drills, but the flutes are actually cut, angled and
relieved to be cutting edges - a whole different animal…
Twist drills flex and take the path of least resistance. Trying to start a hole in the hardest part of the metal (centre of the punch park) is asking for problems.
I know what are you referring to, but without drawings it is not
possible to discuss this. It relates to “how to correctly sharpen
drill”. It is much more complicated subject than it appear to be. All
I can suggest is get hold of decent machinist manual. Not the one
which only have tables, but the one which explains how tables were
derived.
Besides it is difficult to centre punch dead on. With a little ball burr you can drag the indentation to the exact position. I'll use a centre punch on big crude work when I don't really care exactly where the hole is (2" steel angle iron ) but not on jewellery.
Yes, marking holes with a punch is difficult and I suspect that
attempts to avoid doing it are rooted in that difficulty, but it has
to be done. Most trouble in drilling is not because material too
hard, but because it is too soft, so localized work hardening is
beneficial. No matter how much of work hardening took place, the
drill
will be able to take it, providing it is sharpened correctly. If
material too soft, drill bites too much and chip formation generates
forces which wear off cutting lip and would required re-sharpening.
Stainless steel does have properties which makes it unforgiving
material, but I do agree that it is more difficult to drill. It is
more difficult to drill if drill is not shaped correctly. Stainless
steel has low thermal conductivity. If there is heat generated during
drilling, the heat tends to be localized and it destroys cutting
edge.
The difficulty in restarting drill in case of slippage, is not due to
work hardening, but due to cutting edge becomes annealed during
slippage. The more you try, the more heat, the softer the edge and
it becomes a vicious cycle.
Let me give you one more example that we should not be afraid of
work hardening. In watchmaking, parts are first hardened and then
tempered to the blue stage. Only after that they are drilled and
shaped to final dimensions. This is done to avoid shape distortions
which always present in heat treatment. The steel tempered to blue
stage is much tougher than steel that was work-hardened, but
watchmakers successfully dealt with it, and so should we.
Leonid Surpin
A lot of folks don't realize the importance of lubrication on bits, burs and blades. Most of us have been taught to lube saw blades (I prefer beeswax-- hate that crumbly, useless burlife), but I think many don't lube for drilling, and that will do in your bits real fast. People also run their drills way too fast. This is a "double whammy".
This is true, but with stainless it is slightly different. Stainless
does not conduct heat well. So unless you drill when part is
submerged, or like in industrial environment where coolant pumped
constantly, it is more productive to concentrate on not generating
heat, than on trying to deal with it. That is not to say that
lubrication is not important. However lubricant should be capable of
withstanding high temperatures. Synthetic motor oil is a good
option. Before synthetic oil was available, we used burned motor oil.
Burned motor oil is the oil that was already used. When changing oil
in your car, save some of it. It is a very good lubricant for
drilling, thread cutting, and general sharpening.
Leonid Surpin
I keep a little tiny container-- one of those tiny round aluminum "watchmakers" jars with a glass lid-- on my bench with a cotton ball soaked in oil and poke my drill or bur into in before using. That way, when I knock it off onto the floor there is no spill, cuz I never knock it off when the lid is on, of course!
I have a similar container, but it is one of the small steel boxes
that parts used to come in, a 1 to 2 inch cylinder with a pull-off
lid. I poked a hole in the top with a nail and put cotton inside the
box, soaked in the oil of my choice. A drill bit or graver can be
dipped into the box, with the lid on. I think this is an old-time
jeweler’s or engraver’s trick that I learned somewhere. I use oil of
wintergreen, which is also supposed to help keep one alert.
M’lou Brubaker
Minnesota, USA
http://www.craftswomen.com/M’louBrubaker
Synthetic motor oil is a good option. Before synthetic oil was available, we used burned motor oil. Burned motor oil is the oil that was already used. When changing oil in your car, save some of it. It is a very good lubricant for drilling, thread cutting, and general sharpening.
Last thing you want when cutting metal is a lubricant. Motor oils
are designed to prevent metal to metal wear. Cutting oils are
designed for maximum wear (cutting) and to get rid of heat.
Production environment and flood cooling with water and maybe 5%
soluble oil (messy and totally enclosed large machines)
Stainless is a problem because it is tough, a poor conductor and
will work harden in a heart beat if the tool is not cutting. Spin the
drill without cutting and it will work harden so much that it can’t
be cut. Get too aggressive and you’ll burn/break any drill. Fun
stuff, but it is workable, just not the same as gold or silver.
Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand
Beeswax is an OK lube for drilling, but I now prefer... thread cutting oil. I keep a little tiny container...on my bench with a cotton ball soaked in oil and poke my drill or bur into in before using.
You know I can’t do that because, no matter how careful I am, I will
invariably put my spinning bur into the cotton and spray everything,
including myself, with oil. Not a pretty site.
I use Bur Life from Rio. I know it’s more expensive but I just don’t
seem to be patient enough (code for uncoordinated) to wait for the
bur to stop before plunging it into an oily blob of cotton. Ugh.
Mark
Foredom and a #67 bit. The last run I did ended up with dull bits after every 20 holes.
Sandra, just today I drilled 24 four mm deep holes in white gold -
almost 100mm of gold, with a #72 drill bit. I broke one, sharpened
once and then also drilled 24 more shallow holes in 14k yellow with
the same bit. The white gold is turning solid wire into tubing on a
bracelet, BTW.
So getting only 20 holes - presumably you’re talking sheet metal of
some sort - in copper means something is very wrong. And water’s not
the best coolant but it’s better than nothing. I also use bur-life
and I don’t care what it costs because mine is 20 years old…
I would suggest that it’s one of three things: speed, technique or
the bits themselves. Speed on a #67 should be the foredom pedal on
the floor. 10-15,000 rpm is just fine for that size. Technique means
letting the drill do the work, and don’t push too hard. I would look
at the bits themselves, though, because that’s a real short life. Try
high-speed steel or cobalt… Carbide is a thought but those sizes
will break if you look cross-eyed at them… Copper is prone to
spalling and things (it is “sticky”), but it’s easily drilled,
usually. Changing coolant to a real one (soluble oil) is a thought,
but I just can’t see coolant being the culprit with such a situation
- certainly it would help.
I use Bur Life from Rio. I know it's more expensive but I just don't seem to be patient enough (code for uncoordinated) to wait for the bur to stop before plunging it into an oily blob of cotton.
My objection to Bur Life isn’t the cost, it’s the way it crumbles.
Doesn’t seem to stick to the bur/blade/whatever. But to each his
own!
But here’s another solution. I have my students (who don’t have my
tiny container) put a single drop of lube on the bench and touch the
bur to it periodically. When it’s gone, put another. Just try to
remember to eipe up the residue at the end of the day!
And by the way-- yeah, I’ve done that. Flings the tiny container and
the oil all over the place, winds my bur up in cotton… Quite a
mess. I suppose if we adopt the recent suggestion of poking the bur
through a little hole into the cotton ball, or into just oil, then
the mess would be pretty limited. But who wants to change, right?
Noel
If you split point a drill it will cut better the center of most
drill really don’t cut well they create friction and not really cut
but the out edge do that’s why a pilot hole drills easier. and if
you prick punch it relieve the center and make the drill seem easier.
what little bit of stainless in compressing the metal the outer
edges of the drill will remove it. Also the flatter the angle of the
drill the harder the metal will drill and the softer the metal the
more angle you can have. When drilling hard metal if the angle is to
great it will catch the edge and snap the drill or stall the drill. A
quick way to check a drill angle is to put to Hex nut together like
for a 3/8 dia bolt the angle of the hex is the proper angle to drill
not to flat and not to pointy. The more you sharpen a bit the larger
the center web gets as they a tapered from the shank to the point
allowing rigidity and a thin enough point to drill. Most people when
sharpening a bit will get the heal of the cutting edge to high and
all that does is stop that side from cutting and generate heat. When
the drill has the point split there is a cutting edge that requires
less force, centers it self and if keep constant pressure the
cutting edge will stay cooler as fresh cooler material is force over.
a drill slipping and not fully cutting will generate heat and remove
temper from the bit and soften the metal. we found this out with
power rock cutting chisels they would generate enough heat to re
temper the chisel and soften them. We used to re forge the tip and re
harden and temper the chisel. My Brownpolymer does aid in the drill
as it will lube the center of a drill that has not been split pointed
and it lubes the heal helping in keeping the bit cooler. Not all new
drills are sharpen properly if the operator that was doing the
sharpening doesn’t dress his stone or is sloppy on his setup the
drill might not drill as good. I still take a new drill and re
sharpen to my liking. Other oils waxes can’t take the pressure and
wear off faster so they have to be reapplied the heat generated at
the cut area will smoke these and they turn to vapor. Just rub some
Brownpolymer on the Drill Bit it will stay on the drill land, cool
the edges while drill is drilling heat doesn’t vapor the polymer.
Also put some polymer on a flat material and press the drill down it
will force the polymer on the edge and activate to the surface of the
drill and wipe off the excess. The higher the Rpm the smaller the
drill but the drill has to be cutting or will just burn up.
Thanks Randy
AKA Enjen Joes
If you do like using the metal tin to hold oil for your burs, but
don’t like to have it flying off the bench - this may help: drill a
shallow hole in your bench just large enough to glue in one of the
super strong (but small) magnets flush to your bench.
I did this with one that is about 1/2" x 3/16".
This is useful for holding onto the tin, or holding bits or burs
that you want to keep in one place.
I also put a couple on the front edge of my bench to hold small
rulers.
margaret
I’d hazard it might be the cutting edge geometry, for copper and
copper alloys I was always told to give the edge a light rub with a
stone such that the rake of the edge was negative to neutral. I.e.
when you look at the bit head on the surface you sharpen normally is
what you see, right. The edge you want to stone the negative/neutral
rake onto is the one that is just inside the flute. Try to get it so
the included angle is closer to 90 degrees instead of the more usual
~70 odd.
Now the down side to this is that the bits you’re using are so small
that it might not be an easy thing to get right and also that you
can’t really use the drills without a total re-sharpening on any
other metal after setting the rake to ~90 degrees.
Another thing to try would be using lard (yes the animal fat) as
your coolant/lubricant, a little goes a long way with lard.
Cheers, Thomas Janstrom.
Little Gems.
http://tjlittlegems.com