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Drilling stainless steel


#1

Hi everyone,

I need to drill some 316L stainless steel balls 3/4 of the way
through that are about 5/32" up to 5/16" in diameter… i’ve tried to
drill these with my drill press but the bit just doesn’t want to
center and slides off the sides of the ball… what can i use to
drill these perfectly in the center??? also i tap these with a 00-90,
0-80, or a 1-72 tap… i’ve broken 2 taps already from accidently
moving from side to side… i tried holding the tap in my drill press
and spinning the chuck manually, but it still broke it… what can i
do so i don’t break these??? i’d really like to get this jewelry
makin’ thing down, so any help would be GREATLY appreciated… thanks
to everyone who’s helped w/ my questions in the past… you don’t
know how much it means!!!

David Basile
Gen-X Jewelry
www.gen-xjewelry.com


#2

David, You need to centre drill first with of course a centre drill
which will guide the point of the drill to the correct location. MSC
has them, so there is no problem finding them. Alternatively you could
use a flat end mill which is more sturdy and will not walk like a
drill to start a point of entry. Make sure your drill is a split point
as this increases the ability of the drill to start a cut immediately
at the point of entry.

Best Regards.
Neil George-
954-572-5829


#3

David,

I have successfully drilled larger (3/8") stainless balls by securing
them tightly in a portable Dremal vise. Remove the rubber edge
protector and there is a nice “V” slot for the ball. You can crank
the metal edge tightly against the steel and I have found that it will
not make a mark on the ball. Once the ball is in place, I punch the
ball with the hammer and tap. I set the vise under the drill press at
high speed. I use cobalt drills #55 and I have been surprised at how
easy the stainless drills. I buy my cobalt drills from MSC Industrial
Supply Co.800-645-7270. I think the strength of the cobalt helps the
process greatly. Good luck and let me know if you need more advise.

Rebecca.


#4

David,

It is very difficult to drill into a sphere of 316 Stainless steel.
The main reason for the difficulty is in locating the center of the
ball with the drill bit. It is advised that you use a lathe (and not
a drill press). Hold the ball in a small 3-jaw chuck (which will
automatically center it) and you MUST start with a center drill, this
is a small type of bit that will start the hole without sliding off of
the surface. Then switch to your drill bit and finish the hole to the
desired depth, use plenty of tap-magic cutting fluid (or something
similar). In order to tap the hole with threads you MUST support the
opposite end of the tap and keep it straight and use plenty of cutting
fluid. If you look at the handle of your tap you will notice that it
has an indentation. This is so that you can hold that end straight
with the tailstock of the lathe, or a center point in a drill press.
It is a very easy job if you have the right equipment, but a real pain
if you do not.

HTH,
Daniel J. Statman, Statman Designs
http://members.rennlist.com/statmandesigns


#5

I use my Taig lathe when I have to drill balls, but you probably
don’t have a lathe lying around… Best to get a really tiny combined
drill/countersink (#00) and use it to spot drill the bead before
drilling with the drill bit. To get the bit centered, put a 6" steel
rule between the bead and drill/csk tip. Using light pressure, see if
the rule is level, move the bead until the rule is level in both x and
y axis. (Have the drill bit touch the 3" mark) It helps to have a x/y
table (another thing you probably don’t have lying around) to adjust
the bead position. Also If you can make Aluminum vise jaws for your
drill press vise that have a dimple on either side to hold beads that
will help. Use a tiny tap wrench, and lots of lube, and don’t drink
coffee beforehand when tapping 00-90’s turn, back up, turn, back up,
slow and steady. You might want to see if you can get “fluteless” taps
as they are a bit stronger. Good luck


#6

First I should say that I haven’t tried this, but I’ve done lots of
machining. If you have a drill press it seems like the problem would
be solved by center punching the ball first, then clamp a thick plate
of aluminum or brass under the drill press and drill a hole at least
3/4 of the ball’s diameter in that plate, and don’t move that
alignment. Then set the ball in the hole and align a small sharp bit
with the centerpunch mark by rotating the ball. It should drill
straight through the diameter. Alan Heugh


#7

David – Tapping stainless 303, 316, or any other stainless is
difficult. It work hardens when you try to drill it, and tapping it
in these small sizes is impossible. I suggest you tap a small piece of
brass or aluminum about 1/8 diameter and bond it in for the thread.
You need to start the hole with a center drill (any hardware store) ,
and buy a carbide drill of the proper size for the rod. Rough up the
rod for a good bond. To prevent work hardening, don’t try to drill
with a light touch, get a good chip and drill to the bottom. John
Burton ( boy engineer)

To the gal who is trying to print just a section of the digest,
highlight the section you want and COPY it, and then PASTE it in a
file under Jewelry Tips (Word or what ever). This was suggested to me
by Hanuman of Orchid.


#8

Just a couple of points to add to the good advice about starting with
a centre drill and so on.

Firstly, stainless steel has an absolutely ferocious tendency to work
harden. If the drill rubs rather than cuts, just briefly, it will
harden, and be impossible to drill in the sizes you are interested in.
So, you need really sharp drills, and a deft touch on the feed lever
of the drill press … the drill must be cutting all the time it is
in contact with the stainless.

Secondly, remember that this stainless is tough stuff. Make life as
easy as you possibly can for the tap. That means using a lubricant
(“proper” stuff is available from engineering suppliers, but just
about any oil will help somewhat, and use it on the drill too), and
look to the size of hole you are drilling. For your application (I
assume we’re still talking body jewellery here?) where there will be
no great mechanical stress on the threads when in use, you could
make
a slightly larger hole than that recommended in the tables, and so
have less metal for the tap to move. – Kevin (NW England, UK)


#9

New to stainless steel, advice please.

I am drilling holes between 1 mm and 2.5 mm diameter through 14
gauge stainless steel.

Sometimes the bit picks up just right and cuts it’s way through.
Mostly, after a poor start, the bit stops cutting and the stainless
work hardens preventing any further cutting. I have been using HSS
bits and diamond coated bits. The HSS work best but I’m sure it must
be easier than this? What am I doing wrong?

Have resorted to punching the holes through hot metal, not a very
good answer!

Thank you.
Nick


#10
I have been using HSS bits and diamond coated bits. The HSS work
best but I'm sure it must be easier than this? What am I doing
wrong? 

Diamond coated bits are super ineffecient on stainless…they just
get clogged and do you no good. HSS bits are good, but not the best.

What I recomend are solid carbide 2 flute 140* straight flute bits.
Look at mscdirect.com their big book page # 117. A couple of down
sides…1) They are not cheap, 2) You will need a small 3 jaw chuck
in your foredom/drill press to use them…and 3) did I mention the
are not cheap?

What I really like about these, is they are specifically designed
for drilling hard/tough metals. The straight two flute design makes
them a stronger bit than a spiral flute, you can put some side load
on these bits and they will take the load. They dont clear chips very
well, so be concious of that. If you take care of these bits, they
will last a long time.

I swear by these, especially if you are drilling by hand.

P@
www.patpruitt.com


#11

Speed control and constant feed are critical in drilling stainless.
Too fast and the bit will dull rapidly not enough feed and the bit
will spin instead of cutting and work harden the stainless to the
point that nothing short of a carbide drill will cut it. Diamond is a
very poor choice for any steel cutting. It tends to alloy with the
iron and gum up the cutting edge. For grinding you can get away with
diamond abrasives if properly lubricated and the steel is hard enough
but it is a poor choice for drilling or other types of machining.

Anyway for a 1 mm hole in 300 series stainless the recommended max
speed is 4400 rpm with a feed of .014 mm per rev or 71 mm per minute
so my guess is that you are not feeding fast enough. With a slower
speed the feed per minute decreases so at 1000 rpm you are looking
at 16 mm per minute and a feed of.016 mm per revolution. A 2.5 mm
drill is suggested at 1780 max with a feed of .040 per rev.

James Binnion
James Binnion Metal Arts


#12

When drilling either stainless or tool steel, it is easy to go wrong.
Touching the surface lightly with the bit or denting it with a punch
will workharden the metal. This is just at the surface but hard to
drill thru. When you start to drill, you must sort of tap the surface
with the spinning bit and apply pressure immediately. Whether using a
drill press or by hand, that immediate firm push is the secret. It is
almost as though you are breaking thru the hard layer.
microscopically thin, but a layer none the less. Try it.

Tom Arnold


#13

When drilling, the only thin a dull bit will cut thru is a finger.

Have fun.
Tom Arnold


#14
Anyway for a 1 mm hole in 300 series stainless the recommended max
speed is 4400 rpm with a feed of.014 mm per rev or 71 mm per
minute so my guess is that you are not feeding fast enough. With a
slower speed the feed per minute decreases so at 1000 rpm you are
looking at 16 mm per minute and a feed of.016 mm per revolution. A
2.5 mm drill is suggested at 1780 max with a feed of.040 per rev. 

Thank you Jim, my problem is that I am just not well enough set up
to control these parameters. The lathe I have is too cumbersome. But
it may well come down to sorting this out as I get more involved
with stainless. Meanwhile I get the principles and for the time
being will have to continue workingby hand.

What I recomend are solid carbide 2 flute 140* straight flute
bits. Look at mscdirect.com their big book page # 117. A couple of
down sides...1) They are not cheap, 2) You will need a small 3 jaw
chuck in your foredom/drill press to use them...and 3) did I
mention the are not cheap? 

Well yes Pat, you did mention they weren’t cheap… but that in no
way prepared me!!

I couldn’t find diameters at mscdirect below about.09" which are too
big for the job in hand. I have however found reground tipped carbide
bits 0.6 through to 1.2mm used by the electronics industry and at the
price $21 for a pack of 10 they’ve got to be worth a try.

Thank you
Nick


#15
my problem is that I am just not well enough set up to control
these parameters. The lathe I have is too cumbersome. But it may
well come down to sorting this out as I get more involved with
stainless. Meanwhile I get the principles and for the time being
will have to continue workingby hand. 

You can do it by hand just keep the speed and feed in mind and do
some practice runs to get a feel for proper cutting action. The
biggest thing is to never stop feeding the drill into the work. If
you allow it to spin without cutting while it is in the stainless it
will be a problem.

James Binnion
James Binnion Metal Arts


#16

Hey Nick

I use Cobalt drills for Stainless steel … they cut at pretty high
speeds… You need to get as close to the recommended speed as
possible.

Best,
Bruce


#17
Well yes Pat, you did mention they weren't cheap... but that in no
way prepared me!! 

And for some reason, people thing working with stainless is cheap
and easy… :wink:

I have however found reground tipped carbide bits 0.6 through to
1.2mm used by the electronics industry and at the price $21 for a
pack of 10 they've got to be worth a try. 

These are super awesome…if you have CNC parameter control that
is…I will tell you now, the circuit board drill bits are by far,
the easiest bits to break and shatter when drilling by hand. They
will carry absolutely no side load in the tiny sizes. It would be
best to chuck these up into a drill press, no matter how cheap/crappy
the drill press is, just so you keep the drilling verticle. With the
1/8" shanks on them, all drill presses should accomodate them.

Ive got some 0.46mm (0.018") carbide drills in bulk for a project
that requires some tiny holes… in stainless…so im right there
with you.

P@
www.patpruitt.com


#18

I drill relatively small holes ( up to 1/2 inch) in stainless tubing
and sheet all the time.

Here’s my formula for success:

  1. use cobalt split point bits from a quality supplier ( not cheap
    chinese junk)

  2. continuous moderate pressure (james Binion’s comment about not
    letting it spin is correct!)

  3. no lubricant at all

  4. a vise to hold the work if possible

  5. centerpunch your spot before drilling

I really dont’ think you need the expensive carbide bits… though
they are good. they may shatter if you get “hung up”. Also, i think
the 4k rpm range is excessive, based on my experience. Likely to burn
up bits, i’d say. Overheat your bit and it’s toast.

i’ve been experimenting bringing stainless into jewelry… and it’s
pretty neat.

Polishes GREAT and has the heft close to white gold.

One recycling source for ring shank material in stainless is the
"backbone" of modern automobile windshield wipers. these things have
a strip of stainless that is commonly thrown away without a second
thought. Anneal before bending.


#19

I am surprised that no one has mentioned lubrication! Proper
lubricant and lots of it is necessary. The Anchor Lube product we
supply for titanium is highly recommended for stainless steels. It
can extent bit life and prevent freezing the bit in the hole.

Bill
Reactive Metals Studio, Inc


#20
Also, i think the 4k rpm range is excessive, based on my
experience. Likely to burn up bits, i'd say. Overheat your bit and
it's toast. 

The drill speed is a matter of diameter and material being cut and
the drill bit material and geometry but for a standard metal cutting
drill bit the following numbers are considered to be about optimum.
In 300 series stainless a 1 mm HSS drill bits optimum speed is 4497
rpm a cobalt bits speed is 4950 rpm and a carbide bits speed is
16,872 rpm. In mild steel double those numbers and copper runs best
at twice the speed of what you would use for mild steel and titanium
is best at about 3/4 the speed you would use on stainless. So a wide
range of speeds. A 2 mm bit needs to run at half the speed of a 1mm
and a 4 mm bit is run at half the 2 mm rpm etc.

The speed and feed together control the chip size. If you go slower
there is a tendency to cut too large a chip and that can break either
the cutting edge or the whole bit. This along with poor side loading
ability is why carbide twist drills break so often when they are used
in tools that don’t have the ability to provide the correct speed and
rigidity. The proper speed and feed make the tool last longer and
give the best productivity.

James Binnion
James Binnion Metal Arts