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Drilling mystery stainless steel


#1

Hello!

I love to barter and I’ve traded for some really neat things in the
past. Printing services, other artist’s goods, even a pair of
contacts. This time it was for Chiropractic care (I’m learning a lot
about how to sit and work better).

Well, all seemed simple enough. I was to drill holes in 6 pairs of
1/8 thick stainless steel lightning bolts, add earring findings and
bing, bam, boom, he’s got earrings to give for the holidays. First of
all, I’ve never worked in stainless and I didn’t realize how hard the
metal was going to be. So I hopped on the internet to get some
advise, since my first attempt took way too long to drill.

  • Anneal the metal, slow cooling - check
  • Use good pressure - check
  • Lubricate - check
  • Slow drill speed - check
  • Broke 6 carbide drill tips - buy high speed drill bits instead per
    Rio

sales force advise - check, check

Well, now I’m waiting for my NEW drill bits to arrive. Any advise on
how to drill these buggers more efficiently with the tools I have.
(brute force, dremel, torch, kiln, drill bits) (Note to self… any
time a thought enters my head that starts, “That’s easy, all you
have to do…” or “Bing, Bam, Boom… Walla” a red flag should go
up. Nothing comes that easy, you should know that by now!)

Holly


#2

Ok first off what kind of stainless is it? Most likely it is an
austenitic alloy (304, 302, 316 etc) as this is by far the most
common type. So to anneal these types of stainless it needs to be
heated to above 1750 F and water quenched not slow cooled. Second
when drilling stainless you must have a continuous cutting action.
If you allow the bit to spin and not cut it will work harden the area
the drill bit is rubbing on and then you will not be able to cut it.
The slow speed info applies to high speed steel drill bits. Carbide
does not cut very well at low speeds and is so brittle any side
pressure will cause them to break. Your best bet is to use a drill
press but if you don’t have one you need to minimize any side
pressure and try to drill with a continuous chip coming out of the
hole. If you need to stop make sure to bring the bit out of the hole
while turning and as rapidly as possible.

Stainless can be quite frustrating if you are not used to working it.

Good luck,
Jim

James Binnion
James Binnion Metal Arts


#3

Hi Holly:

1/8" stainless, even 400 series, shouldn’t have been that big of a
deal. From what you wrote, you’ve got most of it right. Lube, slow
speeds, high pressures. That should do it.

The question you didn’t answer was ‘what diameter of hole’? Teeny
little holes take surprisingly high speeds.

I’d also be doing this in a drillpress, not a dremel. If the holes
are small (sub .100") and your hand wobbles even a little, you’re
likely to snap the bits.

In a drillpress, the technique would be to ‘tap’ at the hole. Drill
hard (ish) for a second or three, then back off to let the bit cool,
and re-lube the hole. Then do it again, and keep doing that until
you get through. Of course, locking the part down is key for making
that work. (Another reason why drillpresses are better than doing it
by hand.)

Stainless likes to work-harden if you don’t keep the bit cutting
freely, so don’t let the bit just sit in the hole spinning. Make it
cut, or get it out of there. If it stops cutting unless you really
force it, replace it. Lube early, lube often. I like the liquid
burr- life stuff.

For whatever that all’s worth.

Regards,
Brian Meek.


#4

Hi Holly,

I just made the same mistake…

Carbide bits are not the best option. See if you can find some drill
bits by the name cobalt. They work very well with stainless, I was
shattering a bit per hole in 3\16 inch thick stainless before and
now I can cut 30 to 60 holes (regardless of annealing or oiling) per
bit.

Christine
www.christinebossler.com


#5

Hi Holly,

I had some bad experience with stainless steel too… Here is the
method I use for holes like 0,8 millimeter: Use HSS drills avoid
Tungsten and carbide, they are way too brittle and the stainless
steel tend to stick to the drill (same for gravers when come the
time to set stones in that type of metal…). I use Methyl
Sallicilate as lubricant (yes the one that is used for muscle
onguent… I don’t know the proper therm in English, sorry) and a low
spinning speed (let say 800 to 1000 rpm max). I never try to drill
the hole at once (because the lubricant evaporate!)… Also check the
sharpness of your drill from time to time.

Et voila!!
Hope it’ll help.

Best regards,
Ced


#6

Are you sure that it is steel? There is a factory in my city of
Kokomo, IN- Haynes International, that produces high tech
metals(don’t know names of them) that are darn near impossible to
tool by traditional means. Many of these metals are used by NASA,
etc… About 20 yrs ago, a Haynes employee brought in a scorpion
(about3x5") that he had stolen & cut out at work, wanted rubies set
for eyes. After several broken bits I finally had ever so slightly
made small holes, not deep enough to actually set stones into, so I
got the guy to agree to allow a couple of red foilback stones to be
glued on. I was certainly glad to see that one go away. I probably
wasted $100 worth of time and drill bits.


#7
Stainless can be quite frustrating if you are not used to working
it. 

It can still be frustrating even when you ARE used to working with
it… :wink:

Ill prempt all of this by saying this is only my experience…and I
only resort to free hand drilling when the piece cannot be solidly
clamped in the milling machine.

One thing that has helped me a lot when free hand drilling small
holes with a foredom unit in stainless steel (300 series) is the use
of a 2 flute 140* straight carbide drills. You can get these in wire
size bits down to #60 (0.040"). thru mscdirect.com (big book page
120-121)

The main advantage of these particular bits is the geometry of the
bit itself. The 140* point is pretty darn strong, Using a center
punch, or starter dent, is highly recomended as the tip will tend to
wander on start due to the wide angle.

The straight flute design lends itself to making a sturdy bit as
well, it can take more side load abuse than a standard twist carbide
drill before it fails. I say this with the understanding that almost
all small carbide twist drills snap with the slightest side load
applied, and drilling freehand, this will happen. Honestly, this was
a huge suprise, I was expecting this bit to shatter when a side load
was put on it, but to my amazement, it kept on trucking, major bonus
points here…all things considered, these bits are extremley
forgiving.

With the point geometry, the cutting action is more akin to muscling
thru the stainless, especially at slow rpms, without a spiral flute,
chip extraction is almost non-existant, so peck drilling is
advantageous with this bit to clear out the chips created. Lastly,
the point geometry doesnt grab the material like spiral flutes tend
to do, its more of a scraping action that achieves the cut, this
bit WILL CUT through work hardened stainless as well. I run these at
a medium rpm with my fordom and the chips are tiny flecks, not spiral
strings most people are used to.

Now the disadvantages of these bits…they are pricy…starting
at $10 USD each, a hand full will run you a small fortune, I dont
recomend free hand drilling at high speeds with these either, you can
generate enough heat to break down the carbide, causing them to dull.
If your needing smaller sizes (pg. 119 of the big book), MA Ford
makes the same thing with a 135* point down to #68 (0.031"), but
these start at $17 USD each.

Sorry to say this isnt the least costly solution, but it is a great
solution none the less, and I work with stainless all day, the
upfront cost is scary, but the long term payback is well worth it. Id
imagine using these bits on softer metals, they would last a
lifetime.

Good Luck,
P@
www.patpruitt.com


#8

Hi, Holly

Sorry to hear you have been struggling with stainless. I really hate
working in it and avoid it if I can.

My husband has a small machine shop and while he doesn’t love
stainless either, he does work in it and had the following
suggestions (in addition to James Binnion’s recommendations) :

Don’t centerpunch unless you really need to. If you do, use a narrow
punch like an ice pick rather than a broad punch that is more the
shape of the tip of the drill bit. This will help prevent work
hardening the area being drilled.

Use a good cutting oil as a lubricant. Not all lubricants are good
for all jobs. He recommended 'Tapmatic Gold" Cutting Fluid or another
cutting oil. Don’t use a light oil such as sewing machine oil and
don’t use WD-40.

He echoed the same already given about drill bits and
drilling.

Good luck to you.
Deb Jemmott


#9

What if the mystery is a super alloy? I still have a score to settle
with a piece of Inconel 718 that walked my end mill around the piece
without really doing a good job of cutting.

A new HSS drill, lubricant, and pecking should have no issues with
stainless steel. Keep the heat off the drill, and it will stay sharp
longer. Use a center punch followed by a center drill if you have
trouble keeping the drill on the mark.

Jeff


#10

Hi,

I still swear by cobalt bits. Start with a small one then open up the
whole with a larger bit. My local store carries them for.40 each. As
for centering skip the punch all together as it adds to hardening the
metal, instead use a diamond bit bur to get a divot started, I prefer
to use the ball shaped one, can be bought cheaply in sets of 12 - 18
for 2-3 dollars. They are not quite precisions tools but get the job
done for a good price.

Christine


#11
I still swear by cobalt bits. Start with a small one then open up
the whole with a larger bit. My local store carries them for.40
each. As for centering skip the punch all together as it adds to
hardening the metal, instead use a diamond bit bur to get a divot
started, I prefer to use the ball shaped one, can be bought cheaply
in sets of 12 - 18 for 2-3 dollars. They are not quite precisions
tools but get the job done for a good price. 

You are quite right about “cobalt” bits, they are good drill bits,
they are still high speed steel however. High speed steel (HSS or
HS) is a family name for tool steel alloys that contain iron and
carbon and then one or more of the following alloy additions:
tungsten, molybdenum, chromium, vanadium, manganese and cobalt.
“Cobalt” tools are a formulation that includes 4-10 % cobalt and as a
marketing convention are sold as “cobalt” or High Speed Steel -
Cobalt they are in all likelihood M42 tool steel which is the most
common form of “cobalt” tool steel. M42 is better at resisting high
temperatures, is less likely to chip and has higher wear resistance
than other common high speed steels which is why it is preferred for
tough to cut alloys like stainless.

James Binnion
James Binnion Metal Arts


#12

Hi Folks…

You are quite right about "cobalt" bits, they are good drill bits,
they are still high speed steel however. High speed steel (HSS or
HS) is a family name for tool steel alloys that contain iron and
carbon and then one or more of the following alloy additions:
tungsten, molybdenum, chromium, vanadium, manganese and cobalt.
"Cobalt" tools are a formulation that includes 4-10 % cobalt and
as a marketing convention are sold as "cobalt" or High Speed Steel
- Cobalt they are in all likelihood M42 tool steel which is the
most common form of "cobalt" tool steel. M42 is better at resisting
high temperatures, is less likely to chip and has higher wear
resistance than other common high speed steels which is why it is
preferred for tough to cut alloys like stainless. 

Generally speaking, in the Industrial world…If your dealing with
stainless, the cobalt drills Jim mentions are the choice…The heavy
duty grind on the drill is 135 degrees, most often split
point—reduces wandering when starting…

A lot of mfr’s use the shorter or stubby drills to reduce
flex…it’s more rigid…as long as the application allows it…

One of my best customers was GE Med Systems (GE Health Care) plant
in South Milwaukee…the maintenance dept… In this plant, there
was
stainless all over the place…corrosion issues and a lot of vacuum
system stuff… The application scenario was most often not
production…

For “the boys” the drill of choice was TIN (titanium nitride) coated
cobalt drills…The coating adds to the heat and wear resistance of
the tool, because of the increased surface hardness…Rc80 or some
ridculouly high value, but you don’t have a brittleness issue
because of the cobalt steel substrate…

You can’t mistake them…they look like they’re gold plated… You
can get TIN coated for both high speed and cobalt drills…It helps
performance for both…

But for stainless stuff “the boys” swore by (not at) TIN coat
cobalt…

The other thing was…they have a lotta SA…You open up a set of
those, and it looks like jewelry…

They’re a bit pricier than standard cobalt, but less than
carbide… People who use them insist they’re worth every penny…

The only down side, was you can’t use them for titanium
alloys…and that’s because the TIN coat reacts with titanium…

Hope this helps…

Gary W. Bourbonais
L’Hermite Aromatique
A.J.P. (GIA)


#13
M42 is better at resisting high temperatures, is less likely to
chip and has higher wear resistance than other common high speed
steels which is why it is preferred for tough to cut alloys like
stainless. 

I’ve been following the discussion of appropriate drill bits for
stainless steel with interest. But I work in copper. 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. 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.

Sandra Graves


#14
The last run I did ended up with dull bits after every 20 holes. 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 would sharpen them with a seperating disc. just takes a minute.

Bruce Holmgrain
JACMBJ


#15
I've been following the discussion of appropriate drill bits for
stainless steel with interest. But I work in copper. I've been
going through drill bits like water - they lose their bite so
quickly. 

I was following the topic as well, but decided not to participate
because very little made sense to me. 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. Center punch your
holes, using metal plate under it and your drill should retain edge
longer.

Another one that made me chuckle is applying pressure to a drill.
There is a huge difference in using drill press and drilling by hand.
Twist drill by their geometry feed themselves. In drill press, this
phenomena is not present because drill is secured and part is
secured. You do have to apply pressure to make a progress. In hand
drilling it is different. The reason for drill breakage is due to
design, drill bites more than it can chew. It causes edge wear and
breakage. This is primary reason why jewelers using what is knows as
flat drills. There was a good recommendation of using flute drills,
but they are expensive and not available in enough sizes. If limited
to twist drills, the pressure is applied to the bench pin via pinky,
(not to the drill itself) to counter the drill property to chew on
too much metal. Counter- punching helps as well. It is easier to
drill work-hardened metal than annealed.

The best practice is to always counter-punch; then drill with 0.5 mm
drill; after that enlarge to almost the size with jeweler’s saw; and
then ream to the required size.

Leonid Surpin
www.studioarete.com


#16

Bruce - you mentioned sharpening drill bits with a separating disc.

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.

Thanks,
margaret


#17
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. 

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.

Dremels and foredoms dont get high enough RPM’s to drill efficiently
with that size of bit. Alternatively, you can get a speed-increasing
handpiece for your foredom (No. 35 handpiece), the disadvantage of
this hand piece is you have to find 1/8 or 3/32 shank bits.

Lastly use a cutting lubricant, not water, my guess your getting the
cutting edge too hot and its loosing its edge.

P@
www.patpruitt.com


#18

Thank you ALL so much for your advise and taking the time to reply.
I am impatiently awaiting my HSS bits. I could not find titanium
which was my first choice - Rio didn’t have them anyway. I find this
list to be very knowledgeable and I knew I’d get lots of great
responses.

Wish me success!
Holly Gage


#19

The most obvious improvement would be to use a drill press; the next
would be to have a backing material. And why are you drilling under
water?

KPK


#20

margaret, my method is to load a separating disc into flex
handpiece, hold the handpiece in an upright position, and touch one
of the front angles of the drill with the flat sides of disc, the
underside in this case, not the edge of the disc, mimicking exactly
the original surface of the drill, works best if you color the 2
surfaces with red sharpie, then do the other side, only the drill
tip, drills are not sharpened along the outside length, must be
done very lightly, so as to not grind much of the drill at all, just
enough to take away the red, also best if done with one swipe, and
of course make sure that you have touched the cutting edges, red
off!!, practice!!, and a steady hand are important!!, one thing-
too many sharpenings, or passes on the tip will increase the web of
the drill, which can also be re-established with the edge of the
disc, that is another story, but can be done, or a center drill can
be used for those many times sharpened drills, in fact a center
drill is a great way to go for sturdiness, come in many small sizes
i don’t know how deep you are drilling, but important aspects are to
hold the drill very short in the chuck, buy a good quality small
drillpress, in fact only do it on a drillpress, milling machine or
lathe if possible, look into buying a “drill doctor” that sharpens
in that range, get a drill sharpening book or find it on the net,
get a drill tip gage, shows correct angles, don’t grind past the
center of the drill, sides must be equal, only the red,

dave