How Do I Drill Stainless Steel?

[abrogard]

I am like totally ignorant. I hope that doesn't bar me from these informative forums.

I don't even know what 'CNC Machining' means and I only post in this forum because there was another thread in it about drilling stainless steel.

Unfortunately the answers that guy got are altogether too technical for me.

I need simple answers.

And I need to try and put my questions simply:

First: The job is simply to drill a hole in a stainless steel cleaver (About maybe 4mm thick) so's it can be hung up out of the way of the kids.

Second: I've made a start on it. I started with a normal drill and realised it wasn't getting anywhere after a while, went and got a couple of titanium coated bits and shopped further and got some 'panel drill' (whatever that means), double ended, cobalt coated.

I've even bought a 5 speed drill press (thought it was about time I had one).

Third: Where I'm at now and the puzzlements I'd like someone to please help me with:

The panel drills said 'don't quench in oil or water' - does that mean don't use oil as a lubricant during drilling. Or are they referring to dipping a red hot drill in a bath of it?

i.e., should I use oil or not?

Or should I use the 'cutting fluid' I read about in that other forum.

The bits seemed to get too hot too quick at the higher speed so I've moved the speed down to 800 and it seems to be happier there - but virtually getting nowhere.

Question: is this supposed to be a long, long, grinding away process or should I know something 's wrong if it's not done in a minute or two?

i.e. is that speed okay?
i.e. is an apparently 'going nowhere' cutting thing in the hole okay? Or should there be shavings?

I went back to the titanium bit because it is smaller diameter (I'm at about 2 or 3mm). And I ran it without any oil. It made enormous squealing and strange sounds and generated little particles of dust.

Is that 'squealing' a good sound or does it mean I've buggered the drill or something?

Are those little particles what we should look for to know stainless drilling is proceeding right?

Considering all of the above - smoking hot oil in the hole, oil in the hole, squealing, running at at about 1500 first, now grinding away for minutes (going nowhere) at 800 - what's the chances I've hardened the stainless and should just give up?

Can anyone please set this mug beginner right?

regards,

ab

 

[RAS]

You've work hardened that stainless. Not an insurmountable situation, but frustrating for a newbie, for sure. First question: what size hole are you drilling? A hanging hole is probably about 3/16"... Based on speeds for 300 series stainless, you should have been running around 1000 RPM (50 SFM). The thing with stainless is, you have to FEED the drill, don't baby it. Once a chip starts, keep it going. My guess is, that you let the drill bit dwell, and, boom, work hardening... Now, you have to break that skin. Try about 600 RPM, with cutting oil, and don't be shy with the FEED. Push the bit through that skin, and you'll have your hole.

RAS

 

[damonfg]

If this was hardedned stainless, now with a work hardened spot, it will take some effort to get back on track. carbide drill bits are recommended in this case. use cutting oil, and as RAS says, put some muscle into the drill press. Don't shatter the drill bit - but you will need to put a good load on it to get through the surface.

For a cleaver, I assume it's pretty thin, once the drill starts, stick with it until you are done.

If you want a bigger hole, use a bigger drill from the start or be sure to clamp it to the drill press before the first hole, and dont remove it until after the last hole is drilled.

 

[Bobw]

If its a cleaver, I'm going to guess that it is 440C, and hardened somewhere around a 60C, which is only a little softer than your drill bits are.

You are going to have a hard time without using a carbide drill. It probably can be done, but you will probably eat up the drills pretty quick.

Go as slow as you're drill press will allow, lube it up and lean on it, you should blast through in a couple of seconds.

 

[b&s man]

Do not hold in hand clamp it to the table or when the drill breaks thru you will have a spinning knife.

 

[currawong]

These will do the job.

http://robinsoninternational.com.au/cutting_tools/artu.html

 

[RAS]

Guys, I would guess that this cleaver is 304, with no hardening (Chinese knifeware). The only hard spot is probably where our friend tried to drill... A good HSS, or even a carbon steel drill bit will get through it, with a bit of effort.

RAS

 

[piniongear]

I do not see it suggested here anywhere, but perhaps I missed it.
To drill stainless he should use a cobalt bit, not a carbide. At least that is my practice which began the first time I tried to drill SS using a HHS bit.
I just bought myself a complete set of cobalt bits. Use them with oil and do not keep them burning against the stainless. Drill, back off to cool a second, drill again etc and keep the oil on the bit.I drill a lot of stainless steel by the way......pg

 

[RAS]

No offense, pg, but carbide is used extensively in production environments, to drill stainless. Also, HSS and carbon steel... it's just a matter of using the right feeds/speeds to get them to work.

RAS

 

[Greg White]

I do not think carbide is a good thing to use in a drill press unless one has considerable practice?my .03 cents.
gw

 

[abrogard]

Well thanks for the interest and the input, guys, it is obviously a question worth asking, the answer not being plain and simple, clear and obvious.

In fact I'm a little confused after all your help. Conflicting stories and no one seems to give the whole answer - oil or not, kind of oil, drill speed, continuous or intermittent drilling, kind of bit to use.

I'll go buy some cutting oil and talk to the guys down there and see what they've got to say. Then I'll come back and try again with my 'panel' cobalt bits and the cutting oil and I'll put my gloves on and eyeprotectors and I'll really lean on it and I'll try to do it bit by bit with a cold drill, stopping to let it cool. Like piniongear says, he says he drills a lot of stainless.

And I figure if that's the wrong way at least I haven't case hardened the thing any more so it'll be good - or as good as it was - to retry some other way....

wish me luck...

I'll report what happens...

ab

 

[abrogard]

Well I didn't do what I said I would - there was no cutting oil down there so I've had to wait a day until they get some in ( in a tube, they say ) and meantime I ran out of patience and had a go.

I used 500rpm and ordinary engine oil and the 'panel' cobalt bits. I leaned on it until it began to smoke and then I backed off, right off, and let it cool.

I had four of those bits - two double ended bits - and they're all blunt now I think.

When I first started they would screech which made me think they must be cutting. When they stopped screeching I assumed they were blunted and just spinning on the metal, polishing it (and case hardening it?) so I stopped using that bit and switched.

Now they're all blunt. How do you know when a drill is blunt? Seems to me they've got a flat land worn onto the outside of the cutting edge, where it meets the metal, and they seem to have a lip developed on the inside (within the flute) of the cutting edge - is that right?

And how do you sharpen a drill?

Is it possible for a newbie like me to be taught via the web what it took trade school, guidance, tutors and experience for you guys to learn? i.e. sharpening tools?

I hope it is.

I will google around and see if I can find some clues.


The hole, by the way, is deeper and wider and, yes, it's about 3/32".

My wife is very impressed by the failure to drill a hole. She thinks it is proof that it is a wonderfully hard cleaver and she's proud of it.

 

[spindlestop]

abrogard, You must be the most patient and perservering man in Australia. I would probably have took a acetalene torch and blowed a hole through it then cleaned it up with a sanding wheel. not pretty but, JOB DONE. john

 

[kustomizer]

perhaps too expensive for this project, but every shop should have a set of these drills. They will drill a hole in a good file, or just about anything else and they do fix or repair free. www.baddogtools.com

 

[baldhead]

If you have a dremel tool you could try and use a small stone to grind a hole.. You could buy a small stone and try and chuck it in your drill but I dont think you will get enough rpm..

 

[abrogard]

If I had a torch I'd probably have done just that.

The Baddog drillbits look good. I don't know that I can get them here.

I've never heard of dremel tools before. I googled it and I see they're high speed drills beginning at about 3000rpm. My drillpress peaks at 2500 I think. What my hand drill does I don't know. I've never heard this suggestion before, either, grinding the hole...

I'm interested that the baddog tools suggest running at 2500rpm on stainless. That's with their bits, of course.

I googled the whole thing and got a good page that listed drills in order of hardness and went past two kinds with just a numbers for names and then finished up at carbide.

Seems to me carbide is the way to go. Invest in a carbide drill and get it done. Then you've got that drill sitting in your collection for next time, if one's ever driven to doing it again.

But I wonder about the warning expressed by Greg White. What's the danger here?

p.s. I note the diamond member said right at the beginning 'use carbide' and, having spoken, moved on....

 

[bradleyk]

The danger with carbide is it can shatter at worst...but most likely will just chip out or break. Carbide has excellent wear resistance but chips easily...is brittle.
I don't want to put words in Greg's mouth but this is probably what he was referring to. Putting this kind of tool in an open drill press without any experience and feeding by hand may not be good.

Over 70% of the metal I work with is SS and is considered our 'easier stuff to work with'. HSS and cobalt work fine but I prefer carbide for production reasons.

The baddog drill looks interesting...never heard of it before. Just from what I read it looks like that may be your best option at this point since your cleaver is likely work hardened and the fact you are using a drill press.

If you continue with HSS or cobalt bits use this formula for your speed calculation:
SFM/.262/Drill diameter

SFM (surface feet per minute) for HSS is 45-50
Coablt 55-60
Carbide about 150
These are ballpark numbers not meant to start debate on feeds/speeds of SS.

 

[Greg White]

I do not think you can learn to sharpen drills on the net,not from me anyway,.a good film or some good pictures would help,I have my shop class books from high school,class of "69" that have some excellent pictures.
Brad,thank you for adding to my comments,chips are my fortae,not words,all to often a mans problem or questions becomes a pissing contest between the observers,at times I find it funny,other times annoying.
Sreeching does not sound good at all!You need to rub elbows with a machinist or tool and diemaker,proper cutting oil is needed,now i m lost for words,can't see your drill!!!!
Brad perhaps you could do the s.f.conversion for this gentel man,and give him a rpm ballpark.
interesting project here,trying to drill a hole with words.
GW

 

[CPT Crunch]

Just make sure you clamp the cleaver down. I just had a vision of the drill "catching" as it breaks through the bottom side and becoming a motorized meat slicer. Not pretty.

 

[steamhd]

Get a carbide drill and bolt the clever down to the drill press table and turn your rpms down oil won't hurt.
Kevin