# Drilling stainless steel?



## GrahamRounce (11 Sep 2020)

Hi - I have a circular tray, 39cm across, shiny, which I take to be of stainless steel. 
It "donnnnng!"s very nicely, presumably because it's hard, and I'm using it to make a doorbell gong. (It was only£1!) I had it suspended on thin nylon (?) thread via tiny hookeyes epoxied to the back at the top.
All very well and good, but in the recent warm weather the eyes popped off. No problem, I thought, I'll just drill a couple of small holes near the top instead.
Unfortunately.... none of my drill bits would touch it. Nor would any of my cheap set of diamond-coated bits in a Dremel. I've made holes easily in a lathe chisel before now, so I'm a bit flummoxed.
Any ideas, please?


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## Rorschach (11 Sep 2020)

If it's thin enough punch the hole instead.


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## porker (11 Sep 2020)

I've machined SS often enough. Some of the grades can be very tough. Most of what I have done has been on a lathe or mill. My tips are
- Use a cobalt drill
- Use the right speed. A lot of people go full speed on a cordless drill and this is often too fast for SS (and other steels)
- Maintain sufficient pressure when cutting - once you let the drill slip, SS work hardens quickly and becomes very difficult to drill
- Use a cutting fluid (I use trefolex but other oils etc can be used)


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## hawkeyefxr (11 Sep 2020)

You will need a decent drill bit, most of the sets we buy are ok for mild steel some stainless is really gritty to drill. Get a decent drill bit and it will work well. My set of six drill bits were £20.00
Stainless comes in different grades, good stainless is not magnetic.


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## AES (11 Sep 2020)

Agree with all the above. Would add (again!) especially for emphasis:

1. GOOD quality drill (GOOD HSS brand will do - sometimes) but cobalt better. Not cheap, but you really only need a one off (IF you can find it, not a set. Try the internet):

2. LOW speed (if using a hand-held electric drill go to slow speed) but pillar drill better;

3. Keep "feed" (downwards force) quite heavy and CONSTANT - do NOT relax, especially if using a hand-held drill;

4. Use plenty of lub - ordinary "3 in 1" will do, but a special tapping/drilling compound is better.

You'll get there in the end - promise. Probably, especially if hand-held drilling, you have accidentally reduced feed pressure, so allowing the job to work harden and/or the drill to overheat & soften - likely both!

Edit for P.S. Rorschach is right, a punch will do - IF the hole/s is/are small, IF the punch is a good quality HARD punch; and IF you support the item on a suitable "former" (to reduce distortion) - e.g. a piece of softwood but with a suitable size hole/s in it.


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## sunnybob (11 Sep 2020)

most punches will blunt instantly on stainless.
Mostly as above but I would say MEDIUM pressure, not heavy. Dont force the drill through, it has to cut..
Of course, the thing is, if you have already tried and failed, that section of the stainless is work hardened and even superman couldnt puncture it. Move to a new unhardened area, slow speed, medium pressure does the business.


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## Rorschach (11 Sep 2020)

sunnybob said:


> most punches will blunt instantly on stainless.
> Mostly as above but I would say MEDIUM pressure, not heavy. Dont force the drill through, it has to cut..
> Of course, the thing is, if you have already tried and failed, that section of the stainless is work hardened and even superman couldnt puncture it. Move to a new unhardened area, slow speed, medium pressure does the business.



I was going to suggest a nail, preferably a hardened concrete nail but a screw would work as well.


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## sunnybob (11 Sep 2020)

I sincerely hope anyone who tried to hammer a wood screw through stainless steel took out health insurance before donning a haz mat suit.


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## AES (11 Sep 2020)

@sunnybob: I did write "QUITE heavy"! It's a question of using words to describe a force, and I don't fundamentally disagree with you by any means Bob. It's clear it's NOT a "light" force we're looking for here, and it's now up to the OP to make what he can of the terms "MEDIUM" and "QUITE HEAVY"! I didn't mean just "HEAVY" though (hence my use of the word "quite") but as I'm sure you'll agree, it's largely a matter of "feel" gained from "experience by doing". For someone who hasn't done it before, like the OP apparently, he'll just have to try and make what he can out of the above words! NOT easy - but as I'm sure you'll agree, the most important thing is not to allow the drill to "drag aimlessly" just heating everything up and not doing any cutting, just making the work piece MUCH harder/tougher.

Re punches, a lot depends on the thickness of the SS, and it's exact alloy (the "better"/"tougher" SS alloys are usually non-magnet - NOT always though, just to help the OP!); plus of course the size of the hole and the hardness of the punch. 

On thin SS I would certainly have no qualms about using one of those hardened steel picture hanging pins (they're usually a slightly blue colour) and in fact have just recently punched a hole in each of 2 pieces of SS (no idea what spec) of about 1 mm thickness using exactly that "tool". (I did just touch the tip of the nail on the off-hand grinder first though).

Just FYI, the job was 2 x SS chefs' funnels that I bought in the cookware dept of my local food supermarket. The aim was to reproduce the 2 big headlamps of the 1948 MG TC Midget "model" kids' pedal car that I'm (still!) building and was half way through writing up here a while back.

Job went like a charm BTW, but I DID use a pair of safety specs, (along with the slightly bluntened tip of the nail!).

P.S. I also agree with you Bob that the OP should NOT now try and make a hole exactly at/close to where he's already tried!!!!!!


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## Rorschach (11 Sep 2020)

sunnybob said:


> I sincerely hope anyone who tried to hammer a wood screw through stainless steel took out health insurance before donning a haz mat suit.



It's just to make the initial hole, once you have pierced it then it's easy to open it up with something else like an Awl. I have done this many times before when making camp cooking pots.


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## sunnybob (11 Sep 2020)

I usually describe pressure applied as "finger tight, wrist tight, elbow tight, and arm tight". After that its ARNIE tight.  
All descriptions of downward pressure are totally dependant on the person doing the work of course,


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## TFrench (11 Sep 2020)

In my day job I drill thousands of holes in 0.5mm stainless by hand for pop rivets. A decent drill bit (we use RECA) and constant pressure is the key. On very thin stuff like that cutting oil isn't really needed. How thick is your "gong"?


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## Robbo3 (12 Sep 2020)

I've drill a few hundreds of 8.5mm holes in stainless steel with standard HSS bits.
Centre punch, pilot hole & as already stated, firm pressure.
Both drills lasted about 80 - 100 holes. The old timer who showed me how to sharpen them by hand refused to do the smaller bits because they were so cheap & considered it a waste of his time.


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## MikeG. (12 Sep 2020)

I hope it's obvious that when drilling any sheet metal on a pillar drill, the work should be suitably restrained, not hand-held. My worst ever workshop injury was done drilling a quick hole in a bracket-shaped piece of steel, which of course grabbed, and flicked around with the drill. Clamp it down!!


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## GrahamRounce (12 Sep 2020)

Ok! Thanks for all ths help! The thickness is probably 1mm or less. It's hard to measure it because of the curved rim. It's definitely not at all magnetic.

The hole only wants to be maybe 2mm dia. Now I'm wondering if sharpening up a masonry nail and giving it a good whack might do it. Trying to clamp some wood both sides to avoid it slipping would be safer!

I was going to ask what would be a good brand of drill bit, but that's been answered. Usually they just come out of a drawer and you don't really know what you're buying. Ok for wood, but if you do particularly want a good one....


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## GrahamRounce (12 Sep 2020)

Oh, I forgot - pillar drill, 500 rpm


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## GrahamRounce (20 Sep 2020)

So anyway. I tried drilling again, slowly with oil, but nothing. In the end I did sharpen a masonry nail and whack it. It was still reluctant!! I got it through in the end, with harder and harder hammer hits. Not a very clean hole, a bit dented around it, but at least it's done. I dunno what it's made of, but it's *very* hard!


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## AES (20 Sep 2020)

Glad you "got through it" in the end Graham. But you're right, it does sound as if your particular bit of SS is VERY hard. VERY surprised to hear that.

BTW, if the bottom side of the hole is "ragged", it should be easy to clean it up a bit. "Just get a bit of softwood into roughly the curvature of you gong and tap it with a hammer - or even with a flat ended punch and a hammer (especially if you've got 3 hands - otherwise a helper to hold the gong). Afterwards a final clean up with a fine "rat tail" (tapering round) file or swiss or warding file, whatever you have to hand.


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