# Drill recommendation for drilling stainless steel?



## purple-lazy (29/6/15)

I had a bit of a disaster yesterday trying to drill pilot holes in my stainless steel pots. After a bit of a false start with bits that weren't up to the job, I got a 3mm cobalt bit and made some progress. However I was still having to use a *lot* of down force to get anywhere. Which meant on the second hole I snapped the bit and crashed the drill head into the curved base of the pot, which was no where near as impervious as the rest of the pot. I don't know if I hit a weld or a weak spot but I cracked it with unbelievable ease compared to all my previous efforts.

I think my problem was the drill I was using, it's a corded Bosch which is listed as having up to 32NM of torque in low gear. Apparently cordless drills typically have a lot more torque than the corded drills at low speed. Can anyone recommend what I need to be looking for to get the job done? Do I want a cordless drill? How much torque should I need?


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## seamad (29/6/15)

You want torque, but slow speed and use some lube (even wd40 will do )


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## nosco (29/6/15)

Ive done a few holes with a cordless and a tungsten hole saw and had no troubles.

You might already know but from what i heard if SS gets too hot it hardens. So the trick is to use plenty of cutting oil, wd40 or whatever. As soon as it starts smoking stop and let it cool.


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## MitchD (29/6/15)

Torque isn't the problem unless the drill is stalling. What you need is practice on a sacrificial piece of stainles,. I drill stainless at work nearly everyday and there is nothing to fear about it if you know what to do.

Down force isn't a bad thing but you need to find a balance between pressure and cutting speed. I suspect you were also going full speed, that is a problem as SS work hardens so before you know it your drill bit is over heating and you are applying more pressure, on and on until it snaps.

Low speed, cutting fluid and patience are the key.


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## Danscraftbeer (29/6/15)

As mentioned the slower the better with cutting oil too (really slow!) You'd be amazed it goes through stainless like butter at the right speed without blunting bits. Faster just blunts the bit almost instantly. Even cheap drill bits can do the job if their sharp. Actually had a mate spray a tiny bit of water on the bit while drilling worked well too. Being able to sharpen your own bits is handy practice too.
Oh the joys. I know what you've been through...


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## purple-lazy (29/6/15)

Hey guys. Thanks for the replies. I was going slow (I think) and using oil (just plain old olive oil) and spritzing WD40 on the bit to try and keep it cool. I didn't see any smoke, but I just wasn't making much of an impact on the stainless. Very little indication of progress (splinters) unless I was putting my full weight on the drill. 

As this was my fist attempt drilling stainless I wasn't sure what to feel for, but luckily now I have a pot that I can practice on as much as I like.

I'll get some proper cutting fluid and give it another go. I'll probably try to borrow a different drill for comparison. What size bit should I use for the pilot hole? Is 3mm okay or should I go with something a bit sturdier, say 4mm?


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## antiphile (29/6/15)

I certainly don't have much experience (and even less skill) in drilling SS, so I certainly don't want to argue with these guys that really do know what they are talking about. When I did mine, I used an Ozito low speed, high torque corded drill that I primarily bought for using with the grain mill, but it really made the drilling very easy. IIRC, it has a max speed of 400 rpm, rated at 1050 watts, and was $95 or similar at Bunnings. Perhaps if you intend to use a drill with your grain mill, you could justify getting one.


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## purple-lazy (29/6/15)

Ha. Awesome antiphile. So you're saying if I get a cordless drill I'd almost be obliged to get a grain mill too! Win-win.

Seriously though thanks for the reference point. Good to know.


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## Danscraftbeer (29/6/15)

When you get the right speed with any size drill bit you get this without much pressure.
I think the hardest thing is getting a drill that has such slow speeds as an option.


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## Ducatiboy stu (29/6/15)

Nothing wrong with using vegetable oils at all

Even this stuff has it in it


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## Ducatiboy stu (29/6/15)

Danscraftbeer said:


> When you get the right speed with any size drill bit you get this without much pressure.
> I think the hardest thing is getting a drill that has such slow speeds as an option.


Fwoar....thats some sexy swarf B)


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## purple-lazy (29/6/15)

Cheers Dan. I definitely wasn't seeing anything like that with intact spirals. Just the smallest splinter fragments, and even then only when I was using a lot of down force.


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## purple-lazy (29/6/15)

Ha. Okay I have to admit that I just googled Swarf. I was slightly worried what hits I was going to get here at work.

Roger on the oil recommendation Stu, but I think I need every advantage I can get at this point. Does cutting oil have any "magical" properties?


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## Ducatiboy stu (29/6/15)

purple-lazy said:


> Ha. Okay I have to admit that I just googled Swarf. I was slightly worried what hits I was going to get here at work.
> 
> Roger on the oil recommendation Stu, but I think I need every advantage I can get at this point. Does cutting oil have any "magical" properties?


The idea of cutting oil is to keep the work piece and drill bill cool and lubricated. There is nothing "magical" about it. You can anything from kero/diesel to axle grease....vegetable cutting oils are pretty common


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## purple-lazy (29/6/15)

Roger regarding the cutting oil. One thing I noticed about the olive oil was that being quite runny for lack of a better term, it was difficult to keep a good volume of it in the right place, especially on the curved surface of the pot. Something a bit more viscous would probably be advantageous.


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## Danscraftbeer (29/6/15)

Ducatiboy stu said:


> Fwoar....thats some sexy swarf B)





purple-lazy said:


> Ha. Okay I have to admit that I just googled Swarf. I was slightly worried what hits I was going to get here at work.


I've read the rules.
Stainless Steel porn is fine.


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## neo__04 (29/6/15)

I had similar dramas early on drilling stainless.

I ended up getting a 3mm (approx cant exactly remember) drill bit from bunnings for stainless steel.
In a 18v cordless milwaukee drill. Drilling really slow, no oil. Worked a treat. (oil is recommended)

The thing i found was to just have a resonable amount of pressure, and go slow, like a revolution or two of the drill head every second and with enough pressure it just chewed its way through.

I avoided going to small with the drill bit so the pressure didnt snap them. Then used Step drill bits to open it up to a suitable size for a ball valve


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## purple-lazy (29/6/15)

Cheers Neo. Given that input I probably was going too fast. When I try again I'll aim for much slower. Not sure I could reliably keep that speed constant with my drill however. I'll practise a bit and see how I go.


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## rude (29/6/15)

I like kero in a spray bottle for lube on stainless
Dont breath in the treflux smoke though


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## superstock (29/6/15)

Ducatiboy stu said:


> Nothing wrong with using vegetable oils at all
> 
> Even this stuff has it in it


One of the best cutting pastes for SS and chrome moly


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## superstock (29/6/15)

purple-lazy said:


> Roger regarding the cutting oil. One thing I noticed about the olive oil was that being quite runny for lack of a better term, it was difficult to keep a good volume of it in the right place, especially on the curved surface of the pot. Something a bit more viscous would probably be advantageous.


Try the Trefolex. It's a paste.


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## Ducatiboy stu (29/6/15)

A tin of trefolex would last the average person about 200yrs


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## antiphile (29/6/15)

I've never tried it, and I'm one of those idiots who'd happily go to buy a skyhook or a can of striped paint on request, but I was once told drops of dishwashing detergent can be used as a lubricant for drilling metal too. But that could be because I don't only look stupid.


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## Ducatiboy stu (29/6/15)

Dishwashing liqiud works.

I know this from experience B)


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## MitchD (29/6/15)

Ducatiboy stu said:


> A tin of trefolex would last the average person about 200yrs


Or a person working in the lift industry about 6 months. We use the 3.2mm double end drills and they are light years ahead of the Sutton blue bullet. I think its to do with the angle the tip was cut at.


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## husky (29/6/15)

For me the formula is:
Cobalt drill bit. Non negotiable
Cutting compound. If its a big hole or a ole saw add some as you're drilling as well
Low speed setting on the drill
Once you start a hole don't stop. Stainless steel hardens if you heat it so get it done in one go. Any second attempt will be more difficult.


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## rude (29/6/15)

Apparently trefolex when the fumes are inhaled is carcinogenic excuse the spelling
On its own its ok & you don't wont to make it smoke for ss it would be getting too hot then
Just thought I'de let people know


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## Fylp (29/6/15)

I start with a punch to mark the spot, then hit it with a cheapie eBay hole saw made for SS. A friend of a friend is a metal worker and said to stop when you see smoke and hit it with more oil. The fella at LHBS says the guy who does theirs uses a regular hole saw and just takes it slow. 

Good luck


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## Danscraftbeer (29/6/15)

Can always widen and finish the hole with a dremil. But then you need a dremil ha


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## booargy (29/6/15)

Put the hose on it. Most of the time if you see smoke the bit is roo ted.
This was drilled with no cutting compound on a pedestal drill.


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## Camo6 (29/6/15)

And for drilling curved surfaces without the aid of a cutting compound paste you could always make a well around the area with blutak to hold oil or similar.


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## welly2 (29/6/15)

I've had to drill a couple of holes and I've got to say, either my drilling technique is crap (most likely) or something else but it's been serious work to get even a starting hole through the bloody things. Once I've got that done, the step bit has been fine but just getting that initial hole, even with a cobalt bit, has been a massive pain in the hole.


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## purple-lazy (29/6/15)

Thanks for all the feedback and advice guys. There's been some great stuff here, and I'm taking note of it all. Hopefully it'll make the difference.


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## Benn (29/6/15)

Water + dishwashing liquid +2 Stroke oil (probly any oil will be fine) ...or just pop down to the shops if they're close handy and pick up some cutting compound as mentioned above.


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