Drilling into stainless with a bit that is not stainless

[J187]

I heard somewhere - I think brewstrong perhaps - that you cannot drill through stainless without using a stainless steel bit or the metals will react and oxidize (battery). Is this a common problem or do you guys drill with carbide or hardened bits? I'm not feeling the $70 for a SS step bit.

 

[Stealthcruiser]

Slow speed, heavy feed, and use some cutting lube......NOT WD-40.
Many stainless projects done here with the Habor Freight variety pack of "step drills".

 

[J187]

Thanks. I was mostly worried about the metal reaction I heard about, but if most people aren't having problems... I"ll the harbor freight thing - actually, I think I have a carbide step...

 

[Monster Mash]

Thanks. I was mostly worried about the metal reaction I heard about, but if most people aren't having problems... I"ll the harbor freight thing - actually, I think I have a carbide step...

A carbide step bit works well, just remember to drill slow and keep it cool. I have found that running cool water over the area as you cut works well because as long as the stainless stays cool it won't harden.

I have drilled over 20 holes with my step bit while doing this and it still cuts as good as it did when new.

 

[DaleHair]

I understand the concern about contaminating the SS with carbon, but drilling with a carbon bit does not seem to be a problem. Maybe put some sand paper to the cut to remove any carbon.

 

[jigtwins]

Stainless steel contains carbon and iron . so no worries about drilling. The chromium gives it certain corrosion resistant properties.

 

[outside92129]

Contrary to what many people think stainless isn't that hard of a metal. It's so soft that you wouldn't want to make a drill bit out of it. A metal shop would use a cobalt bit on stainless, many folks use titanium, and high speed steel (HSS) will work fine (just not nearly as long as Ti or Co).

The "battery effect" won't be a problem if you're just working the metal, it's more of long term issue with dissimilar metals in a corrosive environment.
http://en.wikipedia.org/wiki/Galvanic_corrosion

However of greater concern is contaminating the stainless with steel, though it's generally not a problem with drilling, especially if you sand/file down the area. The tool here is much harder than the stainless and any particles that do wear off are removed. This is a serious concern when sanding/brushing with contaminated pads. If you take a wirewheel that was previous used on steel (or if the wheel is made of steel) little particles of steel will embed themselves in the stainless and rust. A buddy of mine did that and wondered why his shiny new stainless parts were rusting! (he didn't get it hot to cause the chromium to come out of the metal - an issue when welding)

 

[SobchakSecurity]

http://www.amazon.com/gp/product/B002BAZWF0/?tag=skimlinks_replacement-20

I'm a big fan of hole cutters like the above. Cuts a perfect 7/8" (1/2" clearance) hole, leaves minimal burrs, and as long as you take your time, and set the clutch whilst drilling the pilot, they'll last for many holes, even in stainless.
-Dude

 

[Bookworm]

Cobalt is very nice, if you have the money. The down side is the good ones a very hard and that correlates to very brittle. They are not hard to chip and it will ruin your day if it is a large expensive cobalt bit.

Personally I am not sold on most of the titanium bits. It is generally just a thin coating over high speed steel and I do not think it gives much of an advantage.

 

[dmwahl]

I'll add some experience here as I've drilled a bunch of holes into stainless recently. Mostly brew pots (~1mm) but also a few pieces ~10mm thick.

1) Good sharp bits are vital, regardless of whether they're HSS, cobalt, etc. A sharp HSS bit will beat a dull cobalt, carbide, etc bit.
2) Go slow. Stainless work hardens, and you don't want to heat it up. I find that using a battery powered drill and pulsing the trigger for as short of a burst as I can works well.
3) Use lubrication. I use vegetable oil as it's something that I have on hand and don't mind a drop or two of in my kettles. Plus it smokes at a relatively low temperature, so I know if I'm risking heating up the metal too much.

 

[kristiismean]

2nd the vegetable oil. it's not a great high temp lubricant, but if you are going slow, then it should do the trick (it's what I use)

any food safe lubricant will work (like vegetable, canola, peanut, lard, brocolli).

Depends on the pot. Thin ones like Bayou classic do not need a knockout punch. use a step but, don't even need lubrication.

But any thicker then yes, use lots of lubrication and go slow. if it's having trouble cutting, stop. don't try to force it.

 

[texasbrewer73]

Bobby M has a Tungsten Carbide bit as well at a reasonable price. Takes about 30 seconds per hole, including drilling the pilot. Strongly suggest using cutting fluid.

I needed to drill 9 holes in my new set up and 1 bit got me through 6 and half holes. If you have a lot to drill, I'd suggest getting two bits.

https://www.brewhardware.com/product_p/holesaw21.htm

 

[patthebrewer]

Count me in as one of those guys who took a harbor freight step drill bit to my all my ss brew vessels ( brew kettle, HLT and Fermenter) Last one I did was in 2010, still no issues

 

[Morrey]

+2 for HF step bits. With a 20% coupon, it cost me more in gas to go 10 miles to pick them up than I paid for the 2 pk bits.

 

[MatterOne]

A metal shop would use a cobalt bit on stainless, many folks use titanium, and high speed steel (HSS) will work fine (just not nearly as long as Ti or Co).

Not necessarily. For low quantities, a shop might use HSS (most likely TiN coated), although they would also (where possible) be using flood coolant.

And for high quantities and deeper holes, they'd likely use carbide.

Cobalt is very nice, if you have the money. The down side is the good ones a very hard and that correlates to very brittle. They are not hard to chip and it will ruin your day if it is a large expensive cobalt bit.

Personally I am not sold on most of the titanium bits. It is generally just a thin coating over high speed steel and I do not think it gives much of an advantage.

If a cobalt drill chips, it can be touched up on a standard aluminum oxide grinding wheel, just like a HSS drill can.

Yes, "titanium bits" are not made of titanium. TiN (titanium nitride) is a coating that's applied to cutting tools (HSS, cobalt, carbide, etc.) to increase life (by more than double, in many cases) due to it's hardness and low friction coefficient. However, all TiN coating is not created equal. Harbor Freight will sell you a low-quality drill with a low-quality TiN coating. And if that works for your application, then you get to enjoy their low prices.