Cutting holes in stainless

[marshbrewer]

I need to cut some large holes in my thermopot to for the bottom drain. Smaller holes, for all the 1/2" stuff I've got covered by a qmax cutter.

So, what kind of holesaw blade do I need? Will a bi metal one be too soft; do I need some kind of carbide blade?

Do I need special drill bits to make the pilot holes for both?

Ta!

 

[Gerryjo]

Carbide cutter would be good but pricy though a Bi-metal cutter will do the job just be gentle with either copper grease or cutting compound and depends on how many holes and the type of stainless.
I've used Bi-metal to cut through H-beams.

 

[user 18729]

Cobalt bits for pilot holes, nothing else will bite into stainless

 

[marshbrewer]

Thanks both. Duly noted.

My greatest fear is contaminating the stainless, so it rusts. Is there any danger of that with a bi metal cutter?

I need to do 2 holes, both about 57mm.

 

[dcbrookes]

Cobalt bits for pilot holes, nothing else will bite into stainless

I've drilled many holes in stainless and have never owned a cobalt bit - a good sharp HSS one works perfectly!

 

[LeeH]

DIY HSS drills will soon dull, but a quality bit is perfectly fine. Drill slow with some sort of lubricant and coolant. WD40 will do if that’s all you have.
Same applies with hole saws.

 

[trummy]

Re Rust - Surely depends on the quality of the steel. My understanding is that it comes in different grades and the upper end should not rust. If there is no sign of it now then you should be ok

 

[user 18729]

I've drilled many holes in stainless and have never owned a cobalt bit - a good sharp HSS one works perfectly!

You’ve been far luckier than me then…

 

[starseeker]

A good trick is to stick a piece of masking tape where the hole needs to be ,mark that ,and then that will stop the drill bit wandering as you get it started .

 

[Festival Man]

Diamond whizzer grinder blade,/ diamond drills.

 

[sifty]

I used a stepped drill bit to enlarge the tap hole in my s/s fermenter. Worked well...

 

[YeastFace]

From memory, the thermopot skins are much thinner than the kettle wall, I used a bimetal holesaw for my bottom drain (the underside section). Just add cutting oil, go slow, apply pressure and you should be fine.

 

[marshbrewer]

Thanks for all the advice. Hopefully pick up a few bits and bobs this week, and give it a go at the weekend.

 

[scrap iron]

Bar keepers friend can be used to passivate stainless steel. I just used some recently on my keggle sparge tank after drilling for a thermometer. If it's not available in the UK it is Oxcalic Acid and Citric Acid. This is the liquid version.
This will keep it from rusting.