Cut holes in stainless??? Carbide hole saw?

[Jet-Stream]

From time to time I need to cut holes in stainless. Today it was a 7/8" hole in an electrical cabinet. Sometimes a hole for a fitting to weld on a water tank. etc. etc.

I have met with much frustration in my efforts. I have tried: --Large drill bits(working from small to large)$$$ --Bi metal hole saws. -- Plasma cutter (with template).

None of these methods work very well. The plasma cutter is the only thing that gets the job done. The hole saws burn up. large drill bits only work for 1 or 2 holes before dulling beyond usefulness (the large ones are very difficult to sharpen). And, the plasma cutter isn't very accurate.

I have considered investing in Tungsten Carbide hole saws. They are very expensive.

Anyone have any experience with carbide hole saws or have any other suggestions?

Thanks

 

[MEP001]

I've cut many thousands of holes in stainless with hand tools. I always start with a 1/8" hole with a cobalt bit and use a step-bit to enlarge it where I need it. Even the cheap step-bits from Harbor Freight last a long time, as long as you drill with a slow speed. I never use cutting oil with either the 1/8" bit or the step drill. For holes larger than 1" I use a knock-out punch - you only need to drill a 1/4" hole.

 

[Eric H]

Even the cheap step-bits from Harbor Freight last a long time, as long as you drill with a slow speed. I never use cutting oil with either the 1/8" bit or the step drill.

I was going to recommend the step drill too. I do use "Pro Tool Lube" http://www.toolbarn.com/lenox-68040.html
The slow speed is the key to not burning up the bits

 

[Earl Weiss]

I was going to recommend the step drill too. I do use "Pro Tool Lube" http://www.toolbarn.com/lenox-68040.html
The slow speed is the key to not burning up the bits

Yep, Slow Speed. Use Ridged Bi Metal Hole Saw from Home depot. May take 2-3 to get the job done. I lube / cool with WD 40

 

[Greg Pack]

I really like my lenox bi-metal hole saw kit, It is 10X better than the Milwaukee bi metal kit. But I cannot say that I have tried either on stainless.

So how thick of stainless will the knock out punch work on? This sounds like the ticket.

If the harbor freight works for just a couple of holes, that would also be good. You can get catch them on sale for very cheap. I have a lenox step kit that I love, but I try not to do much metal work anymore.

 

[CRHAMEL]

We work with S.S. every day...
Using a step drill is the best
Low RPM and dont be afraid of a lot of coolant
If you want to use a Plama torch that works VERY WELL. If you happen to have one laying around

 

[MEP001]

I really like my lenox bi-metal hole saw kit, It is 10X better than the Milwaukee bi metal kit. But I cannot say that I have tried either on stainless.

I have; it's not fun. It's really tough because the saw wants to bite into the stainless. You need a really strong drill with a low gear, and then it just grabs and snags and twists and cuts very slowly. If you try to go at it like you would with steel the teeth just melt; then you've just tempered the stainless and made it even harder to cut.

So how thick of stainless will the knock out punch work on?

I've punched 2 3/8" holes in 16 ga stainless with a standard Greenlee knockout punch. Grainger's site says it can do up to 10 ga mild steel. I don't think stainless is any harder, but it's more abrasive to cutters and will probably dull it quicker.

If the harbor freight works for just a couple of holes, that would also be good.

I bought the 3-piece set from Harbor Freight for $10. I've drilled dozens of holes in stainless with each one and they still cut well. They've held up better than the Leeson that are $70 each; at some point those will chip off at one step and stop cutting. The Unibit are worse because there's only one cutting edge.

 

[Reds]

Slow speed, heavy feed, dark cutting oil works for me. Stainless Steel "work hardens" - it gets harder as you work it, i.e. bang it, rub it with a dull drill bit, etc. Thats why the slow speed and heavy feed - you have to keep cutting because if you are not removing metal you are hardening it. I have used a Greenlee knock out punch on it too. It's always a challenge and once you harden it by using a dull bit you are in a jam.

 

[waright]

I saw a neat little trick by an electrician. He packed a small oil-soaked rag or paper towel inside of the hole saw before he started cutting. It really kept the right amount of oil on the teeth. I would recommend slow drilling with a hole saw.

A knockout is still the best way, unless it is thicker stainless.