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cutting stainless steel


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not sure if this is an appropriate place for this but hoping it falls under 'fabrication' and some folks here might be able to advise. I'm looking a good way to cut stainless steel (milk can) without work hardening it and cutting on a curved surface. I don't have access to a plasma cutter and not sure what the best approach might be. Hole drill on low speed? Step drill bit?  It's a $130 investment so I'm nervous about ruining it and don't want to experiment. I haven't worked SS before.

Thank you!

 

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All I know is stainless eats normal (even what I'd consider "better" bits) drill bits for breakfast. It laughs at average metal saws. 

For me it's cutoff wheels or plasma cutter. If it's worth the money, there has to be Someone around with a plasma cutter. Or buy the really good drill bits and follow best practices. 

Just one guys opinion. 

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Herr Das,

Has stated concerning cutting  and or drilling stainless by writing,

" ...  or buy the really good drill bits ..."

Are you referring to cobalt steel drill bits?

Hope to hear from you in due course.

SLAG.

 
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Slag, either cobalt or titanium drill bits as far as I know. Please research at your leisure as I am not an expert and have had ok and bad luck at drilling stainless with different cobalt or other bits. Found the higher quality to work and last better. I have read some into it but usually expect any bits I'd buy as expendable, but also have a few plasma cutters for more than one reason. I will say in this that brand and quality do matter as much as proper technique( or best practices) in using the bits. 

I do know that you cannot just beast through stainless with the wrong bits and bad technique, or one or the other. I've ruined more bits than I care to say on stainless. Sometimes one hole per bit. 

Funny, with the types of steel alloys used on cars anymore, some of our best spot weld cutting bits may last one weld or 20+. It just depends... I remember a honda pilot rear body and floor where the only thing that would cut the spot welds was using a quality 1/8" double ended bits we had then cobalt step bits.  Ate the expensive spot weld bits like they were nothing. 

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What happens most time when people try to drill Stainless (or any other kind of hard steel) is that they use the same drills as they do for softer steel, drill for softer steel usually have a tip angle of about 118°, for harder types of steel you really need a bigger cutting surface (else you are just going to burn the tip and the metal) so anything around 130° or 135° will be fine. If you want to use a hole drill your best bet are one like the "RS PRO Tungsten Carbide Tipped 32mm Hole Saw" those will eat trough hard steel like it is cardboard. Just go slow and listen to the drill, if it starts shouting at you, you are going to fast. As long as you hear it cutting and scraping away metal you are at a good speed. 

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White bi metal saw blades and use as slow a rotation speed as you can with hole saws. I have good luck with my Bowman, self starting, cobalt bits.

Stainless tends to be "chewy" and rolls the edge or HS drill bits and saw blades but if you have a good touch you can use them. Expect to learn to sharpen drill bits and throw a bunch of saw blades out learning though.

Frosty The Lucky. 

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  What size hole?  Adding to what Das said about cutoff wheels, a cutoff wheel on a dremel can work well for some sizes and shapes.  Just don't grind quite all the way through and tap the slug out.  Dremel cutoff wheels grab, beware.  Diamond wheels are best.  I've cut some crazy shapes with them.  

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  • 3 weeks later...

flood coolant when holesawing stainless,.

up to 6" holes in 1/4" no problem. RPM must be very slow.

Good use for camel back drill press in backgear. 

I have cut a 2" hole in a 6 sched 40 ss pipe 90 with a 1/2"  hand drill motor. That was a complex curve and required an assistant to spray the coolant.

I did recently cut a 2 3/8" hole in 3/6" CorTen with a drill motor. One hole, 3 pilots bits and two hours of drilling.  I used high sulfur content pipe threading oil 

for that one and had to apply it myself. CorTen is much harder to cut than 18-8 stainless.

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