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Drilling stainless steel

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mhh:
Drilling stainless is not always easy!

Cheap carbide tools have a tendency to workharden the material, some years ago before carbide became as fine grained as it is today the best way to drill stainless was hss.
When drilling stainless you want to avoid the drill rubbing.

My suggestion is OSG HSS drillbit. They have a series of drills called RDS and they are just amazing, the way they grind the tip really does wonders with stainless.

Like everyone else said it should be cobalt HSS

TLGriff:
Are these through holes or blind holes you are drilling? If they are through, you may want to consider using tubing instead of round stock.

Tom

Francalves:
Hello
  When I need to use a drill boring stainless drilling stone (those used for drilling wall) as a sharp HSS is cheap and results but do not have much precision, bat bore any very hard steel

Gayate:
I sorry for bump...just my two cents for this old thread..
The key to drilling stainless is to use a drill bit which digs below the surface of the material so that it always cuts new ss, instead of slowly eating away at the surface, causing heat, which will work harden the stainless. It makes sense, but I don't think I have drilled stainless with these, yet. A HSS drill or bits https://mechanicguides.com/best-cobalt-drill-bit-sets/ with a less than perfect design, for stainless, may give poor results on stainless, where a HSS drill with a better design could cut just fine. If you are just buying a couple drill bits, go with the cobalt HSS if you think they will be better.

Carbide is a no go for hand drilling. It is too brittle, and I have learned that the hard way. Another reason I was willing to try noresman  HSS, is that they claim their bits are a bit, no pun intended, tougher than common HSS but also flexible enough to hold up to hand drilling under less than ideal conditions. I prefer to drill items on the mill/drill and use an air mister to keep the cutters cool, but there are plenty of times I have to drill by hand with my V28 cordless. On thin stainless, the right bit shouldn't heat up much. I thought about using some of the mist coolant in a spray bottle, since it is much cleaner than using oil, and it keeps the bit much cooler.

Welding those joints wouldn't be much fun, even if you did have the equipment and some experience. That is some thin tube and even though I have tig and mig welded for years (very little stainless), I would expect to have a learning curve. Also, Twist drills in sheet metal tend to make out of round holes. If you must use a twist drill, use Norseman/CTD drills. Their high molybdenum content makes them well suited for SS. Otherwise a good cobalt drill. Lots of feed pressure, low SFM. Use machinery's handbook for the formula for RPM to get the right SFM for your size.

However, if you need a nice round hole, Hougen makes a set of mini rotobroaches. They work excellent, just center punch and drill.

Best lube I've found is Union Butterfield, followed by Tap Magic. Avoid the dark sulphur oil on SS.

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