Tapping stainless

[david gregg 1Participant @davidgregg1]

[david gregg 1Participant @davidgregg1]

I have just finished tapping 75 m4 blind holes in 12 mm square 316 stainless steel , this was a job for a local wholesale butcher who was unable to get these spare parts because off the present lock down .It was a nerve wrecking business as I had no spare material and there would be no chance of removing the broken tap .I drilled the holes 3.4 mm this is .1 over the recommend size but it certainly worked for I also used a spiral flute tap which is recommend for stainless ,but I think after 75 holes it is getting slightly harder to tap

[Clive FosterParticipant @clivefoster55965]

david

I'm now a fan of serial type taps for this, and frankly, most other sorts of thing. Noticiably easier to turn so, presumably, less likely to gall up and break.

I get mine via E-Bay from davethetools. Vokel brand and recommended for stainless steel.

Clive

[Mick B1Participant @mickb1]

Spiral flute taps are brilliant for blind holes – the way they hook the swarf out seems almost miraculous. But I've only used them on aluminium alloy – I'd think stainless could present challenges. Sounds like you did a cute job.

[old martParticipant @oldmart]

What lubricant did you use?

[jimmy bParticipant @jimmyb]

I tap and die a lot of 304 stainless (mainly M6). I use Rocol RTD liquid, I've tried loads of other cutting oils, but none work as well on stainless.

Jim

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