Drilling stainless 303 - what noise?

303 stainless is a free(-er) machining grade isn't it? And a 3mm drill still needs a fairly high speed. My guess would be that the noise is work-hardened swarf getting caught up in the drill, but I don't drill much stainless so someone who knows better may have a different answer for you.

Peter

I would suggest going faster, 306 stainless is the one that needs a slow speed and high feed. 303 cuts nice at a bit under mild steel speeds. I would also be careful with neat oil, it can, from my experiences, tighten the bore. As previously mentioned, your noises are probably from work hardening, make sure you "cut" and not rub the surface. A good firm feed, not to heavy though. I part off 50mm dia 303 bar for weeks on end and only use soluble oil on my auto. Bob

What kind of rpm/cutting speed would you suggest? Is it worth me buying some soluble oil or can I use something else - oil thinned with white spirit for example (because I've got both lying around)?

When I drill mild steel or aluminium, my lathe makes hardly any noise. Sometimes a light "shooshing" sound which makes me withdraw the drill bit to remove swarf etc. or lower the feed rate.

I was trying to drill a 3mm hole down some 5mm 303 rod. The drill bit was new but made an awful scratching noise (I centre drilled first). I thought the key to drilling SS was low speed/high feed but the noise sounded like something was going to break.

I am using neat cutting oil.

Would using a reamer have any advantages? Horley Drill service have some new ones in their £1 charity bin so I wouldn't be blowing the budget...

which = 74mm per minute

I'm using HSS drill bits but carbide cutting tools. I tried ramping the speed up on the lathe to about 1500rpm and using the slowest auto feed I could gear, the results were reasonable - good enough for my purposes but you can still see a visible groove on the surface. I think using a "wider" cutting tool might help with this but still low down on the learning curve...

Well, as you are finding out, you need to experiment with your paticula

machines and tooling - I used to be a machinist and used almos exclusively 303 for the metal stuff. We made environmental instruments so also used no coolant. We ran the lathe at top speed, and cranked i the feed to where it 'felt' right..

It does cut fast, so ramp up your speeds.. I'd say to that your spee and feed is probably too slow so its heating up more than desired doesn't make much sound at the right rate

-- spinnett

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Had a visitor yesterday to show me what I was doing wrong. Turns out that the drill bits I was using were crap - once I switched to a better quality bit, cutting became a lot easier. Going to buy a grinder today and a drill grinding clamp...