Drill bits

[cedar_fluteman]

I have been trying to drill through some stainless steel about 1/8" thick (not knife blades just scrap steel) and I seem to just break or burn up the bits. What's the answer? Can someone tell me what kind of drill bits to use and what speed to drill? I have been using a number 44 drill bit. I even heated the metal till it was red hot and tried to drill it and it still was a problem? Maybe I am using the wrong kind of bits or something? I am drilling with a drilling/milling machine not by hand. Let me know what you think.
Thanks,
Carl

[T-Wolf]

lots of fluid and slow cutting speed.possibly hardened it with the heat.hope this helps.

[mete]

Stainless steel can work harden very easily especially type 301. Make sure the drill is very sharp and use a good feed rate , don't baby it !!

[Bearpaw]

Carl,

I use carbide masonry drill bits fed slowly with lots of cutting oil.

[ranger1]

Straight flute solid carbide bits.I have drilled threw ATS34 after heat treat and temper with these.Also use alot of oil.

[Ray Rogers]

The main part of your problem is the mystery steel. You say it is scrap stainless - if that means you don't know what it is and what state it is in then it may simply be too hard for normal drills. In that case, follow Ranger1's advice.

Normal annealed stainless steel is not difficult to drill with a common #44 HSS drill, I do it all the time. I don't follow the normal industrial recommendation for drilling though. I never drill at anything other than 250 rpm and I do use cutting fluid most of the time. If the drill is sharp and the steel is annealed that should work fine.

A small drill like that isn't going to zip right through a piece of steel (of any kind) at that thickness. Take your time and apply just enough pressure to keep the drill moving into the metal. Back the drill out to clear the chips if necessary, then go back in and drill some more.

Heating the steel red hot and trying to drill it will only ruin the drill that much faster....

[EdStreet]

head over to the tool havens and get you some carbide straight flute and carbide space bits. They run around $15 or more depending on size but well worth the investment.

Ed

[cedar_fluteman]

Well I bought this stuff at a scrap yard and it looked like it was pieces that had been sheered off of a larger sheet. I don't know any more than that about what kind of steel it is. I use it to make knife money clips. It works out great when it's done but I hate waisting so many drill bits. The carbide bits that was mentioned, are they to run slow or fast? And can you get them in numbered sizes? And where at?
Thanks,
Carl

[derek parker]

the only thing i know that will help......Cool Tool II.

[Ray Rogers]

Yes, carbide straight flute drills are available in numbered sizes. MSC and McMaster-Carr carry them in numbered sizes, Iperial sizes, lettered sizes, and even decimal sizes (odd sizes by the thousandth).

This does appear to be another case of what I am always calling the hidden cost of salvaged steel. Considering the amount of time wasted and the cost of the drills it might well have been less expensive to buy a known steel from a good source. It certainly would have been less aggrivation for you ........

[Dublin Lee]

Hi: Just saw your post. Try Rodmanandcoinc.com. Rodman drill bits are high speed and will drill through the hardest steel. On the other side, they are expensive, but you get what you pay for. dlee

[Ray Rogers]

Many people assume that the HSS (high speed steel) designation found on many drills is indicative of a high performance drill, capable perhaps of even drilling hardened materials. This is very far from the truth. HSS is usually M2 tool steel - an excellent long wearing steel - that is used in most high quality drills that we use for wood and soft metals every day. They are the most common drills and do not operate at particularly high speeds nor do they penetrate hardened steel very well at all.

The only way to drill really hard steel efficiently is with a carbide drill, mostly the straight flute variety. If Rodman carries any carbide drills at all I was unable to find them on that website. The only drills I could find were called 'multi-purpose' and those should never touch hardened steel.

If Rodman has a link to some carbide drills it would be helpful if that could be posted in this thread somewhere.....

[fitzo]

Those "multi-purpose" bits have a carbide tip, Ray. Looks sort of like a twist drill with the tip geometry of a masonry bit. The "high speed" part is their recommendation to run in excess of 2K RPM for drilling "tempered steel".

I was a little put off by the fact they say their tools are only available at "Trade Shows and State Fairs".

[Ray Rogers]

That still doesn't sound like something I'd want to rely on for drilling really hard steel. How about the prices compared to straight flute drills?

[fitzo]

Oh, I wouldn't endorse them either, Ray! LOL Quite the contrary. You know me, I'm not going to use a masonry bit when I could use a higher-precision Hi-Roc instead!