Drill bit speed?

[stephen4785]

How do you determine what speed you should use to drill through different metals? Iv always heard that the softer the metal the faster the speed but other than that Iv just done trial and error.
Thanks

[Blue88Coupe]

How do you determine what speed you should use to drill through different metals? Iv always heard that the softer the metal the faster the speed but other than that Iv just done trial and error.
Thanks

http://bbs.homeshopmachinist.net/showthread.php?t=40724&page=2

click that and scroll down a little ways. They've got what tip angle, what speed for what metal. I've been doing some bit research the past few days and that page was really helpful.

-Nick

[turbostang]

There's lots of things that affect what speed you need to run at. Obviously one of them is material, next bieng WHAT you are drilling with - cobalt, HSS, carbide etc... and lastly, if you are drilling by hand.

Generally speaking, surface footage for twist drills is like 40-60SFPM. Rigidity of the setup has a LOT to do with what you can get away with. A good rigid setup and lots of coolant - those numbers can double or triple easily.

FWIW, Stainless is the WORST material to work on.

Rpm = sfpm x 3.82 / part diameter or cutter diameter


Sfpm = rpm x part diameter or cutter diameter /3.82


Rpm = sfpm / part diameter or cutter diameter x 0.262

[8mpg]

yeah..I just go on the slowest the drillpress will go

[Blue88Coupe]

yeah..I just go on the slowest the drillpress will go

Read up on "work hardening."

[RuStYpNuS]

Like Brooks basically stated it depends on the material and the type of tool your using stainless steels are super hard so you feed/cut slower than aluminum or brass. 1018 or 1045 is fairly softer than 4140. If in doubt use coolant and don't go so fast that you burn up your tool.

[YALE]

Read up on "work hardening."

That's a huge deal with the higher nickel stainless alloys, like C-22, and Inconel. I worked on a pipe-fitting crew out of highschool, and we ruined a lot of facing bits on .049" wall C-22 tubing. It was crazy how fast that stuff would harden, if you didn't cut it just right.

[turbostang]

Once you've work hardened a piece, generally the only way through it is by grinding the affected area and starting over. If it's a drilled hole, you have to sharpen your drill, turn it REAL slow and get after it - you'll probably dull it again. You have to have a keen ear to know when it's giving up so you don't work harden it again.

[Grape]

i just love watching somebody take a hand drill and hold it wide open.......makes me cringe

[projectPONY]

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