Drill bit speeds

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Jan 7, 2005 | 05:01 PM

towtruck

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Joined: Jan 2004

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From: Masontown, WV

Drill bit speeds

I’ve looked everywhere I can think of and can’t find any info on recommended speeds for drill bits. Anyone know where I can get this info? The guys I work with keep burning up my bits. I tell them they are running them to fast and they tell me that’s why they say high speed on them. I would like to find a chart or something like that to show them.

Thanks

Jan 7, 2005 | 06:02 PM

sierraben

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Joined: Mar 2004

Posts: 24,418

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From: San Francisco, Ca.

Try this site-or search on Yahoo for DRILL BIT SPEEDS and go to the #1 link you see. Enjoy
DRILL BIT SPEEDS
... Drill Bit Speeds. (Sizes are in inches and speeds are in RPMs) ...
www.wwch.org/TechData/DrillBitSpds.htm - 24k - Cached - More from this site

Jan 8, 2005 | 08:25 AM

mark a.

Lead Driver

Joined: Mar 2004

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The bigger the bit, the slower it should be ran. When a bit throws long strands the speed right.

Jan 8, 2005 | 09:29 AM

Kikko

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Joined: May 2003

Posts: 95

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From: Northern Ca

Quote:

Originally Posted by mark a.

... When a bit throws long strands the speed right.

Actually, the chips should be shaped as "C's".

Jan 8, 2005 | 09:53 AM

towtruck

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Senior User

Joined: Jan 2004

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From: Masontown, WV

Thanks sierraben, Thats just what I was looking for.

Jan 8, 2005 | 10:09 AM

BicycleMark

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Joined: Jun 2004

Posts: 22

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From: Maplewood, MN

If you want to find information on Dril bit speeds, along with fastner strength or even heat treat temperatures, look in in Machineries Handbook. If you don't allready have one, go to a used book store and pick one up. The old issues continue to be usefull because the basic information just does not change over the years. It is my most used reference book.

Jan 8, 2005 | 10:29 AM

Torque1st

Posting Legend

Joined: Sep 2001

Posts: 30,255

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I have two copies, a new one and one given to me by my Grandfather that I will never part with. They are invaluable and as BicycleMark says, my most used reference book.

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Jan 8, 2005 | 11:54 AM

FLgargoyle

Fleet Mechanic

Joined: Jul 2004

Posts: 1,988

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From: Travelers Rest SC

'High speed steel' is the type of steel the bits are made of. I agree, get a Machinery's Handbook for the most comprehensive info. I generally use 50 surface feet per minute for cutting steel without coolant. Although that is on the low side, we work with tool steel, which is much tougher to cut. What is surface feet per minute? SFM equals the speed of the outside of the cutter in feet/minute. Example: a 1/2" diameter drill bit. .500" x pi (3.14) divided by 12 equals the circumference of the bit in feet. Divide 50 (the figure I gave) by the bit circumference in feet. So, .5 times pi = 1.57; divided by 12 equals .130 (feet). 50 divided by that equals 385 rpm. Another example= a 2" bit equals 6.283" in circumference, or .523 feet. 50 divided by .523 = 95 rpm. This is of course kinda complicated for everyday use, so make up a chart using these figures (or somebody else's) and keep it handy. A little oil helps the cutting a lot. Use WD 40 for drilling aluminum, and higher rpm. Another problem drilling steel is not enough pressure, particularly when using a hand drill. I am training an apprentice toolmaker, and I make him calculate the correct rpm for every tool he uses. Eventually, he will have a good feel for what is right.