Was wondering if anyone has a link to a site that has a guide as to what speeds you should run certain size drill bits at?

ie i know that smaller drill bits can run at higher speeds and larger drill bits should be run at lower speeds but i wondered if there is some sort of reference or guide out there? Tried a google but nothing useful came up.

cheers,

Ned.

The RPM is also linked to the tool material (I assume you are using HSS drills) and also the feedrate.

You calculate the RPM from the feedrate.

RPM = (k*feed)/diameter.

k=0.32 for metres/min or 0.4 for feet/minute. Diameter in metres too, to keep units homogenous.

Feedrate tables are fairly easy to find. Heres a quick guide:

Material type metres/min (feet/min)
Steel 15 - 18 (50 - 60)
Mild steel 30-38 (100-125)
Cast iron 18-24 (60-80)
Bronzes 24-45 (80-150)
Brass 45-60 (150-200)
Aluminium 75-105 (250-350)

David

I should add that there are several different formulae for feed and speed calculations and they are all approximations, and should all give you roughly the same answer. A lot of it is experimentation around the suggested speed to find the best speed for the job. There is no single 'optimum' as such.

[Edited on 7/6/06 by flak monkey]

Mr Monkey

Is there anything you don't know about?

Wikipedia is your friend for things like this! We also covered tooling last year, couldn't remember the forumla though! Mind like a sieve!

David

I remember back at college some pillar drills had charts on for wood, metal or plastic and suggested speeds for drill size in each. Just after something simple and idiot proof to be honest - not getting my calculator out. Doubt I'd ever be drilling into mega hard steels so are there suggested one size fits all on the side of caution rpm's for say drill sizes 2-13mm at 1mm increments?

cheers,

Ned.

ps yes hss drills.

Something like this do you?

http://www.ibiblio.org/twa/info/drillSpeedChart.pdf

Or this:
http://www.auto-ware.com/techref/drillspeed.htm

1mm increments is really too fine. All the suggested speeds arent 'optimum' anyway. Saying there is an 'optimum' when it comes to feed and speeds on cutting tools is rather misleading, as for example there are 3 'optimums' i can think off straight away - tool life, finish or production rate. Lots of things to consider!

David

[Edited on 7/6/06 by flak monkey]

Have a look at this.

http://www.tapdie.com/html/tapping_drills_for_taps.html

quote:

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Wikipedia is your friend for things like this!

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the drill speed is an optium speed just because its a per material based number wich says the cutting speed.

to apply the right cutting speed you should increment rotating speed with a small drill, and decrement with a bigger drill..

the problem often is that you have gearing choices on the machines (lathe,drill)

sow thats where all the calc stuff is wasted.

from drill 1 to 3mm i would use 1800rpm..
(max.)

for more than 3 to 6 i would use 1000

6 - 8 for me i guess its 800

bigger then 8 i would do it with 500..

from 13 onwards i would do it with 200..

depending on your machine offcourse you could have better choices....

when using a home drill the trick done over here is that they "give gas" and let go..and then give gas and let go..

give gas = press the run button...

anyway for your drills life, i would go lower then higher..

this is as far i can remember from my mech. engineering study

Tks

thanks guys just what i was after. looking at pillar drills again and wanted to find what the advertised speeds can actually drill. I appreciate you can go quicker but are more likely to damage something, I was of the understanding that going slower is normally safer/better practise?

cheers,

Ned.

i just run mine on the slowest setting all the time

Recommended cutting speeds are only a guide anyway, there are so many variables that it is impossible to be specific.
On a small diy drill it is usually a case of having to go slower as the machine is not rigid and wont have the power to drive larger drills at the correct speed. Just remember fast speeds for ally and brass , slower for bronze and plastics and mild steel and slower still for cast iron and stainless steel .
When you have drilled a few holes in differnt materials you will get a feel for the machine etc.
Always remember to use a vice and or clamp the work correctly as drillpresses are one of the most dangerous and misused machines in a workshop and likely to catch you out if not treated with respect, i have seen a number of accidents when misused

Paul

quote:

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Originally posted by ned
thanks guys just what i was after. looking at pillar drills again and wanted to find what the advertised speeds can actually drill. I appreciate you can go quicker but are more likely to damage something, I was of the understanding that going slower is normally safer/better practise?

cheers,

Ned.

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and always wear eye protection.

I know of someone who has sight in one eye. drilling away, perfectly normally and the drill bit shattered (no idea why). Only when he took his goggles off did he notice the lump embedded in the goggles infront of his good eye.

for 5 seconds hassle its not worth the risk. I keep mind on the handle to remind me.

Right, take the cutting speed (cs) in metres per minute from flak's chart on page 1 and the drill diameter (d) in mm and insert it into this formula: -

{(cs x 1000) / (3.14 x d)} / 3.

If you're turning or milling, don't divide by 3. Job's a carrot!

ok, but how fast should you be drilling?

i mean if i'm drilling a bit of 3mm steel, how fast should i be pushing that drill into the material, i'd guess it would be 1cm a minute?