1. ## Formula

Somebody know the formula for feed vs speed
Thanks

2. Would help if you tell us exactly what it is that you need!
Speed = how fast you are travelling?
Feed = Speed at which the tool is moving through the cut...?
RPM = how fast the spindle is going!
Cheers
Brian.

3. That is my question, I want the formula because I want to apply it to any speed, for example if I use 300 rpm or 1500 what gonna be the feed or if I put F19. how much gonna be the speed for any material
Thanks

4. Well...

In the METRIC World you can use the following formulae:

RPM = [CS x 1000] / [Pi x Diam]

Where CS = Cutting Speed in Metres per Minute
Pi = 3.1416 (approx)
Diam = Cutter Diameter in mm

FEED = RPM x z x Fz

Where RPM = Rev Per Minute (Formulae above)
z = Number of Teeth (Flutes) on your cutter.
Fz = Feed (in mm) per Tooth per Revolution.

An Example:
CS = 200m/min
Diam = 40mm
z = 6
Fz = 0.3mm

RPM = [1000 x 200] / [3.1426 x 40]
= 200000 / 125.664
= S1592 (rounded to nearest whole number)

Feed = 1592 x 6 x 0.3
= F2865.6

Hope this helps.
Cheers
Brian.

• It work the same for Inches?

• Well, since you guys are still calculating things in the dark age units... 10 fingers = Metric System, so much easier to count than in units of 12!

RPM = [3.82 x CS] / Diam

Where CS = Cutting speed in something called "Feet" per Minute
Diam = Cutter Diameter (or shaft) in some unit called "Inches"

So using previous example:
CS = 656'/Min
Diam = 1.5748"

RPM = [3.82 x 656] / 1.5748 = S1591

Same RPM but using weird screwed up units

Formulae for Feed is the same! But expressed as feed in inches per minute.
Cheers
Brian.

• Originally Posted by broby
Well, since you guys are still calculating things in the dark age units... 10 fingers = Metric System, so much easier to count than in units of 12!
I do believe that the decimal time system was an epic failure....

Dozenal rules!!!!!!!!!! (60pergross of the time, anyway)

DP

• Originally Posted by christinandavid
I do believe that the decimal time system was an epic failure....

Dozenal rules!!!!!!!!!! (60pergross of the time, anyway)

DP
LOL yep I agree that the decimal clock is (was) crap... but at least telling the time is the same all around the world!
Can't say the same for dimensions... imperial -> metric -> imperial gets screwed up all the time! (Just ask NASA where their Mars probe is... oh that's right they screwed up a conversion and lost how many millions of dollars worth of probe?)

Cheers
Brian.

• And where is austrailias probe?

• Hey at least I know how to spell "Australia!"
As for our probe... Bend over!!!

We might not have one up there, but it is NOT "Lost In Space!"

Stupid Yanks!!

• Thanks Broby

• I like that one, Bri

We can look back at the first moon-walk, Aus saw it before them as well
They even dumped "Space-Junk, sorry Lab, on us

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