[liamo76]

Hi Everyone,
Recently purchased a mini lathe which i enjoy using. I'ts the first time in over 20 years i've done any metal turning and i'm learning everything from scratch!
The main thing i can't seem to find is turning speeds for differant metals.
I know it's fairly critical the speed is right and will effect the end result.
I don't know anything about metal grades but i've been using aluminium, steel, brass and plastics.

Thanks,
Liam.

[jackson]

see if this helps
sfm = rpm x dia / 3.82

rpm = 3.82 xsfm / dia

ipm = ipt x no. teeth x rpm

ipt = ipm / (no. teeth x rpm)

ipr = ipm / rpm

[jackson]

sfm depends on the material and the tool your cutting with

[jackson]

try this

[handlewanker]

Hi Liamo, if you want to have the speed range always available to hand try using the method I learned 40 years or more ago.
This will apply to drilling, turning and milling, using HSS.
Start with mild steel at 1' diam,or as in OZ 25mm diam.
The rpm is 250.
Evrything hinges about this.
!/2" or 12mm is double at 500rpm, and 1/4" or 6mm is 4 times or 1000 rpm.
Going the other way, 2" or 50mm diam is half, or 125rpm etc, etc.
For other metals:-
Alluminium = X 2.
brass = X 2.
cast iron = X 1/2
Phosphor bronze = X 1
Silver steel = X 1/2
If you're using carbide tools then you can double the speed as for HSS tools.
Plastics are generally faster but friction can lead to the swarf melting on the tool.
If you just remember the 1" diam rule then everything else is relative.
Feed rate is a different matter and depends on the set-up and rigidity of the machine.
Ian.

[liamo76]

Thanks for all your replies!!
It's not as simplistic as i first thought, and probably typical of someone like myself new to machining.

Cheers,
Liam.

[handlewanker]

Hi Liamo, don't worry mate, we all had to learn and after a short while It's just like eating a Mc D's burger, if you try to take too big a bite you'll choke on it.
Ian.