Average turning speeds.
I know there are a 101 variables, but what are good average turning speeds for steel, brass and aluminium? Or absolute minimums and maximums? Today with aluminium I found it cut pretty well from between 150 and 450 RPM (light cuts). Definitely a better finish at higher speeds. There’s a balance between speed and depth of cut of course?
The main issue pertains to the cutting tool’s life-span I guess? Too slow and deep = chatter? Too fast and light = over-heat and squealing?
Anyway, I have a feel for it, somehow, but I thought I’d see what you far more knowledgeable chaps have to say.
All Replies
Viewing 7 replies - 1 through 7 (of 7 total)
It is a matter of surface speed not rpm. In fact depending on the diameter of the part we are turniong you need to vary the rpm in order to get constant cutting velocity or surface speed. Let say a HSS tool on steel parts. if you are at 25.4mm in dia. then you need aprox. 25m/min of cutting speed, so you have:
25×1000/(pi*dia) = 25000/79.76 = 313 rpm
😕
any doubt just ask.
20m/min is ok for steel
75m/min is ok for al
25m/min is ok for casr
50m/min is ok for brass
all theese or hss tools
if you are on carbides just triple them
do your maths
i always have a small diamond grinding wheel near by , just incase , it ‘s amazing how quick the edge goes once it gets started to dull .
with aluminum you can sharpen the bit with a 10 – 20 degree back /down angle and get a nicer cut and smoth curl off , .
… depends on the bit i supose , carbid tip i hope keeps it's edge for ever on alumin/brass ,the hss is a little crappier . and shouldnt burn up .
all finishing cuts for smoothness i speed up a bunch .
Exactly what I was looking for. Thanks Jez. 😀
stainless steel or drill rod and hard stuff i slow down to <200rpm . brass or aluminum id go 500 , shouldnt hurt the toolbit ,
… depends on the bit i supose , carbid tip i hope keeps it’s edge for ever on alumin/brass ,the hss is a little crappier . and shouldnt burn up .
all finishing cuts for smoothness i speed up a bunch .
You know, I have a DC motor, power supply and controller out of a treadmill. Ive got it to put on my lathe about a year ago I just never got around to it. One of these days dammit I will get it done.
I just chuck up my aluminum or brass and use the variable speed on my lathe until it cuts easy and smooth. That is one benefit of the little Chinese machines 😛
Viewing 7 replies - 1 through 7 (of 7 total)
- You must be logged in to reply to this topic.
25×1000/(pi*dia) = 25000/79.76 = 313 rpm
😕
any doubt just ask.
20m/min is ok for steel
75m/min is ok for al
25m/min is ok for casr
50m/min is ok for brass
all theese or hss tools
if you are on carbides just triple them
do your maths
x2 🙂