lathe speeds

[brickie]

hi anyone know where i can get a list of best lathe speeds for various metals,ta.

 

[Tin Falcon]

Just about any basic machining book will have such a chart.as will just about any machining reference book.
there is one here for your convenience.
http://littlemachineshop.com/Reference/CuttingSpeeds.php
I suggest you also read this thread
http://www.homemodelenginemachinist.com/index.php?topic=9413.0
and download some of the books. you can print pages as needed and place them in a notebook.
Tin

 

[John Rudd]

download some of the books. you can print pages as needed and place them in a notebook.
Tin

Better still, do what I do , and print off the sheet(s) you want and have it laminated...Hang it off a peg adjacent the machine, there when you need it..

 

[mklotz]

Here's the one used in my speeds and feeds programs. All numerical values are in SFPM = surface feet per minute.

ALUMINUM AND ALLOYS	200	300
BRASS AND SOFT BRONZE	100	300
LOW CARBON STEEL	80	150
MEDIUM CARBON STEEL	60	100
HIGH CARBON STEEL	50	60
TOOL AND DIE STEEL	40	80
ALLOY STEEL		50	70
MALLEABLE IRON		80	90
SOFT CAST IRON		100	150
MEDIUM CAST IRON	70	100
HARD CAST IRON		40	60
COPPER			60	80
HIGH TENSILE BRONZE	70	90

 

[brickie]

thanks for your replies

 

[rake60]

There's a simpler way.

Let the metal tell you.

If the material is steel the chip color should be somewhere between straw color and blue.
If the chip is the same color as the stock it is running too slow and the tool will chip.
If the chip passes blue and becomes purple, it's running too fast and the tool will burn up.

Aluminum is easier.
As long as the chip is moving you're good.
If the chip starts to gall up on the tool it's running too slow.
There is no such thing as too fast when machining aluminum.

Brass and bronze go to the other side of the spectrum.
There is no such thing as too slow for rough turning, but for finishing you need to rev it up.

Stainless steel is an entity of it's own.
303 is treated the same as any mild steel.
There's a machinist's saying in regard to 304, but I won't quote it here.
Let's just say it is user unfriendly.

Cast iron cuts like chalk up to it's speed limit.
If the chip discolors or the tool starts to glow red the damage is already done.
You have exceeded the speed limit.

The numbers in the book are a great reference point but the material in front of you will tell
you more than any book ever could.

The color of the chip, spark of the cut or smell of the cutting fluid will tell you a lot more than
any book ever could.

Get a few pieces of junk material and try different speeds.
Intentionally cut them way too slow and far too fast.
Watch and see what happens for yourself.

The metal will tell you what it wants.
All you need to do is listen to it...

Rick

 

[Jasonb]

The charts on this page are easy to follow as they are in rpm for each diameter, saves having to work it out from fpm etc. They are also based on hobby machines rather than commercial rates that suit big machines and fast production times.

Jason

 

[Tin Falcon]

If you want a nice chart and are willing to spend a few bucks looks here http://www.littlelocos.com/home/littlelocos_web-easy_page_006.htm
Todd is often a vendor at Cabin fever. I have one of these charts behind my lathe. it also includes a ready reference for tool grinding.
Tin

 

[steamer]

Yeah, what he said.

Pat J

Pat couldn't have said it better....spot on Rick.

Dave

 

[Kmot]

I want to thank those of you posting in here.

I have not had good luck getting smooth finishes on various metals I have turned on my lathe. After reading this thread and looking at some of the charts, I was machining some bronze and was getting a crappy surface finish. Recalling this thread, I reset the lathe speed up one notch on the pulley and wow, like magic the surface started machining smoooooth and shiny!! :bow:

 

[Tin Falcon]

Knot that is why the basics are soo ... well ... basic.
Tin

 

[shred]

Correct speed is something that it takes some people (me included) some time to get. I'd be turning stuff way too slow, not trusting the bits and machine to do what they really want to.

 

[AdShea]

Just to add if you are stuck cutting 304 the trick is to cut with lots of feed and not too fast (I don't know the numbers but it's opposite what you do with Al). The surface layer work hardens so if you don't cut deep enough you'll just chew through your cutter.

 

[Tin Falcon]

Home shop Machinist May /June 2012 Pggs 57-59
Tin