# Generic Speed Chart



## kcmillin (Feb 16, 2010)

This is something I have been searching endlesly for on the internet and cannot find a straightforward asnwer. 
 I have one of those commonly made chineese mill/drills. Mine is 2hp with a range of speeds from 120-2500. I have the standard size end mills from 1/8 - 3/4, I cut both aluminum and steel, sometimes brass, wood and acetal. I usually run most end mills at 1200rpm. 

The charts I found are all formulas, although I do understand these, they dont seem to apply to me. To many other variables, like feed rate. (This I can do by feel). 

So, Does anybody have a speed chart they use for general range of speeds for various size end mills and materials??? 

I also have a boring bar and a face mill, What speeds are these supposed to be run at?

kel


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## RobWilson (Feb 16, 2010)

http://www.littlelocos.com/home/littlelocos_web-easy_page_005.htm

Rob


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## rake60 (Feb 16, 2010)

I found a chart on this _*FigNoggle Page*_.







It is a very good basic set of guidelines.
When I know what surface speed I want.I use a very simple formula 
to calculate that the speed for the end mill. 

It is:

*(SFM ÷ Diameter of Cutter) X 3.82 = RPM*

I use that same formula to calculate the spindle speed of a lathe for
a turning operation. Just substitute the *Stock Diameter* for the *Diameter of Cutter*.

Say you are milling steel with a .500" end mill and pick the middle of the 
of the recommended speed range from the chart of 90SMF.

*(90SFM ÷ .500) X 3.82 = 688RPM*

Of course there are a ton of variables such as the number of teeth or
flutes on the cutter, chip loads, etc.. I don't waste my time with those
fine calculations at home. If it were in a CNC machine that becomes 
more important. On a manual machine you can feel what the tool is doing
and adjust your feed as you go.

Rick


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## BigBore (Feb 16, 2010)

I appreciate that, Rick. Thanks

Ed


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## mklotz (Feb 16, 2010)

If you rewrite that chart and replace each number by its value multiplied by 3.82 (12/pi), then you can simply divide your work/tool diameter into the chart value to obtain speed.

There's a speed program on my page (SPEED) that will use its own, built-in (but user modifiable) SFM chart to calculate the required speed.

More useful, at least to me, is its sister program, DIAM, which, given the speeds available on your lathe/mill will print out a chart of diameter ranges machinable at that speed for each type of material.


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## DavesWimshurst (Feb 16, 2010)

If you use 4 instead of 3.82 in the formulas given by Marv and Rick the calculations are easier and probably at least as accurate as the speed you think your machine is running. ;D
Dave


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## rake60 (Feb 16, 2010)

Simpler is always better in my mind Dave.

The 3.82 or (12/pi) are industry based mathematical standards 
that Marv and I are both familiar with. The difference between 
3.82 and 4 are negligible in a home, hobby shop setting.

Thanks for pointing that out.

Rick


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