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Posted by Michael Koblic on April 24, 2008, 11:59 pm
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> I made a simple spreadsheet and pdf file several years ago
> using conservative figures for smaller equipment. You can
> find it here:
>
> http://www.iserv.net/~lfisk/drillbitrpm.zip
>
This is great! Thanks for posting it.
--
Michael Koblic,
Campbell River, BC
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Posted by Wes on April 24, 2008, 6:38 pm
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>If you know a site, or if you have a list of the speed requirement for
>turning metals on a lathe, I would appreciate it. On my quick change gearbox
>on my lathe it shows the speeds, but I like to know how fast I should have
>the spindle turn if I'm turning let's say aluminum and soft steel
>maybe...The same maybe, if I could impose for a milling machine as well....I
>used to have all this stuff, but whenever my grandson visits me, and he
>needs small things, he borrows it, and then forgets to give it back to me.
>Then if I need it, I can't put my hands on it....Peter
SFM. The spindle speed is dependent on diameter, cutting tool material and
material you are machining. Surface Feet per Minute is the speed of the
material in the cut in feet per minute.
HSS 425 Aluminum 75 Steel
Carbide 1000 Aluminum 280 Steel
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
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Posted by DoN. Nichols on April 25, 2008, 12:29 am
Please log in for more thread options > If you know a site, or if you have a list of the speed requirement for
> turning metals on a lathe, I would appreciate it. On my quick change gearbox
> on my lathe it shows the speeds,
Hmm ... what lathe is this? Most quick-change gearboxes on
lathes are for setting the thread pitch being cut, or the feed rate when
turning, not the spindle speed.
There may also be a set of levers in a gearhead lathe to select
various speeds.
> but I like to know how fast I should have
> the spindle turn if I'm turning let's say aluminum and soft steel
> maybe..
Well ... there are multiple factors which are involved in
determining the optimum speed for a lathe. (And bear in mind that the
people defining "optimum" are those doing lots of work for money, so a
speed that wears out the tool a bit faster, but gets more work done in a
day is "better" for them.
And if you are threading up to a shoulder, you will want to run a
*lot* slower than the optimum speed, to keep from crashing your lathe.
But here are some factors which apply here.
1) The material being cut.
2) The material of the cutting tool -- usually HSS in a hand-ground
tool or some carbide in interchangeable insert tooling.
3) The *diameter* of the workpiece. The larger the diameter, the
faster the material is passing by the tool for a constant
spindle speed.
So -- the figures given are SFM (Surface Feet per Minute),
calculated from the diameter and the spindle speed.
You look up the proper SFS for the combination of the tool
material and the material which you are cutting, then calculate the
spindle speed using the maximum diameter of the workpiece (you can speed
up as you reduce the diameter, if you want to re-calculate. To be
precise, multiply the diameter in inches by Pi (3.14159...), which gives
you the circumference in inches. Then divide by 12 to get the
circumference in feet. Divide this into the SFM for the tool and
material combination, and this will tell you how many RPM you want --
*maximum*. And this assumes a powerful enough machine to produce this
speed. Yours may or may not be that powerful. Don't be afraid to
divide the speed suggested by four if you are not in a *production*
hurry.
To determine the SFM -- look it up on the web or with a program
(you've got some pointers for this), or buy a copy of _Machinery's
Handbook_, which has all of this you need. Pick up an old copy, it will
be as good as a new one for a hobby machinist.
Now -- there are speeds which will give a better finish, but
this is the sort of thing which you learn for your machine, tools, and
material.
Remember -- not all steels are the same. Figure that a free
cutting steel can probably be run four times as fast as an unannealed
steel like 4140.
With carbide and aluminum, you can probably run as fast as your
machine will turn -- though this might produce a poor finish as the
aluminum melts and welds to the tool.
> ..The same maybe, if I could impose for a milling machine as well....I
The same principles, except that you care about the diameter of
the milling tool instead of the workpiece -- and you also have another
factor -- chip load per tooth. Count the number of teeth on the cutter,
and multiply by the chip load per tooth to get how fast you can feed,
again if you are in a *production* hurry.
> used to have all this stuff, but whenever my grandson visits me, and he
> needs small things, he borrows it, and then forgets to give it back to me.
> Then if I need it, I can't put my hands on it....Peter
So -- visit *him*, and borrow it all back. :-)
Good Luck,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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> using conservative figures for smaller equipment. You can
> find it here:
>
> http://www.iserv.net/~lfisk/drillbitrpm.zip
>