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I am planning to buy CNC mechanical skeleton without motors, spindle and controller. I will be using the CNC mainly for aluminium milling. Are there any specifications for minimum torque requirement for stepper motors and spindle to perform aluminium milling ?

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    $\begingroup$ You also need to be concerned about the stiffness of your machine. Is this CNC designed for milling metals? $\endgroup$ – Guy Sirton Feb 6 '14 at 18:44
  • $\begingroup$ Also cutting depth, possibility of lubrication/cooling liquied, cutting velocity is an important aspect when dimensioning spindles. $\endgroup$ – 50k4 Oct 22 '15 at 11:30
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Here's the important thing to realize:

While many want to size motors based on cutting forces, that approach will almost always leave you with a motor that's too weak for good performance.

Cutting force is not the limiting factor the motor needs to overcome. Rather, the limiting factor will be acceleration. Your motors must produce enough torque to accelerate the axis quickly enough to reach your machine's target speeds in a reasonably short distance.

I've written some detailed articles about how to figure all this out in Ultimate Benchtop CNC Mini Mill Part 4: Motion Performance.

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  • $\begingroup$ When editing a question or answer to make bare URLs into links, please try to avoid using here or similar as the link text. Links tend to rot and if this happens, here doesn't help anyone find the page. Often missing pages haven't been removed, they have just been moved to another location. If you give the page title as the link text then a search for that text will often find the new location. $\endgroup$ – Mark Booth Nov 11 '16 at 10:00
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There are many calculators online for determining this sort of thing, and there are many factors involved. Here is one such calculator.

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  • $\begingroup$ Your link has rotted, do you know of an alternative? Even better would be an answer which wasn't just a link of course. *8') $\endgroup$ – Mark Booth Nov 11 '16 at 9:53
  • $\begingroup$ The real thrust of my answer is that a simple google search for "milling torque formula" or "milling torque calculator" will answer this question. The question is too vague (as to the desired type of milling) to cite a specific formula. $\endgroup$ – Ian Nov 11 '16 at 13:08

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