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Having used some big, old, manual Bridgeports in school, I was looking into getting a small mill (manual or CNC) for hobbyist home use on metal and wood. I was surprised to see many CNC milling kits on Amazon for quite cheap ($200-600 USD) whereas the the cheapest manual mini mills seem to be roughly 400-1000+ USD. My question is why the cheapest CNC mills cost less than the cheapest manual mini mills? (I am presuming the entry level for manual and CNC mills are the same except obviously the key automated part --- ie that RPM, vibration, stability are similar, but please comment on that in your answer if that's a confounding variable).

EDIT: My question originally had two parts with the second asking if there was also a performance difference between entry level CNC and entry level manual mills, but since none of the answers addressed that in much detail and it's sort of a separate (but only possibly related) question I have removed it.

rfii
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    It could be the market. They may sell less manual machines. I will tell you this though: I watch the machinist at work and he laments not having a manual machine available when making prototypes. Certain things you can only do on a CNC but a lot of things you can do a lot faster on a manual since you just throw it on and do it rather than needing to write a program and locate everything. – DKNguyen Jan 21 '21 at 01:32
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    A stepper motor is cheaper than making accurate smooth graduated hand dials, perhaps? (Due to economies of scale) – Jonathan R Swift Jan 21 '21 at 11:23
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    "*a stepper motor is cheaper*" .... and not as good compared to the motion on a pro machine (whether manual or not) – Pete W Jan 21 '21 at 13:57
  • @DKNguyen especially when you do one off prototypes. Programming, locating and verifying that the program is safe is a lot of work for one part. So having both is a boon. – joojaa Jan 21 '21 at 19:26
  • The speed advantage for manual when prototyping, making art, or playing around is exactly why I am asking this. – rfii Jan 24 '21 at 03:58

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The two existing comments are correct IMO, it's mostly due to economics. The price to produce comparable CNC and manual machines might be close, but the demand for CNC's is much greater than manual machines.

Every shop I've ever been in, from mom & pop places to 1,000+ employees, has been 95% CNC with manual machines reserved for tool & die making or the scrap yard. It's an infinite loop type scenario as well - the CNC machines are more profitable since they can be run lights out, so companies mostly look for people who can run them, so trade schools teach focused towards CNC and less advanced skills of manual machining, so there are less manual operators available, so more companies get CNC's since that's the only thing a majority of machinists can run anymore.

The "guts" are more complicated for manual machines, from a mechanical perspective. More gears, clutches, bearings, lubricant, seals, etc. These all cost more than a few microcontrollers to run a CNC.

jko
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    CNC's do have significantly more machinery. more elaborate tool changers, tool holders, chip removal, coolant, and (often) guarding. but big yes to the overall point here, especially trained people... – Pete W Jan 21 '21 at 13:52
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    I stand corrected. I would imagine for a $200 Amazon CNC mill you're not getting a lot of those features though. – jko Jan 21 '21 at 14:11
  • I'd suppose then that if machinists are so expensive then it doesn't make much sense to equip them with a shoddy mill that would just take them much longer to do anything, but that's wild 2nd order speculation. – rfii Jan 24 '21 at 04:03
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Making a machine CNC ready has a neglible cost. Electronics cost nearly nothing, and are easy to do when your not aiming to super quality. All of the moving elements can be simplified because you dont need to present user interface through mechanical couplings and dont need to worry about user safety.

So a bit counter intuitively cnc machine can be simpler than a equivalent manual machine. Now that is to say the CNC does not even need to be equivalent to a manual machine. It can also be made for much lighter loads than a manual machine would, since there is a limit on how slow a human can be expected to go. So a cnc that just takes really slow passes on a PCB does not need to be much suturdier than a 3D printer.

Then theres the economics. A super cheap and light CNC is actually semi useful as one operator can batch many machines. Whereas a manual is still limited by the cost of a operator so it does not make sense to invest less into that use. But again this depends on market, CNC is obviously good for production runs. But not necceserily for very small scale or toolroom, modelmaking (die) or prototype work where a manual tool is still invaluable. Especially when paired with a CNC or two.

joojaa
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