Simple 2 or 3-axis CNC

I signed up here nearly a decade ago, almost starting a new hobby, but didn't have the time... I still don't, but seeing cheap CNC machines on Amazon is tempting... I'm interested in that type, for a type of art that I do. However, I'm not seeing any ideal products, despite a vast selection, and I have difficulty finding the time to research this more in depth. I need a simple machine for drilling holes only, no carving or anything fancy, so a 2-axis device might make sense if there is such a thing, when the third dimension (Z) is always constant (per project, so it would still need a tunable depth setting). I need to drill small holes (1/32" to 1/16") in wood (all sorts). The wood is always square, from 5" X 5" to 12" X 12", and 3/8" to approx. 1" thick. I have DXF files with points to define the hole locations. Seems easy, but I feel lost.

Hi Amdam - You will still need 3 axes for the drilling. Any of the cheap chinese "engravers" routers will do your job. Use UCNC it will be easier then Mach4 or the cam that comes with the machine. A small 400W spindle will do your job easily. Peter

"2 axis" machines don't do what you think they do... and they aren't cheap, either. They are used to drill printed circuit boards; and they only have "up" and "down" as the spindle vertical position commands.

So, yeah... peteeng is right - you will end up with a 3 axis machine.

At this end of the price spectrum, expect to do some fiddling around both with the physical mechanical hardware of the machine, and the electronics. Many of these either are set up to use Grbl as a controller; or just have the stepper motor drivers wired direct to a parallel port for connecting to an older PC running Mach 3 (which is not included... you are expected to get your own copy). As Mach 3 is no longer supported; I don't really recommend that except in unusual cases.

Grbl has three advantages: First, it's cheap - the required hardware can be had for under $20. Second, it's open-source, so if you are a programmer (like I am) you have full access to the system. Third, it's platform-agnostic; so you don't have to dedicate a Windows machine to it - it works just fine on Macs and Linux machines, too.

However, it's not as full-featured as UCCNC or some of the other CNC systems; so there are situations where it just won't work (like threading on a lathe - Grbl just doesn't do that). Another limitation is responsiveness when jogging the machine; some people don't notice it, but I do... there is a bit of lag between when your PC sends a jog command and when it gets executed. This lag does not affect running part programs; because the system buffers the g-code commands before it starts moving (so it's always ahead of where the spindle is at any given instant); but trying to do something in real-time like jogging just ends up feeling a little bit... off.

For what you are looking to do, a Grbl based solution will work; and you probably won't run into it's limitations anytime soon. If or when you do; you can remove the PCB that is running the Grbl system and replace it with something UCCNC compatible. So, if you end up getting a machine that came bundled with a Grbl based controller, I'd give it a try before moving on to something more heavy-duty... you may find it works just fine for you.

As for the machine itself... be sure to buy one that's larger than the biggest part you ever imagine running on it. Not only do these sorts of machines seem to have a way of finding uses for themselves that you didn't consider at the beginning; but you also have to factor in how you are going to hold the work-piece to the machine... clamps? a vise? direct bolt-down? ...all of this takes up space on the machine table, as well as Z axis height. Oh, and don't forget about a "spoil board" to go between the work-piece and the machine table so that you don't end up drilling into the machine itself (if commanded to, it will quite happily cut itself).

If you have the funds, I would pick a machine with a brushless spindle. Not only are they quieter (both electrically and sonically), but they (as the name would indicate) don't have any brushes to wear out. The listing for the machine should say that it's brushless... but one way to tell that it's not is if the spindle motor has only two wires coming from it (usually on opposite sides of the motor). Brushless motors require at least three wires in order to function.

You probably want a spindle that takes ER type collets. Most of the low cost machines do come with this - often ER11 or ER16. When buying, either make sure it includes collet sizes for your intended cutter bits (some kits do, some don't) or be sure to buy them as a separate item. Don't try to use a drill chuck on the spindle; they are usually too heavy for the required RPM; they don't hold as well as collets; and (unless you have some really poor collets) aren't as accurate as collets are.

If you don't already have some, you will want a set of digital calipers; and what's referred to as a "dial test indicator". For what you are working in (wood) an inexpensive set will work just fine. Also, you will want some way to hold the indicator; but you can DIY this from some scrap pieces that you may have on-hand (google for "diy dial indicator holder" to get some ideas).

There are some operational tips & tricks that I can suggest for setting up a work-piece using the machine's probe input; be sure to come back to cnczone after you've got the hardware in hand to ask about it.

:)

You are warned: CNC is a deep addictive hole ...

Cheers
Roger

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You are warned: CNC is a deep addictive hole ...

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I can exact-stop anytime I want... I just don't want to... ;)