Phillip Pearson - web + electronics notes

tech notes and web hackery from a new zealander who was vaguely useful on the web back in 2002 (see: python community server, the blogging ecosystem, the new zealand coffee review, the internet topic exchange).


Trying out the CNC mill at Noisebridge

I've been doing quite a bit of fabrication work at Noisebridge over the last year or so -- mostly electronics, plus a bit of 3D printing. One bit of equipment I've been interested in for a while is the MaxNC 10 CNC mill, which has been covered by a sheet for a while and appeared out of order, but has recently been unearthed and looks a bit happier. I gave it a try tonight, and it looks like it should be usable!

It's controlled by a computer under the desk running an ancient version of Ubuntu, with a realtime kernel for the control software. Booting it up and double-clicking the maxnc10ol link on the desktop brought up LinuxCNC. Flipping the red switch on the mill brought it to life, and the machine started up properly after hitting F1 then F2.

The axes are set up so that the origin is the bottom left front corner of the thing being milled, and the positive direction is right/back/up in the x/y/z axes:

  • X axis: + moves the platform left, - moves the platform right
  • Y axis: + moves the platform towards the user, - moves the platform towards the machine
  • Z: + moves the bit up, - moves the mill down

When homing axes, you can only move an inch in the 'negative' direction before the software will stop you -- need to rehome the axis (redefine your negative position as 0) then hit F1 twice and F2 again, then you can move it another inch. So it took a few tries to get the machine to move far enough to the left (moving the platform over to the right), and a couple to get the Y axis homed.

Once the spindle looks like it's in a safe place, you can run your program with Machine | Run Program. This will start the spindle and move through the program, then stop wherever it finished. It happily ran through its demo program.

The mill is a little small for the sorts of things I have in mind (large wooden boards cut in interesting shapes, like a lot of art at Burning Man these days) but could work nicely for PCB milling -- someone at Noisebridge has had some luck with this -- if I get some cheap PCB blanks from Aliexpress, and a couple of carbide mill bits. I suspect that the sweet spot here would be for very simple single-sided boards which are SMD-only... for example, one-off custom LED fixtures with a string of addressable LEDs and no onboard controller (or a very simple one that doesn't need any complicated traces or small pads -- so my favourite tiny MCU, the MKE04Z8VTG4, would be out, but the SOIC version would be OK, or maybe the 0.8mm TQFP44 MKE*VLD* chips).