[HH] The Othermill: a desktop CNC

[Tom Metro]

Greg London wrote:
> it appears to be limited to boards that are single sided...

Correct. They explicitly state that in the FAQ, which I quoted:

  Can I make double sided PCBs?
  We are working on double sided PCB functionality for Othercam. It
  probably won't be ready for the initial release but it is in the
  works.

No doubt the challenge is establishing registration after you flip the
board. The page made some mention of some mechanism they use to
automatically calibrate registration of the work piece (in the general
case - not specifically for 2-sided boards), but never explained how it
worked.

That blog about publishing prior art for patents that I linked to
recently had an idea to use a video camera and image processing as a
feedback mechanism in 3D printers. Conceivably a mill like this could
use an image of the board to orient itself to the blank, and as the
first step, drill a set of holes that can be used for registering the
2nd side.

Even if it can do both sides, you're still stuck with the limitation
that you don't have plated through holes, which means soldering each pin
on both sides. I remember some PCB mill in the 80s actually came with
little eyelets that you crimped into the holes.

Still, there is a lot you can do with single sided boards and some jumpers.


> ...and only use surface mount parts.

I wouldn't want to be limited to only surface mount, but using mostly
surface mount wouldn't be so bad.


> None of the PCB pictures show holes for pins or vias.
> And I didn't see any mention of "hole" or "drill" in the text.

They do mention that it has a Z-axis, so I don't see why you wouldn't be
able to drill.

Although if you wanted to avoid your base from turning into swiss
cheese, you'd need to put some scrap under your PCB. Given that the
recommend way to hold down your PCB is double sided tape or hot glue,
adding a layer under the board shouldn't be a big deal.


One thing they do gloss over in the project description is that tool
changes are manual. So it'll never be like pushing a start button and
coming back after lunch to find a completed PCB, routed, drilled, and
cut to size.

They pictured it creating wax molds, which could then be used to cast
high-strength metal parts. That's intriguing, but casting is not exactly
a desktop process. :-)

 -Tom