Having watched every relevant You-Tube video I could find (and I especially appreciated John's),

Having watched every relevant You-Tube video I could find (and I especially appreciated John’s), and having read the questions and comments here, I have succeeded in selecting a CNC machine (a Chinese 3-axis 3040), swapping a TinyG into it, setting up the Tiny G, getting it to communicate with my laptop through Chilipeppr, desiging a schematic and board with EagleCad, importing the board to Chilipeppr, and producing GCode from Chilipeppr, I am stymied in actually cutting the board. (Given my non-technical background and only very recent interest in programming, arduinos, etc., I am proud of even this level of success.)

My immediate hurdle is getting leveling data for just the board area. I can’t figure out how to properly specify the board location and dimensions. In the auto-level drop down menu, I see the starting and ending X and Y locations, and infer that must be relative to G53, which I infer is the machine coordinates, not the board coordinates. And I use the Set Mch Zero button to set those coordinates (with the head at machine zero) to zero. I also set the board coordinates to zero (with the head at the front left corner of the board, with the tool just touching the board, although I assume the z doesn’t matter because it is going to get leveled anyway). Then I figure the offset by comparing G53 to G54. In explaining this, I can’t imagine why it isn’t working and well try again (at which time it probably will work), but would appreciate any insights.

The next hurdle will be positioning the board for cutting the other side. In all the video’s and reading, I haven’t seen a good trick for doing that. One guy drilled some reference holes and that is the leading contender, but since it seems no one else needs to do that, I infer there must be a better way?

Lastly, I don’t understand the purpose of putting a BBB in, the way John did. Is it merely to allow wireless access to the machine?

Thanks for any advice,

Maybe post a screenshot of your board with the auto-level turned on so we can see what you mean by not being able to get the dimensions.

Doing 2-sided is still not something the Eagle BRD widget supports. It’s a big wish list item, but nor I or anyone else has had time to add the features. Hopefully somebody is willing to volunteer on that one. @raykholo made some really good progress a while ago.

For the BBB, I use a Raspberry Pi 3 now, so I would recommend that. The reason to use it is so that SPJS can run on Raspi in your CNC box. Then just connect to its IP address from your laptop running ChiliPeppr.

I never got that far, I just made a simulation of a PCB flipper I had in mind. But yeah, alignment holes is the way to go. If you don’t want to do them in each individual board then make a jig style frame that squeezes your copper clad board that way you just have to flip and align the panel.
Here’s what I had in mind: https://www.youtube.com/watch?v=QB2b2S0Mtl8&feature=youtu.be