[CaptRR]

Hello All,

Been doing PCB's for years, though usually using the tried and true laserjet and deadly acids method

Anyways, I have a mill, and wanted to start playing around with PCB milling but have a few questions.

First, I have aspire and mach3 on the mill. I was wondering what I do with the files that pcb-gcode seems to generate. Do I try to dump them directly into mach3, or run them through aspire first?

Second, alignment. Most of my projects are two sided boards, so I was wondering what techniquies you guys use in order to align the other side of the board. I know with wood, I would usually drill some holes in all four corners, evenly spaced, and use them as guides when I flip the workpeice.

Thanks

[Bubba]

CaptRR,
OK, as your using Eagle and the pcbgcode ulp, It generates the Gcode (assuming your using the right profile) to dump directly into mach. No need to run it through anything else to get it to run.
Alignment,
OK, I use a fixture that holds the raw board in one place. I use G54 as the top side and the origin is located at the lower left corner of the board. When I flip the board over, the same origin point is now at the lower right hand corner of the board and I am in G55 fixture mode. In order to do this, I have customized the post processor files in the ulp to accommodate this.
What I have done is made a pocket in a piece of derlin and used this with a vacuum pump to hold the board flat. I also use "autoleveling" software to accommodate the imperfections of the pcb.

[CaptRR]

Bubba,

Thanks for the response. I am still a little unclear on the alignment. I think I see what you are doing, by flipping the board and making the origin point on the bottom right, it doesn't matter what the size of the board is (or even the slight size differences between board). That sounds like it would work pretty good (assuming I could make sure the board is strait of course) Is their a setting in pcb-gcode that can change this origin point for the flipped board?

Again, thanks for the info. Truth is I don't really expect this to work all that well. The mill was designed to cut 4 foot sections of wood, and if its able to make a trace that is electrically sound I will be surprised. Then again, it worth a shot, and if it doesn't work I am just out of some pcb etching mills, and some copper boards.

[Bubba]

CaptRR,
I milled a shallow pocket to hold my pcb stock. By doing this, the bottom edge is always touching the same edge of the fixture and as the board is flipped over, it is also registering on the same origin corner because that is the way I milled the pocket in the fixture and it is never taken off the machine. When milling, I saved the fixture offsets. So when I power up, I home the machine and then load the offsets and am ready to go!
For testing purposes, I would use double sided tape to hold the pcb down on a section of spoil board that has been milled flat. Again, you can mill a pocket to use for alignment. Don't be surprised if your depth varies though as the boards are not truly flat!!! I also use an autoleveling software to handle that part and probe the pcb.