flipping and re-registering pcbs

[jp_dt]

So....I've tried a couple different methods of registering the pcb before I route the top so that I can flip it and know where to re-zero my coordinate system so the drills match up with the bottom route. I've gotten close, but nothing that wasn't time consuming or just unreliable.

My most current method is with an adjustable fence parallel to the Y-axis, that i can square up using a dial guage, attached to my spindle mount, and jogging it in the Y-direction. Once this is squared up, I CA glue the board up against the fence, pick an x origin, drill a 0,0 hole, route & drill the top, flip it, return x to 0 and jog the y until it matches the reference hole. This gets me pretty close but not dead on...

Anyone have any better techniques they'd like to share?

[HuFlungDung]

For a fence to be useful, you need a truly square and parallel sided workpiece with very tightly controlled dimensions. Flipping the part doubles any positional error in features machined on one side versus the other.

If you can, it would probably be better to drill two dowel holes (on a wide spacing as practical) before the initial setup is disturbed. Then, make and use a jig plate with matching dowel spacing. The jig plate uses the hole locations as datum, not the edges of the plate.

Then, the program for the second side also makes use of the dowels as datum, rather than the edges of the board.

[jp_dt]

Thanks for your input. That was the first thing I tried.

My the problem with that method was that I'm using a removable platform for pcbs and the dowels don't always end up in the same place relative to the machine, let alone the shared axis of the dowels being parallel to my Y axis. I was thinking a fence that I can true up would do the trick....not so. Back to the drawing board. Maybe I need to dowel the removable platform also.

[HuFlungDung]

Thanks for your input. That was the first thing I tried.

My the problem with that method was that I'm using a removable platform for pcbs and the dowels don't always end up in the same place relative to the machine, let alone the shared axis of the dowels being parallel to my Y axis. I was thinking a fence that I can true up would do the trick....not so. Back to the drawing board. Maybe I need to dowel the removable platform also.

Now you're talking. Otherwise, you'd have to dial in the jig if it were ever removed after it was made. There are no shortcuts except the ones that you plan for.