# How do you create a mounting device for a PCB if the PCB's mounting hole positions aren't documented?

I'm trying to create a place for these PCBS to mount onto:

but I don't know where to position the mounting holes for the PCB so that it can be screwed onto a standoff because the documentation for them only states how long each side of it is.

I already bought the PCBs and have a circuit soldered to one of them so I can't buy better documented ones. I've currently tried printing screw holes at varying distances to test for the ideal distance but the plastic bends too much to be reliably compared to the ideal unbending mounting board, so I would need to waste dozens of grams of plastic per failed hole distance test to make thick prints to accurately test.

Anyone here have a solution to this?

• They already have four mounting holes at the corners, so I don't understand what you mean by "not knowing where to position the holes". – alephzero Feb 23 '20 at 2:51
• I am trying to print out a surface to screw the pcp out onto but I don't know where to position the screw holes on that. – dragonking3002 Feb 23 '20 at 2:51
• under the 4 corners? – Tiger Guy Feb 24 '20 at 3:43
• Wait... you already have the boards in your hand... what’s stopping you from measuring them? A ruler should have sufficient accuracy for this, callipers would make it effortless. – Jonathan R Swift Feb 24 '20 at 7:12
• Also, we can't possibly help by providing the dimensions of the mounting holes, as you have provided a link with multiple sizes of PCB, without telling us which one you're actually using... – Jonathan R Swift Feb 24 '20 at 8:37

Measure them using a caliper. The best method will be to measure the inner and outer distance between two holes. The center-to-center distance is the average of the two measurements.

• Or measure both the right or left sides of two holes and not have to do any math or thinking at all...they’re through holes with probably 0.5mm+/- its unlikely anything more than a ruler is required as far as accuracy goes. – morbo Feb 24 '20 at 13:48