For my Baddeley MKIII Astromech, I wanted to isolate the body electronics from my main electronics board in order to simplify and dramatically reduce the wiring and cable runs required to route all the servos and lights from the front to the rear of the droid.
The best place in the MKIII body to place a secondary board for this purpose is behind the coin slots. There is room here for a board of up to 7"x8" (17x20cm) - my board is slightly smaller at 6.5"x7" and has enough room to hold two of my voltage regular/distribution boards, a Marcduino, a wireless relay, and a control board for my CBI/DPL lights with room to spare.
A short umbilical consisting of power and a single serial connection between the Arduino and my body Marcduino board is all that's required from my main electronics board.
Materials Needed:
Nylon cutting board or equivalent to use for the electronics board - cut to the desired size
M3 countersunk screws and corresponding nuts (optional - you can epoxy the bracket to your board if you prefer)
Printed Parts:
BoardMountBracket.stl - This is the part that is attached to the rear of your secondary electronics board. The flat side goes up against the board, and 4 of the magnets are epoxied into the recesses.
Note the raised edges on each of the round bits. These are keys that are used for proper alignment of the spacers during installation. It's important that they remain intact until after installation is complete.
SpacerLong.stl - Print two of these spacers. These will provide the proper spacing on the side of the board closest to the center vent assembly.
I printed mine with the recesses facing down (using supports). This results in stairstepping of the angled surface, but is not visible as this is the surface that will be epoxied to the body.
Note the corresponding slots on the spacer lips. Once you epoxy magnets into the spacers (mindful of the polarity to match the magnets on the bracket) these slots will receive the keys on the bracket to ensure they are aligned properly for installation.
SpacerShort.stl - Print two of these spacers and epoxy magnets into their recesses (mindful to match the polarity of the corresponding magnets in the bracket).
These can be printed in whichever orientation you prefer as the angled surface is flat, but I printed them the same as the long spacers.
Note the corresponding key slots. Once all 4 spacers have been printed and magnets installed, it should be clear how the keys will orient the spacers correctly for installation.
Installation:
Use M3 size hardware or epoxy to attach the BoardMountBracket.stl to the rear of your secondary board. The bracket will need to be nearly flush with the edge of the board on the side closest to the center vents.
Note: It is VERY IMPORTANT that you have an actual board attached to the bracket. This is so that you can be 100% certain that everything will fit and to insure that the alignment is correct when you epoxy the spacers in place.
Epoxy a total of 8 magnets into place - one in each spacer, and 4 on the bracket. Be sure the polarity is correct so that all 4 spacers are firmly held in place.
Dry fit everything SEVERAL TIMES before committing to epoxying this in place.
If possible, having your astromech resting horizontally (face down) will make it less exhausting to hold while the expoxy sets. I installed mine from above while R2 was standing and it got very uncomfortable very quickly.
The epoxy may drip, so remove anything you can from inside the droid, and use a drop cloth if necessary to protect from any spills.
Apply 5-minute epoxy to the angled surface of all 4 spacers and with the entire assembly together, position it where needed and hold steady until the epoxy sets.
Once everything has cured you can safely remove the board and you'll have a convenient and easily-accessible place to position any number of droid peripherals.
JasonCharlton
