As I slooooo-ly progress on my RR, I’m faced with mounting several printed circuit boards, to control such things as DCC reversing sections, occupancy detection, and the like, to my benchwork.
Is it acceptable / safe to screw these (flat side in / component side out) to a joist or girder? I don’t want to have them hanging down on the underside, to get bumped when working underneath! But I can’t imagine everyone buys & uses some kind of an enclosure box for them, or do you?
If you have a plywood base, you can screw those PC boards to it using drywall screws and nylon spacers. If you check at your local electronics supply house, you should be able to find nylon spacers in different lengths. Select a spacer with enough inner diameter for a drywall screw to pass through it, and long enough to allow about 1/4 inch of screw tip to penetrate the plywood. Spacers are also a good idea if you’re going to mount PC boards to the framework.
cacole’s suggestions are right on. To make later maintenance easier, you might put the circuit boards on their own backings (1/4" plywood) that is attached at the top/side to the benchwork. This makes it easier for you to remove it from under the layout, then do the delicate work on your workbench. You might even attach a terminal strip to the backboard so that connections under the layout are not directly to the circuit board. If you have several that are identical, make their layout/backboards exactly the same so a failure does not stop an operating session longer than the time to swap out the board. Plan a little for the future, and you’ll be very glad you did!
The best option I saw had the circuit boards on a piece of plywood. This piece of playwood was attached under the front edge of the benchwork with a hinge. A pair of sliding door bolts held up the other side. Leave enough slack in the wiring and you can open the bolts and swing the panel down for easy access from the front.
I did as rrinker suggested. I had the hinge close to the front of the benchwork so that I could sit in a chair and work. I did this for all my electrical work. I used Tortoise swtich machines and ran the 8 wires to a teminal block on the plywood. It was much easier to work from a chair than kneeling on the floor.