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Hi nearly finished my first electronics project and I need to think about how to mount it into a box.

I feel like I am missing something absolutely obvious with how to use PCB spacers.

Here is a picture of my box:

Proposed project box

Here is a picture of some plastic PCB spacers:

Plastic PCB spacers

The question is how to mount those spacers into the box so they don't fall out?

Should I glue them?

Should I drill holes in the box and then screw through from the other side of the box?

Any other method?

I have also looked at the spacers with sticky pads on the bottom but I prefer to reduce the risk of the PCB falling off at some point especially as the PCB is connected to a security system.

I appreciate this must be very obvious and lots of people are doing it every day but I would appreciate some direction on how to achieve this.

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  • \$\begingroup\$ Is there any space between the PCB and the walls of the box? \$\endgroup\$
    – Andrew Morton
    May 4, 2020 at 14:22

2 Answers 2

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I like to choose project boxes that have a smoother inside bottom surface than the one you show in your picture. Those specialized mount points can get in the way of trying to use the standoffs that you show.

With that said the best strategy is to get a box that has molded in standoffs. Then you specially design your PCB to have mounting holes that match these standoffs.

However if you are making a prototype or one-off hobby project then I can suggest doing as I have. I drill holes through the bottom of the box in the correct locations to mount the type of standoffs as you show. These holes are then countersunk with and a flat head machine screw inserted from the outside is used to secure the nylon standoff on the inside. If you do not plan to remove these screws for disassembly the it is possible to back fill the screw head counter sink with epoxy provided the screw head is below the outside surface on the bottom side.

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  • \$\begingroup\$ Thanks for the fast reply. I will look for a different box. I should mention I did not design this PCB I only need to connect to it and mount it into a box. Would you be able to advise on what type of machine screws would screw into the bottom of the stand offs? \$\endgroup\$
    – Remotec
    Dec 5, 2019 at 13:10
  • \$\begingroup\$ @Remotec - You need to read the spec sheet for the standoff that you choose to use. It should specify what standard screw hole size is molded into the bottom of the standoff. Note that I use stainless steel machine screws. \$\endgroup\$
    – Michael Karas
    Dec 5, 2019 at 15:00
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Typically you design the PCB to fit the box, or you make an adapter from some blank PCB material that fits the box and to which you attach your spacers. Or you just drill holes in the box.

Note that if it's an ABS box, you need to use a special screw to fit the holes in the box -- an ordinary sheet metal screw will just break the bosses.

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