Having a cast aluminium enclosure with the 3mm wall thickness. now I need to mount this to a mounting plate which fixed in vertical walls. can I have some idea on how should I choose the appropriate fastener?

  1. Cast aluminium enclosure
  2. mounting plate for now, I have placed a 5M countersink bolt

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Thanks in advance

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  • 1
    $\begingroup$ See engineering.stackexchange.com/q/40430/10902 $\endgroup$
    – Solar Mike
    Commented Feb 18, 2021 at 10:36
  • $\begingroup$ Hi, @Nidershan welcome to engineering. You need to give more information on what are the specifications and what you want answered. A few questions that come to mind are: what are the loads on the encosure? are there any vibrations that will set the fasteners loose? Do you want a calculation for the number and size? Can you make changes to the enclosure's design to select different types? $\endgroup$
    – NMech
    Commented Feb 18, 2021 at 11:48
  • $\begingroup$ @NMech thanks for the response. Enclosure can't be changed. this mainly mounts on the railroads it should withstand 20g RMS shock. this is the only way I found to mount the enclosure to the plate since I have to maintain the water-resistance. $\endgroup$ Commented Feb 18, 2021 at 12:13
  • $\begingroup$ Total enclosure weight around 800g $\endgroup$ Commented Feb 18, 2021 at 13:15
  • $\begingroup$ can you use an angle bracket and thus mount the bracket to the bottom of the sealed enclosure, where it seems to have the two larger clearance holes at the corners? $\endgroup$
    – Pete W
    Commented Feb 18, 2021 at 21:21

1 Answer 1


The easiest way to maintain water resistance is to not puncture the enclosure.

It looks like the box has holes extending through the cover down to the bottom, I'm guessing these are specifically for mounting? (The 2 large holes). Use those if you can.

The next best option would be to attach the box so that the bottom is against the plate, and screws come in from the outside into the screw holes that extend from the top of the box to the bottom.

box screw placement diagram

Another option is to attach the plate with screws from the inside. Place the holes so the inner surface around the hole is flat, and then use sealing screws.

sealing screw

Depending on how water proof you need the box to be, it might also be viable to just mount the box using angle brackets so the screw holes are facing the ground. Although not fully waterproof, water would be unlikely to get in that way.


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