On 2019-01-16, Rick Christian 
wrote:

> Any way..... I am looking at what other solutions some have found for
>
> 1) Mounting Pi's in racks ie: 1-3U high rack mounts like:
>
> https://www.etsy.com/listing/544554171/sbc-storage-rack-rackmount-compatible?
> ref=listing-shop-header-2
>
>
https://www.etsy.com/listing/609961042/sbc-pi-storage-bay-for-raspberry-pi?ref=
> related-1&frs=1
>
> http://www.pcsl.eu/index.php?route=product/product&product_id=306
>
> Similar items for 3 Pi's in 1U rack were made by a company in the UK, since
> EOL. Beast I can tell, and the on that had it listed as "In stock" was a UK
> company and likely won't ship to the US or it would triple or more the price
> $60..

It depends how homebrew you want to get...

I've not done this specifically for the Pi but for other boards in
the past I've used dirt cheap generic rack shelves and self-adhesive
PCB standoffs - those things stick very firmly and the result is
suprisingly robust.  For the Pi though the problem I see is that
you're unlikely to find suitable standoffs that will fit the holes
- most boards use mounting holes in the 3-4 mm range which is what
the standoffs target.

Suitable nuts/bolts through the shelf would be an option but would
probably foul on whatever is below the shelf in the rack unless it
is something shallow like a patch panel - I wouldn't fancy your
chances of countersinking them - some nut rivets come fairly
close to flush fitting but never seen them in M2.5 or smaller.

An alternative that comes to mind would be to glue a sub-base of
e.g. 9 or 12mm ply to the shelf surface.  You can then screw the
Pis in place using suitable woodscrews and cylindrical standoffs.
A quick back of an envelope calculation suggests you'll get between
5 and seven Pis into 1U, assuming you want port access at the front
or rear.  The variability comes to how you power them - the best
density would be to feed power in via the GPIO so you don't need
to allow width for the USB power input.

As for power I'll leave that to you since you are obviously best
to decide what you find acceptable.  The enclosed powers supplies
of the kind you seem to be referring are really intended for
equipment mounting and need further enclosure, but to be honest if
the screw terminals are used with insulated crimp terminals they're
generally reasonably touchproof - they'd certainly qualify for an
IP2x rating.  My biggest concern would be ensuring some form of
strain relief to ensure a tug on the cable doesn't pull it out of
the terminals.

The problem reading between the lines is you want the mains side
fully enclosed but the low voltage to be freely rewireable.  Bench
supplies with 4mm socket/binding posts come to mind but tend to be
quite tall and the budget models (the ones with a few fixed voltages
as opposed to continuosly variable voltage and current) tend to
be difficult to track down.  The final option would be to stay
firmly in consumer territory and get one of those multi-output USB
chargers with 8-10 outlets.

--
Andrew Smallshaw
andrews@sdf.org

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