Mounting the Arduino Uno

I have a quick question on mounting the Arduino Uno.

The Arduino Uno has four mounting holes. (1) Near DC power jack, (2) near A5 pin, (3) near ATMega328P ICSP connector, and (4) near reset button/ATMega16u ICSP connector.

All four holes are large enough to fit a #4 screw but too big for a #2. Holes 1, 2, and 3 (reference above) are no problem with clearance for the screw head above and hex standoff below. I'm not understanding how to use the fourth hole near the UCB ICSP header. The screw head runs into both the ICSP header and the D8-13 connector while the hex standoff on the bottom tries to short the SCL pin to one of the ICSP pins.

But how are you supposed to used hole #4 near the USB ICSP header?

If it's for a semi-permanent installation I get a cheap clone and remove any pins that get in the way. It usually means trimming a bit off the power jack too.

For development I have been using the board sitting directly on the desk. I'm looking to make permanent the add-on circuit and assemble the setup into a permanent enclosure. I'm laying out my own PCB shield to stack on top of the Uno. Using the Eagle Gerber files I was able to reverse engineer the hole locations and sizes. An old timer (which was many yaers ago which makes this tip really old) once gave me a helpful hint for PCB layout. Make your mounting holes thru-hole plated so the screw threads don't crew up the pcb material as easily and use a pad as large as the screw head or standoff diameter to protect the pcb and form a natural keep-out/keep-away area leaving room for the screw. Once I added the pad diameters I instantly had a clearance violation.

I shouldn't need the ICSP header, I could unsolder that (even bottom mount). But I will need the SCL/SDA just to the right of the mounting hole.

What have other been doing in this situation?

adwsystems:
…the hex standoff on the bottom tries to short the SCL pin to one of the ICSP pins.

How about a nylon stand-off or a nylon or fibre washer for that?
In fact, I recommend insulating washers all round.
I use fibre washers, as they sometimes need a little trimming to fit between components, and they are easy to cut with scissors.
As for the screw, try putting it in a Dremmel and run it against a file to reduce the diameter of the head.
Another fibre or nylon washer under the head will prevent shorting.

You don't need to use all the holes. Just two holes will hold most installations.

If you're building a custom shield, make it bigger (you always can use the space) and put mounting holes outside the Arduino. Then screw it down to the bottom of the case so the Arduino can't move.

Hi,
Would it be easier if you use metric screws, because I'd say the holes are metric.
Better fit.

Tom..... :slight_smile:

TomGeorge:
Hi,
Would it be easier if you use metric screws, because I'd say the holes are metric.
Better fit.

Yep. I use M3 nuts and bolts.

There are plastic cases for various Arduinos. With USB/supply cutouts, and lid.
Neat and tidy solution without the risk of shorting things out.
Screw the case to whatever, and just slide the board over the posts inside the case.
Leo..

If you have a 3d printer....

I've printed out a few of these and have mounted the UNO.