I’m trying to use 4-40 round head screws (.202 head diameter) to mount my Uno. The screw head nearest the reset button/usb connector interferes with the 10 pin digital connector body and will not sit flat on the board. Is this normal? Do I need a special screw head, perhaps fillister head?

[image] Share tips you have come across General Electronics If you have a tight fitting head on the screw, you can cut it down with a file and a electric drill. [C.jpg] To protect the threads, thread the screw into a standoff. [screw head.jpg] Chuck the screw in …

I don't have an UNO but I always use either plastic screws or at a minimum metal screws with plastic washers. I prefer plastic screws, safe and easy to modify. You can also get plastic standoffs

All good information, but my question is is this condition normal? For those who mount Unos, do you have to turn the screw head down for this location every time? I think plastic screw heads are the same dimension as metal so the same situation would exist.

The holes are 3.2mm diameter, which is standard size for a M3 screw. But a standard M3 screw has a head diameter of around 5.2mm which is way too big for that location. I have always assumed then really meant to provide holes for M2 mounting screws.

[image] w8wer: I think plastic screw heads are the same dimension as metal so the same situation would exist. The benefits of plastic screws are: easy to trim on one side if needed will not short to anything

[image] srnet: I have always assumed then really meant to provide holes for M2 mounting screws. At the time the board was designed the header was shorter. They added the SCL and SDA pins in the R3 revision of the boards. It is somewhat inconvenient to modify the screw (really not much if you …

[image] Problem solved. 4-40 nylon screw with fillister head. Fits perfectly. Available from McMaster-Carr.

I use 2x56 stainless screws with a plastic washer, I do not have any problems.

I think there are a lot of options. I've even used double sided foam tape. My favorite are the male-female plastic standoffs. On worries about shorting, holds the board off the base. [image] I purchased a kit on ebay at a very reasonable cost. They are metric but comes with plastic screws an…

Uno mounting screw head size

Development Tools IDE 1.x

LarryD September 20, 2021, 6:33pm 2

Chuck the screw in an electric drill.

Use a file to reduce the screw head diameter.

Add a nylon washer if desired.

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Uno mounting screw head size

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