Just got a couple more Uno boards and find they come with a nice base. But no info on the screws. The ones for mounting the base to whatever are same as holes in arduino and #4 fit well. The ones aligned with the Uno holes are a bit under size. A #4 machine screw fits and forms it's own threads and seems to work well - a snug fit but not excessively tight. Wondering if there any info on what was intended to be used with these holes? Where can I find some documentation on the bases? I would like to have the hole pattern for the Uno and the Mega bases.
Not quite what I am looking for. I have that. I am looking for details on the plastic base now shipping with Uno and possibly shipping with Mega.
Well, the holes will be in the same place, won't they?
I don't have any info on the plastic bases. Are they coming from Arduino?
Is there a link to them at the Arduino store?
There is nothing for the bases as they are generally meant for transport and do not come with all boards.
AFAIK all screws were or are meant to be metric in size.
That your own screws as you said cut thier own way in would verify they were indeed metric (to start with)
My bases are just screwed down to a plywood base with very small self forming screws.
If you want to use the base on standoffs than whatever fits through the holes
The picture posted by ballscrewbob shows the plastic base. It uses the holes in the Arduino and also has other holes for attaching the base to things (enclosure, larger base, etc). I was planning to drill the holes for those in an enclosure with a small mill so having the exact dimensions would be handy. I could just use standoffs instead of the base.
The screws I used are standard US 4-40 screws. They worked very well - seemed to be large enough for good thread engagement but not overly tight where I was concerned about cracking the plastic. Most of the docs I have seen state M3-0.5 or UNC 4-40 but that is for the board without the base. The holes in the circuit boards are large enough to clear either.