Hey guys, this IS a beginner's forum, right?

Maybe it'd be good to make a couple of details clearer. All the servos I've bought recently included some hardware that I don't see mentioned and that covers a couple of details that're being mentioned here. I took a picture of one servo with that hardware.

This servo mfg provides 3 pieces for each servo mount hole. There is a rubber grommet, a screw, and a brass fitting. That brass fitting deserves the focus here. If you look at the picture it shows the closest mounting hole having a screw in it, and the brass fitting is partially extracted.

The fitting does a bunch of things for us.

First off, it makes how tightly you tighten the screw less important. You still have to get it tight enough, but overtightening is less a problem. The brass usually stops the overtightening by resisting. Most vibration mounts have something just like this arrangement. Look closely at the vibration absorbing motor mounts for example.

Secondly, it provides a widened base against the servo tray that will help keep the grommet from squeezing down into an oversized hole. Not a big deal, but it's there.

Third, it helps keep the screw straight.

Fourth, it helps keep the grommet in those servo mount holes, especially the ones that are slots.

.............

BTW, this servo came with screws with widened heads, like they had washers already "welded" on. That's kewl, but it takes away one very useful help that washers provide.

We have a lot of places in this hobby where we need to tighten screws or bolts and don't have anything other than the resistance to the screwdriver to help us snug up the screws adequately. Washers help this like gangbusters..... Especially when we're tightening up a screw that's compressing soft stuff like the rubber grommets.....

What you do is tighten the screw until the washer is no longer free to move about. Flick it with the screwdriver tip to see. When the washer is first trapped, you can still move it easily with the screwdriver tip. Tighten it a bit. Test it again. When the washer is tight, the screw is tight enough.