Button head vs. Socket head and other various attachments

[MeanderBolt]

I am about to grab a small stock of m5 screws before my S2 gets here (hopefully any day now)(grrrr)
The buttons seem to run less expensive than the sockets, but aside from this, is there a benefit of one over the other?

Also with the pre/post insertion nuts... what makes it a pre/post. I am eyeing the shapes, but do not see why one would be pre or post. Is it a good idea to have extras of these too?

[WillAdams]

For v1 it was all Socket Head.

I believe the switch to Button Head was made to:

- eliminate washers --- used to be there was always a washer under a bolt head, now most forgo that
- clearance --- it was very close making some fit.
- pricing/weight savings --- adds up over thousands of kits
- aesthetics

Only negative was adding the need for one add't'l hex key (and less steel for the wrench's purchase as jland noted below).

The pre/post insertion nuts are just as described:

- pre are sturdier w/ more thread area, but must be slipped in before assembly
- post are thinner w/ less thread area, but may be slipped in after assembly

Having some of the latter will save one from having to dis-assemble to place one which was forgotten, which I've done more times than I'd care to count --- been tempted to drill holes in the end plates to let me slip them in.

[jland]

Socket head screws are used in heavier duty applications, as they have a larger, deeper hex socket which allows more torque to be applied. It's much easier to strip or round the hex sockets in button head screws if you're not careful.

[regressedEE]

Not to mention that socket head screws are much easier to hand tighten. I'm upgrading from a v1 to a v2 mechanical kit and keeping the socket head screws for the parts I am more likely to need to take apart and put back together but going with the button heads for stuff like attaching wheels and idlers that you generally don't mess with after assembly.