Dave Plowman (News) wrote:

A 2mm wall thickness ain't going to give much of a thread for M5 bolts.
The usual way would be to weld in bosses to increase the thickness.

If you thought Apple were the masters of the "some sequences shortened"
video, try this

http://youtu.be/dKeoFqSddaI?t=49s

As a rule of thumb, you want about the same thread length as the
diameter as a minumum.

Contrary to my earier reply, they do seem to use an insert on the M8
bolts, I'll check when they arrive, if they use them in the pre-made
posts, then rivnuts may be the way to go for the M5 holes.

http://youtu.be/yZxyucLqXCA?t=10s