On 2017-05-20, Jon Elson wrote:
Ignoramus17154 wrote:

On 2017-05-19, Jon Elson wrote:
Ignoramus13612 wrote:

This cabinet had been in my shop for something like four years and its
load did not change much. It sat by the door. Then one day it suddenly
collapsed, totally unprovoked, probably due to high winds.

https://youtu.be/UGNT6i8AIGk

Kind of amazing, **** happens when you expect it the least.

i
Well, that is a little unusual, as it had a steel back, not the typical 4
verticals with just a couple cross braces. I've had a few of those
either fail completely, or start to show signs of twisting, and I
readjusted the
cross braces to resist the twist. Your cabinet clearly twisted also as
the first part of the collapse.

Yes, i saw how it twisted a second before failing.

I would never have thought that it could be possible.
These things are actually QUITE flimsy, without the cross braces. Also,
there is some method to doing the cross bracing properly. I do not actually
know the correct scheme. but, you want to avoid the cross braces being put
in compression, as they will buckle. I do occasionally tighten the screws
on these things, as they seem to work loose over time. If the bracing
screws get loose, it will collapse if heavily loaded. The screws for the
shelves also need to be kept tight, as they also help resist the verticals
from slanting.

Jon

Much to learn on a seemingly simple subject!

By The Way your cnc boards are still working for me.