"Christopher Tidy" wrote in message
...
Hi all,

This autumn I'm going to build an enclosure to house capacitors,
contactors and thermal circuit breakers as part of my phase convertor.
As I mentioned in a previous post, it needs to be strong because the
transformer will be mounted on the side, so I'm going to use 5 mm plate
and weld it together (a bit like a pole pig tank). I might make the back
plate where the transformer hangs a bit thicker. The top of the
enclosure will be removable, with a flange around the edge and a sealing
gasket underneath. I want to secure the top with stainless domed nuts,
because they look good. So I need a way of attaching studs to the
enclosure. Two problems: I don't know where I can buy studs (although I
can buy all-thread) and I'm a bit doubtful about only having a 5 mm
length of M8 or M10 thread. I do need to screw these nuts down
reasonably tight in order to seal the enclosure, and I had also wondered
about replacing two domed nuts with eye nuts for lifting, so they need
to be strong. One idea I had was to thread the holes and screw a bolt in
from underneath, so that the threaded section sticks up, then tighten
the bolt against the plate like a locknut. I know this might seem like
an academic discussion, but I want to do a good job. I'm interested to
know how you guys would do it.

Best wishes,

Chris


5 mm thick plate should be ample unless the transformer is very heavy. And
the rule of thumb on threads is that you must engage at least four threads
for maximum strength. The first and last bit of thread, of course, is a
little questionable. But a coarse thread M6 or a fine thread M8 (1.0 thread
pitch) should engage more than four full threads in a 5 mm. plate. A coarse
thread M8 or a fine thread M10 (1.25 thread pitch) would be right on the
boarderline. This doesn't mean that the threads would necessarily let go,
simply that the threads will fail before the fastener...

Jerry