Re: V-Plate Hubs

["J & D Goldman" <jmgoldma at dwx dot com>]

Interesting points about hubs.  A few observations:

I think a dome garden shed would be one way to get people to think
about domes.  I was at the local salvage yard after a windstorm, and
the attendent said he had never seen some much garden shed steel come
in. It wasn't that trees fell on them, it was the wind took down a lot
of "Sears" garden sheds.  I think dome sheds would have come through.
Yes, lots of people will immediately reject a structure that has a
round base and sides that are not straight. Well, if that's a *big*
problem, various octahedrals can be made to sit on a square foundation
just fine, and a riser wall does help a bit on the straight side
issue, albeit at some loss of stability.  Part of the challenge would
be to get the steel shed people to realize that cutting triangles is
just a matter of cutting a rectangle at something other than 90
degrees, but I'm sure the big hurdle is convincing the fabricators
that anyone would buy them.  Until someone has their own success in
the market place, we won't know what the numbers look like until dome
sheds are on the picture board at Menards along with all the
rectilinear steel and vinyl sheds.
    As far as the lumber connectors, yes indeed, that's another way.
If one could play off the gazebo connector idea, it would be possible
to give Joe homeowner an easy way to get a dome shed up - and maybe
he'd go for a garage next - who knows, maybe the addition, or the
house...  To appeal to the general public, I too believe that we have
to make this easy for those not prone to experimenting with their
structures.  One nice feature of the connector idea is that you can
set the size of the dome using the strut lengths, using the same hubs,
as long as the frequency and dome type stays the same.  If the strut
connectors are free to bend as they are on some of the gazebo hubs,
they can be used in a variety of dome type. Although this might not be
simplicity itself with respect to hard panels, if one is using a
softside cover or screenhouse type arrangement, it would be a nice
feature.
    As to the verticle offset issue for struts and hubs, I'm not sure
I follow the thinking.  To amplify the problem, suppose I wanted to
join five 2x4's (pent center) with a single pin.  Even if we drill a
properly angled hole through the 1.5 inch thickness, we wind up
needing a pin that would be 7.5 inches long.  (Obviously this is an
extreme situation I'm creating for ths sake of illustration.)  The
problem would be that the compressive forces on the pin would tend to
twist the pin out of the preferred alignment.  We could "offset" the
struts so they are in the "same plane" using a bracket of sorts to
reduce the 7.5 inch pin down to something that concentrates the load
bearing portion of the pin into something more like an inch or so.
This reduces the tendency of the compressive forces to twist the pin,
and get us closer to something we would see in a starplate type
arrangement where there is much less tendency for the "pin" area to
yield to off-center forces.   Actually you see this to some extent
with the old conduit dome, where one stamps the tube ends flat, drills
a hole, and just joins with a bolt.  However, with smaller domes, the
offset at the pin is more than compensated for by the sheer strength
of the arrangement, and it works fine.  You don't really risk collapse
by having the pin twist and having one strut overrun the other.
    Unfortunately some of the servers are out at the moment, so I
can't look at the proposed hub designs.  However, if my example
reveals that we are all on the same page with respect to offset stuts,
'nuf said, but if I am still missing the point someplace, please
educate me - maybe someone has figured out something here that I've
overlooked.   The idea is to reduce the offset on the pin to as close
to zero as possible, so the compressive forces are in the same
veritical "ring" on the pin.

cheers  -Dan G.