On Tue, 27 Mar 2007 19:09:36 +0100, Adrian
wrote:

Now, since we are thinking along the same lines, you could ask a friendly
local engineering shop to thread the base of the existing bottle and add a
suitable connector for a feed from a larger "Pb" sized one.
Alternatively a side mounted adapter would work if welded on.
Also if you can remove the top valve you could possibly have a tail attached
to allow connection to a larger bottle.

Ah - I see where you're going with this...

I would be tempted to go for this approach.

Any thoughts about refilling the Sodastream cylinders from a larger
CO2 bottle ?? Wonder if that's feasible / safe / worth doing ??

as an idea of price. I've bought a pub co2 bottle for my mig welder
(from a welding shop). It cost about £45 for a full bottle and all the
required regulators and pipework (more regulators than you probably
need since i can adjust the flow rate and i dont think a sodastream
would need to - you can possibly just get away with the on/off tap
built into the top of the gas bottle).
It now costs me £12.50 to get the bottle refilled with 4.5kg or so of
gas.