Why am I doing this?

Because I can - and it is hard to say no to pretty ladies with grand people-helping schemes. :-)

This will end up in the Better World Museum as a neighbor to the Garden One... thing.

Some day - skyway walkers will stop in and pluck some healthy plants to eat with their Cardigan doughnut.  ;-)

However, before then I will be able to offer you guys a ring gear (or the STL file) and a spring so you might take a whack at it yourself!

Or maybe you have another need for rotating something large?

Those gears are 50% infill (maybe doesn't need to be that dense) and takes 15 + hours.

There is a top cap-ring that goes with it (I'm printing out the first one of right now) - another 3.5 hrs.

So... now it's a month or so later and...

1) The pipe is perforated.

2)  The pipe is filled with coconut fiber

3) Tthere is a water pump in water

4) There is a hose up the middle to the top

5) There is a wonderful 'water diverter' at the top that perfectly distributes the water all around to fall almost exactly halfway between the inner and out pipes.

6) There is a 'pulse discharge' circuit that dumps a 'slowly accumulated charge' from a 3 FARAD-20V cap into the 12VDC water pump - when it's charged up enough (16V?)  to get some work done.

7) There are LIGHTS!

What there is NOT is that gear rotating it.... yet.

So what now?

   Supporting that pipe on three rollers.

I finally have some numbers to go with that goal ...

I dumped 6 gallons into the barrel-bottom.

It looks like there is maybe 2 gallons in there now after cycling 1 cup every 9 minutes (about 10 gal/day) to the top for a few days - I'm calling it 'stabilized'.

That means... 4 gal in the pipe.

That means... the pipe weighs at least 30 lbs.

That means my poor rollers are going to have 10lbs pressing on the tiny contact area (about 1/8" square?) where edge-of-pipe meets nylon roller.

That sort of equates to... (30/3) /  (1 / (8*8)) --> 640 psi.

It will work, but 'for how long' is unknown.

I have the rollers, I have a mounting scheme worked out, I have sporadically-spaced short-duration blocks of time to do it, so... stay tuned.