Quote from: DreamThinkBuild on October 15, 2012, 07:37:14 PM
I just started this project and this is my third printed cylinder. From my experiments it take very little energy to push the lever with the weight aiding. Like all gravity devices I need to build bigger more mass. So far my designs have been iterative I've been fixing issues as I come across them. I can tell you why this 3rd version will not work and working on a 4th larger version so I can get a 2" sphere with a lighter weight printed lever...

Hi DTB,

Very nice construction.  I think it is great that you are doing a quality build of your device.  I suspect you are learning a lot about the issues involved and increasing your skills.  It does not matter if your device is O/U or not.  All that matters is that you are building a device and learning about the principles involved. 

Ignore anyone who dissuades you from dreaming and trying out different ideas.  Learn for yourself by doing.  Just don't fall in love with an idea so that you fail to learn the objective truth about it.  If your operating principle is wrong, then learn about that too.  Even an experiment that fails to achieve the original goal can have a useful result.  The post-it note glue was a dismal failure of an experiment to make a strong adhesive.  Penicillin was discovered from a failed experiment.  Objective powers of observation and dreaming about the possibilities are all that is required for useful ideas.

~Dennis

I now do not think I have a leak in my test system.  I believe I was pushing the system too close to the maximum or "ideal" lift and witnessing a water transfer phenomenon caused by my crappy build. 

In all ZEDs, while trying to stroke up with the absolute maximum lift mass the water in the system will rise to the very edge of the retaining walls.  If you add input water at any appreciable rate to the Pod chamber at that condition you will cause a wave of pressure differential that, while it tries to stabilize, will cause some of that water to spill over.  This causes air in the next passage to also burp up under the next Riser wall and a cascade of water and air resettlement occurs from the inner chambers towards the outer chambers of the ZED.  This is "blowing skirts" and normally a fairly violent and obvious event.

However, in the case of a poor construction with not very cylindrical members you may have the condition where the walls of the Pod/Risers and Retainer Walls come close or into contact.  Capillary action causes water to rise up around these close contact areas and "wick" or "weep" over the retainer wall tops in a very slow and gentle manner possibly.  So it is a sloooooow skirt blow scenario that does not evidence itself with the usually expected violent skirt blow activity.  Instead, you end up with extra water in the outside annulus and a slowly decreasing lift potential that leads you to think you have a leak.  At least that is my current theory.

I lowered my lift mass from ~1153g down to exactly ~1000g to see if this corrected the problems I was having that lead me to believe I had a leak in the system.  So far, so good.  Further testing for stability is, of course, needed.  But I think the leak (like the cake) was a lie.

M.

 
Told you that you'd figure it out !

PS - same thing happens in (as others have said) "better" builds too.....
Can't tell you how many hours I've spent, even now with the ability to add / remove air or water where I think it's needed (or not) and have still not come up with the combination that will leave margin top and bottom for 66% of IDEAL in a managed .750 lift in both loaded and unloaded conditions.

I'll think I'm close... and then I'll see a meniscus form at either a top or bottom of this partition or that..... and try a different combination,,, or as you said, VIOLENTLY blow a skirt.

Interesting - but frustrating some times too.

Been there done that
Dale

Dale,

I wonder if .750 in. is too much to ask for in your build?  At least with only three layers (1 Pod, 2 Risers)?  In other words, I think you may be at the limit of your system also.  So you need to change one of four variables:  lift distance, lift height (above the "floor"), lift mass, or number of layers.

For me at least, stroke range and the height of that stroke range above the absolute minimum level of my Pod/Riser system were very critically linked to the "ideal" lift mass.  So maybe back off of one of those parameters a bit and see if you gain stability?

My belief is that you will gain a greater maximum level in at least one of those parameters as you continue to add layers.  JMHO.

Thanks for the support.

M.

So tomorrow is the big day 
can Wayne keep his promise this time.