Originally Posted by Penis1986
Thanks Rootsnatty for the homemade water pump instructions, but who knows how mine would turn out if I made it myself.
It is so simple. No gluing or hardware, you just have to make two cuts on a length of tubing with scissors, and they don’t even have to be precise. Seriously impossible to screw up. Just follow the pictures I posted in that link if you decide to do it.
As to the cylinder, I would get a thickwall, they are the best. They are the more pricey ones you will find though. Pumptoys would be the next best, but they are still pretty expensive. Then you have the cheap, mass produced ones like LeLuv and SizeMatters. They are cheap and would work just fine for a first pump setup.
Get a cylinder that is at least an inch longer than your BPEL, although I would go two inches or more to be safe, and then you have to figure out the diameter. Take your erect girth and divide it by pi (3.14) and then round that number up to the nearest quarter inch. So if you came up with 1.69 that would round to 1.75. That would be a tube used for very fast packing, so primarily for length work. If you want to focus on girth, you would want to go bigger by another quarter inch. So using the same 1.69 from your calculation, that would come out to 2” to allow for girth expansion.
If that math and explanation didn’t make sense, tell me your mid-shaft erect girth and bone-pressed erect length and I will tell you what size cylinder you need.
And, by the way, these cylinders I’m talking about are the same clear acrylic ones you would use for air pumping.
Roots