: Hey Shawn
: So, yeah, I built the PVC pump. It didn't work right to start with because I
: used a bicycle inner tube for the inner tube bits.

Bike tube should work, but your tolerances might be a little tighter

: Then it didn't work
: right because my bottom disc wasn't sealing properly. Well... The second
: problem leads me to think that it might be easier or work better if the
: bottom disc was the diameter of the outside of the tube and just got glued
: on. Ok, ok, this removes some of the ability to field service the thing,
: but sheesh! How the heck do you make a disc the size of the ID of the
: pipe?

Sure!!! How about a flat-bottomed PVC end cap?

: Yeah - you wrote about maybe using a hole saw. But if I've gotta buy
: a hole saw, well, the whole venture is sure starting to get expensive!

Cut it bigger with a jigsaw and file it to shape.

: But, if you went to the trouble of getting a hole saw, you -could- make two
: discs the size of the ID and then sand just a wee bit off of one of them.
: You could then outfit both of them as described for the bottom one (inner
: tube to 1/8" less than the diameter, a bunch of holes) and maybe use
: the sanded one as the disc on the plunger... (Still a small problem of
: sealing...)

I think you really want the plunger rubber disc to be bigger than the diameter for a seal...however, drilling holes in that disc is a super idea, and would really improve flow. In fact, I'm going to do that to my own pumps...it never really was the "Baker" pump as much as a small "Dave Carnell" pump...but now it has to be the Shawn/Charles pump!!!

:If it worked right, it would probably be a bit less effort to
: use as well as being a little more effecient.

Yes, yes, yes!!

: (Not having asked ahead of time, I didn't put your link in the link box, but
: here it is for those who didn't already know it... )

Don't worry about asking--I've only put it on the internet in hopes that it might be helpful to others.

: ps: OT: I've just tried brewing my first maple ale... I could give a
: preliminary report when I go to bottle later in the week, but it had a
: pretty high initial sg so it shouldn't really be ready for months and
: months to come...

Sounds like a great ale to drink after a cold day's paddling!

shawn