Shapelock - custom cylinder foot in 5 minutes
I’ve noticed a lot of widely varying methods for smooth the edge on a DIY pumping cylinder, and I wanted to throw my hat in the ring.
I pump with a gravel cylinder ($6 at Meijer, by the way) which comes with a notoriously sharp edge. It’s very thin-walled and painful to pump in without a foot on there. So, I was looking around the house, trying to McGyver myself something comfortable, and found something even better than I had hoped for - Shapelock plastic.
The manufacturer (shapelock.com) describes it as “modeling clay on steroids,” but that’s just stupid. New, it’s a bag or jar of tiny, white pellets. Dump them in a pot of boiling water, though, and they start to turn clear, then stick together, then be freely shapeable. Let it cool and the stuff is pretty solid. If you don’t like the shape, you can just throw it in the water again, and reshape to your heart’s desire.
So, what I did was:
-I wrapped a piece of lined paper around my cylinder, and marked where the paper overlapped itself, on one of the lines. This gave me a circumference measurement on the page. I also traced the bottom of my cylinder elsewhere on the paper to get a circle the size of the tube’s OD.
-Part two was heating enough Shapelock to do this thing. For this, I guessed. I had this stuff from another project, so it was already formed into parts. I just melted a couple together until it looked right.
-I pulled the silly-putty feeling stuff out of the pan (with tongs, don’t be stupid) and VERY quickly (because it’s still pretty warm) rolled it into a rope. Every so often, I’d lay that rope down on my paper to see if it was the right length - just a bit longer than the circumference I marked earlier.
-When my rope was long enough, I looped it into a circle about the diameter of my cylinder, according to my tracing. I laid that circle down, flattened it a bit with my thumbs, and then pressed the bottom of my cylinder into it.
-The ID of my Shapelock circle was encroaching too much on the inside of my cylinder, so I smooth the inside edge up towards the top of the tube.
After all that, what I ended up with was an air-tight, high-surface-area foot for my cylinder, and a very comfortable pumping experience. I suppose if I was brave and had some more time, I could have let the Shapelock cool JUST enough to be safe, and then inserted into the cylinder for a really customized fit. I don’t advocate that, though, as it sound VERY dangerous.
The Shapelock, by the way, comes in a big tub for $30 or something, or the little “free” sample bag I got for $5 shipping.