I received an older Nespresso machine that would not pump water from the reservoir. I found out that this is not an uncommon problem when air enters the pump. I found a few mediocre solutions to force water in and air out, so decided to make this primer to have a more reliable and elegant solution.

I printed the seal with TPU, used a PLA backer that I glued to the seal to make it more rigid and used a cylindrical plunger to force water through the tubing and pump.

There is not much clearance between the plunger and the backer, so I had to smooth them out with some sandpaper. The seal has a small lip to seal against the plunger.

I was able to generate much more water pressure using this than other methods I tried and it was a lot less messy. (It turns out there is something else wrong with my machine, so was not able to get it to work.)

I printed the TPU seal with 8 bottom layers to provide some stiffness to the wiper portion of it. 4 perimeters to maintain some strength and I used 20% rectilinear infill.