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Assembly

Three printed parts (base, funnel, filter support) become one manifold. This page covers putting them together; for printing them in the first place see printing.md, and for choosing which filter support and funnel variant to print see ../hardware/README.md.

Building the manifold

  1. Seat the filter support in the base. The support locates into the base through four bayonet pins, align, drop in, twist to lock.
  2. Place the membrane. Using disinfected forceps, lay the filter membrane gridded-side up on the filter support.
  3. Lock the funnel onto the base. The funnel's lower rim seats over the base's top connection and locks down over the membrane.
  4. Seal the membrane. The base's top brim carries two raised ridges, the "hills." Locking the funnel down clamps the membrane between these ridges and the funnel's inner slope, forming the seal that lets the syringe pull a vacuum through the membrane rather than around it. The outer of the two ridges also gives the forceps something to catch when picking the membrane up off the support in step 2.
  5. Connect the syringe. The 100 mL PVC syringe connects to the base's water tunnel. This joint is glued (UHU Hartkunststoff Spezialkleber) rather than a friction or thread fit, because the syringe stroke needs an airtight connection to pull a vacuum at all. The joint is made once during assembly and is not meant to be disconnected between uses.

A cross-section render of the membrane clamp, showing the base, membrane and funnel in distinct colours, is on the project site (site/public/renders/membrane-clamp.png).

Taking it apart

To remove the funnel after a filtration, squeeze the funnel's top rim inward rather than pulling straight up, this releases the clamp on the membrane without dragging the membrane off the filter support with it.

Retrofitting a commercial funnel

The base's top connection also accepts commercial Millipore Microfil funnels in place of the printed one; see "Retrofitting a commercial funnel" in ../hardware/README.md.