Introduction

If you have an old glass with a top internal diameter of 79mm and an external diameter of 85mm, you are in great luck, because that means that you can make this Awesome Vacuum Chamber. The only thins you need more than the glass, is a 3D printer, a smooth print plate, a 60ml syringe, PETG and flexible filament.

Function

In the figure below is a cut-view of the 3D printed assembly, the black parts are printed in flexible filament (TPU85A), the grey parts are printed in PETG and they ensure the air moves in the correct paths, the green parts are also printed in PETG, and their main purpose is to act as enclosure.

Since this Vacuum chamber is driven by a syringe, there needs to be a mechanism ensuring that the syringe only pulls air out of the chamber without pumping air in again. which is why there are membranes. In the figure below is an illustration of the air path when the plunger in the syringe is pulled and air is sucked into the syringe, here the air is being sucked from inside the chamber, trough the bottom manifold and into the syringe, while the top membrane is closed due to negative pressure in the manifold.

When you then press the plunger down and the air is forced out the syringe, the bottom membrane is no closed due to the positive pressure in the membrane, which causes the top membrane to open and let the air out of the membrane. 

So as the plunger in the syringe is moved back and fourth, the air in the chamber(glass) is slowly pull out resulting in a negative pressure in the chamber. The negative pressure in the chamber can be illustrated by putting a small balloon with a bit of air in the chamber, once the pressure in the chamber gets negative, the balloon will increase in size, this can also be done with marshmallows.

Your pump will be a syringe, and this can be a syringe of any size, i used a 60ml syringe because that will displace a bigger volume of air faster, but the bigger the syringe the more force is also required to achieve a certain negative pressure. so the smaller the syringe means a lot of pumping but also big negative pressure, where big syringe means not so much pumping but also less negative pressure.

if you are able to measure with what force you are pulling the plunger in the syringe, you can also estimate how much negative pressure you have created in the chamber.

Printing

This is a difficult print, and will most likely cause problems to the untrained printer, but do not fear cause the worst thing that can happen is that you learn something new, so crack on!!

In the figure above all the parts are shown. Black=TPU85A, Green & Grey=PETG.

First of all it is important that the models are printed in their original orientation, so do not rotate anything, this is because the surfaces printed on the plate will be smooth, making it easier to seal the system correctly. This should all be printed on the smooth plate to ensure good sealing, and the TPU used should be as soft as possible for the sealing reasons as well.

if you by any change have some sheet rubber material laying around, it is also possible to cut membranes from that, as an alternative to printing them.

The TPU parts should be printed solid, to ensure that they are tight.

The PETG parts should be printed very strong as they will have to deal with a lot of force, furthermore it is wise to print them with at least 4 perimeters and set the seem position to random, as this will improve the change of the models being airtight.

Once the parts are printed simply put it together, when assembling the device, it is important that all the contact surfaces are smooth and clean otherwise it will not get tight. 

The parts called "Seal" or “membrane” are the TPU parts.

Otherwise there is nothing left to say than Good Luck & Happy Printing!!!