Richard H. Siderits MD
Christoper Sereni MSIII
Varun Singh - Investigational Pathology Team
Removing bubbles, when you're making blanks to be used for machining plastic parts or casting models from Room Temperature Vulcanization (RTV) silicone rubber is an important step. The bubbles leave behind void spaces that can spoil an otherwise flawless model or part.
A "degassing apparatus" or Vacuum "Desgasser" takes bubbles out of plastic resin or silicone rubber, before it sets. Commercial degassers can be expensive.
This project shows you how to make a small vacuum degassing apparatus for under 20 dollars.
The only thing that you need to use the apparatus is a standard air compressor.
Step 1: Parts List:
2. Semi-rigid plastic hose and air-hose connectors - from the local hardware store (4 dollars).
3. Venturi-type vacuum pump* - from Harbor Freight (12 dollars).
4. Hot glue gun.
*Vacuum Pump specifications: A Venturi-type vacuum pump is connected to a compressor to supply the airflow that creates the vacuum.
Note: Air-Vacuum pump: Includes 1/2" ACME (R134a) connector. Vacuum level: 28.3" of mercury at sea level; Air consumption: 4.2 CFM; Air inlet: 1/4 NPT; Overall dimensions: 8-3/8" L x 5" W x 6-1/2" H
Weight: 1.75 lbs.
Step 2: Making the Vacuum Chamber: "Dollar Store Style"
The short segment of hose has to be rigid enough so that it won't collapse under the vacuum. The quick connect for the other end is not necessary but you can get it at any hardware store. The threaded end is only threaded on one end, the other end of the connector has a bayonet tip that goes into the tube.