Wednesday, February 3, 2010

Cheap and Indestructible Airbrush Cabinet

When I was fifteen years old I worked for Piedmont Division’s Dave Muller in his hobby shop and spent most of my time painting locomotives and cars.  His airbrush booth was small and lacked both ventilation and proper filtering.  Being young and broke I had to build my dream airbrush booth out of materials I had around the house.  What I build is still being used today and has seen over 1,000 trains pass through.  Here’s how to build a cheap and indestructible airbrush cabinet.

The cabinet rests on a home-made 2 x 4 stand.  You can also sit it on a table, or on saw horses.  You don’t have to spend a lot of money to have a good cabinet.  Click on photo to enlarge.

The benefits of this airbrush cabinet are many.  First, it is very strong and can take a beating.  Most of the galvanized metal cabinets will dent and bend, and the plastic cabinets warp and disintegrate.  Secondly, this cabinet has both incandescent and fluorescent lighting fixtures so that you can paint your model to appear color-correct under the proper lighting.  The third feature is the dual exhaust fans that allow you the proper blend of air current and filtration.  Solvent based paints require more air current and fume removal, where as water-based paint pigments will move around in the heavy air currents.  A forth reason to build your own is cost.  You can build one for a fraction of the cost of a hobby shop model using parts that you can find around the house. The fifth and most important benefit is that you can build it to the size you need.  Most over-the-counter spray booths are tiny and don’t give you enough room to work, especially with large models. 

The opening in the front of the cabinet can be as tall and as wide as you want to make it.  Think about what would be the largest object you would ever paint, and then add six inches to either side.

Construction of the cabinet consists of 2” x 2” and 1” x 4” board stock, some old barn siding plywood, and some ¼ inch hardwood and Masonite.  Use what you have laying around.  There is no need to make it pretty, just make it work!  Using the diagram, correct the dimensions to your desired size.  I cut my 2 x 2 stock to 29 inches and using the plywood outside, made a simple box.  Using the hardboard, I made the internal box for the bottom and left and right sides.  After ripping some 2 x 2’s to 1 x 2’s I made a simple frame to hold a 16” x 20” furnace filter.  Try to use the same filters that you use in your house if you can so you don’t have to buy anything.  Fix the frame so that the filter drops in from the top.

The glass sits on top of the wood and is sealed with caulk.  All other openings are sealed with sheet foam to give the fans the best draw.

The filter drops in from the top, then is sealed with some old foam packing that I found.  This keeps the air flow moving into the fans and keeps dangerous flammable fumes out of the lighting system.  Using some 1x4’s I made a frame for the top that holds the sheet of ½ plywood to which is attached the lighting.  Using the wiring diagram, mount the fixtures and run the wiring in between the outer wall and the inner painting chamber.   Be sure to leave enough room between the lights and the paint chamber for the glass.

You can now cut out the front opening of the painting chamber, and even cut a space for a drawer and a removable electrical switch panel.

I chose to make my wiring panel removable from the front in case I wanted to modify it or if I spilled paint on the switches and they had to be replaced.  The drawer was something I found in an old cabinet and the hole was cut to fit.  Since it is very small it did not need runners or guides.  It is just enough to hold my Aztec case and the extra bottles. 

Here you can see the twin fan exhaust ports

Slip on the dryer vent hoses and you are ready to paint.

The twin fans are wired separately in order to control air flow.  You can turn on either or both as you wish.  IMPORTANT: make sure the fans are brushless AC fans.  You don’t want an explosion while using flammable paints.  Mine are 4 inch fans from an old computer case.  I cut two circles out of the back of the box and mounted them there.  Over the fan I put two galvanized metal heat duct reducers that I bought for a buck each at a hardware store.  Using duct tape I sealed the connection.  I found some used clothes dryer vent hose that I attach to the hoses on both ports when needed and drop them out a nearby window for external ventilation.  They are not used for water-based paints, only solvents or when something is drying and I need air current to the outside. Don’t use too much hose as you don’t want the fumes to gather in the hose causing a hazard.  Use just enough to get the vapors outside.

The last step is to mount a sheet of cut glass over the top of the paint chamber, just under the lights.  I sealed the glass with caulk so that fumes would not creep into the electrical circuitry.  After this you can use the caulk to seal all crevices in the paint chamber and around the filter housing.  Your last step is to paint the inside paint chamber white so that it better reflects the light.  The glass above can be cleaned with a cloth and solvent if necessary.

Feel free to customize your design as you wish.  Just keep in mind that if you are using solvent paints that you don’t want any fumes in the electrical portion of the paint booth and you want to draw them away from your face as quickly as possible.  My estimate is that you can build this unit for about $75 or less depending on what resources you already have.  An old lamp is a good source for incandescent lights.  Fluorescent fixtures are $9 each at discount stores.  The switches that I used were from an old computer system and the wire was a broken extension cord.  Replace the filter once a year and keep the glass in the paint chamber clean.  Be safe and enjoy your new airbrush cabinet, as I have enjoyed mine for 23 years.

Ed Note: I wrote this back in 2000.  I just happened to see this airbrush cabinet again a few months ago.  I gave it to a friend when I built my new shop (and a bigger cabinet) and its still in use!

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