How to Build a Paint Dryer
by Chuck Davenport
[Ed. note: This article was originally published in the
November/December 1994 issue of the IPMS Journal. Chuck has
given permission to reproduce it here. This article is just a taste
of what you get in the excellent magazine of the IPMS/USA. If you're
not a member, perhaps you might consider joining. Check out the IPMS
web site at: http://www.ipmsusa.org/]
...Apply decal set and let dry for a day...spray on four wet coats of
paint and allow the paint to cure for a week... Forget this drill. I
want to complete a model in less time than it took to paint the
Sistine Chapel, but everything takes so long to dry or cure. Not so,
said Pat Covert who related that fellow car modeler Bob Downey from
Atlanta was using a food dehydrator to drastically reduce drying times
-- from weeks to days (ed. note: even hours) in some cases.
Remembering a similar concept described in FSM I decided to raid the
spare parts bin (John Noack will tell you I never throw anything away)
and improve on the basic concept. Dehydrators work on the principle
of heat-generated convection currents. I decided to build a
forced-air device. The dryer sits to the right of my table/spray
booth (photo 1). The heart of the system
(photo 2) is a homemade heater core
attached to a polyethylene storage container that I purchased at
Wal-Mart for $5.
Figure 1 - General Assembly
The heater core is thin sheet aluminum 10" x 12" x 8 1/2" (totally
arbitrary dimensions that can be altered to suit your needs)
pop-riveted together using a Wal-Mart brand hand riveter. Nothing
fancier than tin snips and a couple of clamps was required to cut and
bend the aluminum. The top and bottom are 1/4" masonite with 3" holes
drilled for air travel. Heat is supplied by a 100 watt bulb mounted
on a $0.96 bracket, again, purchased at Wal-Mart (photo 2). A hand-formed sheet aluminum
manifold distributes heat and protects the upper sheet of masonite
from burning (photo 2). Air is forced with
a computer cabinet circulating fan connected to a switch (both from
the spares box) (photo 2). Figure 2
illustrates the wiring diagram.
Figure 2 - Wiring diagram
Air conditioner filter foam attached to the base with Elmer's glue, mounted to the fan, and fastened to the polyethylen box prevent dust from marring the finish (photos 2 and 4).
The top of the box was modified to control airflow and, therefore,
temperature by drilling a 1 1/2" diameter hole and capping it with a
sheet aluminum vent pop-riveted to the top, off-center from the hole
(photo 5). Figure 3 details the
Figure 3 - Exhaust vent
Photo 6 details a 3/4" plywood adapter
(with a hole cut to the size of the fan) that separates the heater
core from the box. Since the bottom of the box was manufactured with
molded-in flanges for strength and rigidity, the adapter joins the box
and heater core providing an airtight fit. I opted for the biggest
box I could find to allow maximum flexibility. But this forced me to
mount the box off-center relative to the core. Photo 7 shows additional 3/4" ply "shims" to
support and balance the remainder of the box on the heater core.
The final detail is to ensure adequate air flow through the vent holes. Accomplish this with rubber or wooden spacers attached to the bottom of the core (Photo 3). Find suitable items at Wal-Mart in the hardware section.
With a 100 watt bulb, the box reaches 92 degrees in 15 minutes.
Decals are dry and ready for subsequent work in under 20 minutes.
Model Master and Pactra enamels are dry in one hour. A Pat Covert
eight coat supergloss finish using Testors spray enamels is ready for
polishing in 24 hours (a far cry from his recommended 10 days). I
have used this dryer for four months and IT WORKS! The box does not overheat or melt. I frequently leave mine on overnight and throughout the next day. Just remember to route the electrical wiring clear of the light bulb (Photo 8).
In addition, before you walk off and leave yours on... test it to see
if it performs according to your expectations.
I spent about five hours constructing my dryer. John Noack and I
built one for him, too. You might try 1/4" plywood or plexiglass for
the heater core if sheet aluminum is unavailable. I would also steer
away from the use of a hot plate as a heat source. It may generate
too much heat. Good luck!
Charles T. Davenport