The kinds of small blowers I use are on the scale of palm-sized, AC
induction motor (no brushes to wear out) with outlet ports of about 1.25 to
2", speed approximately 3,000 RPM, wheel size 2-3" diameter and 10-20 CFM or
thereabout.

They're quiet, compact (so they can be mounted almost anywhere) and are
essentially trouble-free if cleaned occassionally and oiled with about 4
drops of oil per year.

Examples
http://www.grainger.com/Grainger/items/1TDN2

http://www.electricmotorwarehouse.co.../50747D600.jpg

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Gerald Miller" wrote in message
...
On Fri, 18 Jul 2008 11:07:26 -0400, "Wild_Bill"
wrote:

You might try to find a small centrifugal blower to establish some
positive
pressure in airflow, which can be directed into one end of the motor (with
some flexible tubing).

Fans don't push much air when a restriction is encountered (the interior
of
the motor case, or being piped to another location).

A small AC motor blower that doesn't have the blower motor in the air
intake
stream, so as to not add heat to the cooling air, will potentially provide
years of service with only some routine cleaning to remove dust.

Dayton, among other manufacturers, make small blowers that will be
well-suited for the purpose of cooling small motors.

The only additional feature that one of these small blowers might need,
would be to add a screened cover for the air intake to reduce the chances
that big pieces of debris from entering the intake.

Second hand range hoods are often replaced rather than cleaned up, and
can be picked up at the curb or bought for a couple bucks at yard
sales.
Gerry :-)}
London, Canada