How to deal with Stepper Motor heat - 150 degrees F

Hi guys,

I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.

The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.

I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.

As always, I am open to any and all suggestions or ideas.

One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.

Chris