How do you prevent the aluminum housing vintage power tools from getting so hot that you can't handling them after just a few minutes of uses?
Brian-

check the wiring and brushes... something might be loose  or going bad.   it shouldnt be getting that hot.

I'll look in to that..

Also check quantity and condition of lubricant in gearbox, if present on your tool.  Some old greases turn into a stiff gel that increases drag, and reduces lubrication at the same time.  Also: make sure that you're getting full voltage at our outlet (under load, preferably); when I moved into this house, everything was 14-2 (#14 AWG, 2 wires, no ground) and a few 16-2, and anything on a longish run couldn't handle my larger motors.  Radial arm saw could be run for 3 - 4 minutes before popping the safety cutout (thermal device, resettable).  After I ran 12-2 W/G (2 wires, #12 AWG, with ground), I could run it for hours without a problem.  Before I rewired, I couldn't even START my bench grinder in the barn unless I shut off the lights, walked to the grinder and started it, then back to turn lights on, and tried to work without loading the grinder much, or it would shut itself AND the lights down.  Problem was made worse by the fact that this is the LAST house on the line from the power company; across the road to the east everything is fed from a different source.  I once saw 86 volts on my "110" line!

Thanks Ron, I will look into that...
Brian-

Ditto,
Everything ron said, and a second on brushes.

Brushes are *really* important on small motors,
some of the current that goes through the brushes is used to counter the currents in the field windings, when the brushes are bad this evergy is converted into arcing, and the current in the field windings skyrockets...

Have a close look at the commutator when you are servicing the brushes.
Make sure its not worn enough to make a lip that doesn't let the brushes seat all the way.
A fine tooth file will fix this.

  The little copper plates should be smooth and full width. Black color is not very important, but wearing at one side means the motor is not long for the world. You can clean it up some and get more mileage out of it, but a commutator that is wearing away, especially on one side, means the armature windings are leaking and due to either short out or fly apart fairly soon.   
Armatures are often available though. I have bought 35 year old Sears armatures right off the warehouse shelf. Milwaukee still has practically everything.
  yours Scott

Thanks for all of the info, with lock I will be able to get it running like new...
Brian-

Another thing to check !   How clean is it internally ?    Sawdust and crud are big time problems and act like insulation and prevent heat escape.  Dirty?  blow it out with clean dry compressed air.