I have some enclosed 75 hp motors and fans that I want to permanant instrument with accel's. Does anyone have a procedure on instrumenting motors? I am looking for where is the ideal place to drill the 1/4" 28 hole and not have to worry about damaging the motor. Or any better ideas?

We use 1/2" thick x 1" diameter metal pads with the hole drilled and tapped on one side. The diameter matches our accelerometers. The mounting surface has to be flat, clean, etc. I use a hand file or an air grinder with a 1-1/2" disk to grind a place flat to mount the pad.
I use Loctite 330 adhesive to glue the pad on.
One part is adhesive the other is a spray activator. Put adhesive on one surface, spray activator on the other surface, hold the pad for about 1 minute. Attach the accelerometer to the pad. I have been using this system for several years. If a pad/accelerometer gets knocked of, clean it up and glue it back on. No broken screws or housings with pieces broken off. Spare equipment can have the pads mounted ahead of time, when the spare is installed, the pads are there ready to go.

I'm sure there are many other ways to accomplish this. Everyone has there own preferencies. This is mine.

Goodluck
REJ

REJ gave a good discription for setting up existing motors that we have used with great success. For new motors we specify that the motors be tapped so we can directly mount the accels with lock tight and go from there. The motor guys are getting good at providing this modifcation for the PdM guys out there. I wouldn't be surprized if you see in the future motors/gearboxes and pumps tapped for PdM monitoring right from the factory. They supply thermocouples now why not vibration instruments?