Allen,
My previous setup that I had to change to get the fan to fit into the window was black pipe. It seems like I spent a long time trying to get all of the leaks out. Never did. Finally just gave up and turned the air off at the compressor when ever I was not in the shop. Real pain in the neck. I tested the new setup for leaks by turning the air off at the compressor and it took 4 days for the pressure to drop below 20lbs. I'm happy with that.
Jason,
I built the platform for several reasons. First was to provide stability so that the foot print would about twice as big as the foot print for the feet that are built on the compressor. It seemed like the unit would be a tip hazard unless I drilled into the slab floor and anchored the unit. I really didn't want to drill into the slab. With the base, the compressor is very stable and does not have a tendency to tip at all. The other reason was to attempt to isolate the physical sound transmission into the rest of the house when the compressor is running. I really wanted specific vibration isolators but when I priced them I decided that I would just use rubber sheet that I found at my local hardware store. I cut holes into the rubber sheet and put that under the feet of the compressor. I also cut the rubber sheet and but it between the bolt washers that secure the compressor feet to platform. The platform is made from hardwood 3/4" plywood and 2x4 with a cross brace in the middle for strength. I put leveling feet into the 2x4. This allowed me to level the platform since the floor has a small slope to allow for water drainage (builders seem to think that people park cars in these garage areas). Under the leveling feet there is another sheet of rubber. I don't know how much difference this really makes since I never ran the compressor without the rubber sheets in place.