I bought a bench-top combo belt/disc sander @Sears. My intention was to speed the annoying process of sanding the draft angles from DPM structure walls, you know on the bottoms and where the sidewalls attach to the fronts/back.
I figured this would also be a good tool to use in lowering the by then hundreds of MT cars. I figured while doing this, I'd remove the pizza cutters, spray bomb an Oxide Primer on the sideframes while the axles were removed and replace w/ MT low profile axles.
The Oxide Primer gave a good tooth for further weathering.
I did about 10 cars per weeknight for a few weeks.
I set up a good light over the disc part of the sander, used the included aluminum table to support the underframe, strapped on my Optivisor and set to work. After doing several cars prior to this with just files, I new how much metal I wanted to remove. It really became a pretty fast process and before I new it I had done almost 400 cars. I used a digital caliper at first just to make sure I was accurate enough but it wasn't necessary after the first few.
This method was only done on cars with full length underframes like Boxcars and Reefers, though I did use it on open hoppers as well.
All of my Gondolas and Flatcars had the metal frames removed to just behind the bolsters. I marked the locations of the holes where the pins attach before removing the underframe with a pencil.
I then fashioned new bolsters out of Evergreen strip Styrene. (I believe .125 x .188)
To do this, I'd take a strip, measure out an appropriate width for a bolster with a single edged razor and a scale ruler in multiples on a strip, drill the necessary diameter holes for the MT pins on the strip so you'd have a bunch of holes on an un-cut strip. Then you just complete the cuts where your marks are to net the individual bolsters. I then filed the two corners at the front of the bolster to allow for truck swing and glue them to the Gon or Flatcar bodies where my marked locations are. This process also requires some scooping of the remaining frame to allow for the clearance of the wheelsets. I use a Dremel and a Diamond Carbide burr to do this.
I think that explains it all pretty well. Let me know if you have any other questions.