Hi all.  I recently purchased a set of BLI N&W H2a hopper cars with the intent of back-dating them to something resembling an HU. Based on what I know, H2a’s are identical to H2s, which were rebuilt HUs.  So I figure the car is as good as any for a starting point, from a dimensions point of view.  Back dating the three hoppers to four might be a problem, but I’m ignoring that minor detail for now.

One of the back-dating steps is removing the vertical side ribs - the HU had fewer side panels than their offspring. I’m considering doing that with my mill.  Here’s my ask: I’m looking for advice on an appropriate end mill cutter type for use on plastic. My limited experience with milling has been confined to aluminum and brass, and on projects where surface finish wasn’t a driving factor.

I suspect I would need four flute, relatively small diameter mill to reduce bite and the possibility of tearing?  Advice on that and other related guidance is greatly welcome.

Matt Goodman
Columbus Ohio US