Hi Bob, yeah fonts can be pretty challenging to fillet or chamfer because they often have a lot of sharp angles in them, and sometimes they can have kind of messy curve structures since they were originally designed for just making 2D text which is much much less finicky about stuff than things like a fillet calculation.

One thing you might try when you want to use a particular font is to create it as curves only initially, and then select those curves and turn on the control points with the Edit > Show pts command.

If the control points look pretty chaotic like with a zillion more points than you thought would really be needed, then that might be a fairly messy font. One thing that can help to clean up some things like that is the Rebuild command:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#rebuild

Also if you make a solid version of a font and its sides seem to be broken up into a lot more fragments than what would really be wanted, that may mean the font has little segments in it that are not quite smooth to one another, causing a lot of little faces to be created for the side walls part when it gets extruded. That's also not great for filleting as well. Running the Rebuild command on the curves before extruding them can also help to glue together curves that are fragmented into some smaller segments like that into longer segments which can then avoid making so many little faces on the side walls.

- Michael