I was having problems having the indented A through R showing up on my printer, so I remixed these in Blender. My printer nozzle is .5 mm - the new letters have a tolerance at least as fine as that. (.5 mm or smaller nozzle = okay).
Things remixed:
Letters are now extruded, not indented (allows better painting)
Re-centered the letters/numbers/pips
Printer Brand:
LulzBot
Printer:
Mini
Rafts:
No
Supports:
No
Resolution:
Layer height was .38
Notes:
With a smaller nozzle, you could probably have finer accuracy/smaller letters.
Avoid using a thicker shell than necessary! I was using a 1.5mm shell later on, and my printer had trouble with the numbers. (I'd recommend a shell width equal to your nozzle size.)
Remix Process in Blender
Step 1: Mesh > Clean up > Limited Dissolve in edit mode.
Step 2: Grabbed the face(s) of the indented letter along the Z-axis
Step 3: [Ugly] Expand the letters to be larger. Manual process, as scaling wasn't awesome for my purposes. (Grab a bunch of faces that would be going in one direction, then x/y to slide along the axis.)
Step 4: In wireframe mode, I'd select the faces of each different element (letter, number, pips) and re-center them.
Cura's layer mode was useful as a baseline, post-Blender, to see if the newly formed letter was going to print.
The user re-uploaded this model. The user is not the original author of the model. Imported from Thingiverse.