Showing and printing diamond holes instead of round holes.
My designs have round holes, but when exported to STL, then imported into Repetier Host to print, the round holes show as diamonds, and are printed as diamonds.
Why would this be, and how to fix it?
This is a problem in your CAD software. When exporting STL all faces get discretized to triangles. Normally tehre is a setting to define how precise to follow curves. The more precise, the more triangles will be generated making them follow circles more exactly. So in your case 360° get converted in 4 segments => diamond. 8 segments would already look better and 32 would be quite good for most. Do not make them too small as that gives new problems like to small moves, big files.
Issue solved. Strange as these options were not selected in the past, and the prints came out fine.
These issues had to be selected in Alibre Design - STL output options
It would help if we could post images here.