It looks like you're new here. If you want to get involved, click one of these buttons!
Just a heads up for anyone else who may stumble across this issue, as I've spent hours trying to figure out why MeshCAM keeps crashing when importing my Bricscad-exported STL files.
When exporting your 3D models in STL, to import into MeshCAM, you must export as ASCII text files, not binary files. Any files you export via File->Export->Lithography(*.stl) will be in binary form, and will not work in MeshCAM (MeshCAM will crash on import (at least it did for me)).
To export to STL in ASCII text form, you must run the STLOUT command (see https://www.bricsys.com/bricscad/help/ru_KZ/CurVer/CmdRef/index.html?page=source/S/StlOut.htm). After running that command and selecting the solids to export, you will be asked "Create binary STL file?", type "No". This will result in your models being exported as ASCII text STL files, instead of binary, which you should be able to import into MeshCAM without any problems.
Hope this helps!