OVAL OBLONG DRILL SLOT NC-ROUTE

Hi, 

I am trying to find a way for producing oblong drill holes. Even if I design an oblong pad and then create the artwork files, i cant read the nc-route file in CAM350 and oblong drills dont apeear on drill layer file(.drl). I exported OBD++ file but I need to obtain .art files for PCB house. Is there a way to produce oval drills or convert OBD++ files into .art files?

Thanks in advance.