I've had an issue loading certain DXF files with splines properly. It seems that QCAD is borking up the interpretation of the splines resulting in 'wave-y' lines. I have loaded the same DXF into other CAD apps (such as ViaCAD) and they load just fine. If it helps, it seems all of the splines in question are control point splines.
Here is the DXF loaded in QCAD:
Note the rounded gear teeth, the skewed boxes around the text and the squared 'O's and circle surrounding the keyway.
Here is the same DXF loaded (correctly) in ViaCAD:
The DXF itself is from the 'Graphics for rotarians' website under 'Logos for architechual (sic) and contour cutting'. Googling 'Rotary DXF' gives the page as the first result. If the forum will allow me, here is a link to the file (just remove the spaces):http://www.graphics-for-rotarians.org/g ... _wheel.DXF