Frage HPGL shortcomings

Hi all - sometime back I highlighted the problems I was having importing HPGL files into Stepcraft software. The problem is that ALL circles when cut are undersize.

I believe I now know the answer! - I think its the ay HPGL files are produced - circles & curves are NOT output as curved lines, but polygons composed of short straight lines. Thus the cutter only touches the required diameter & the rest of the cut is INSIDE. The problem is worse with small diameter circles, since small circles, say, 3 mm are output as say, a 6 sided polygon. Thus the cutter only touches the full diameter 6 times -the rest of the cuts are straight lines INSIDE the circle.

Thus all circles are undersize. The problem reduces with large circles - but the effects are the same.
I overcome this easily by enlarging the drawn radius slightly - say, by 0.1mm on small diameters.
Don't know what the effect is on DXF files & their minimum resolution. On HPGL files, I believe it 1/40mm (0.025mm) - which also explains the phenomenon.

I use Stepcrafts own USB software which I find excellent for my use - 21/2D. It comes with many additional features like tool offset capability - which means I only have to upload my drawing files, set the tool dia & the software does the rest. Brilliant.