kicad-developers team mailing list archive

[László Monda <laci@xxxxxxxx>]

Hi List,

http://www.cadsoftusa.com/eagle-pcb-design-software/new-in-v6/ states
that "Work with flawless conversions between mm and inches through
increased internal resolution (allows grids of 1/4, 1/8, 1/16,1/32 and
1/64 mil)".

Doing a little math it turns out that:

1/4 mil = 0.006 35 mm
1/8 mil = 0.003 175 mm
(1 nm = 0.000 001 mm)
1/16 mil = 0.001 587 5 mm
1/32 mil = 0.000 793 75 mm
1/64 mil = 0.000 396 875 mm
(1 pm = 0.000 000 001 mm)

This worries me because given the vast hobbyist userbase of Eagle it'd
be tremendously useful for KiCad to be able to import Eagle files
eventually *without* loosing any accuracy.  According to the above
values KiCad will retain precision up to 1/8 mil but not below.

I assume that nanometre resolution has been choosen because whoever
was in charge thought that it should be precise enough.  It's surely
accurate enough to manufacture anything but conversion problems can
arise.  I for one used KiCad from the pre-nanometre era and specified
values like 8.645 mm which got rounded to the closest available value.
 You may say that it's not a big deal but it is very disturbing and
it's certainly not something that one expects from a CAD software.

As absurd as it might seem only picometres would be small enough to
provide the needed resolution to not loose accuracy.

Please let me know what you think.

PS: By the way, just for historical reasons what was the resolution of
KiCad before the nanometre era?

Thanks.

-- 
László Monda <http://monda.hu>