On Mon, Oct 22, 2012 at 1:09 PM, Edwin van den Oetelaar <oetelaar.automatiser...@gmail.com> wrote: > I think the problem is not there in the real world. > http://en.wikipedia.org/wiki/Gerber_format#RS-274X_extended_Gerber > > The output for production is at most accurate to a micro-meter or a > micro-inch. > Photo plotters and CNC drill machines are not as accurate in practice. > Furthermore, footprints are mostly defined on a grid, which is of a > known size (not in pico-meters accuracy but in milli-inch or > micro-meter) > > From the help-page of eagle ; > real u2mic(int n); > real u2mil(int n); > EAGLE stores all coordinate and size values as int values with a > resolution of 1/10000mm (0.1µ). The above unit conversion functions > can be used to convert these internal units to the desired measurement > units.
Is this a help page of Eagle 6? If so I'm wondering how can they state that conversion works flawlessly between impreial and metric even with a 1/64 mil grid. > For me personally the nano-meter is overkill already, more zero digits > behind the comma than before, we now limit the total board size > because of integer overflows. > > Hope this is useful for you. > > Have a good day, > Edwin van den Oetelaar > > On Mon, Oct 22, 2012 at 12:44 PM, László Monda <l...@monda.hu> wrote: >> 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> >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~kicad-developers >> Post to : kicad-developers@lists.launchpad.net >> Unsubscribe : https://launchpad.net/~kicad-developers >> More help : https://help.launchpad.net/ListHelp -- László Monda <http://monda.hu> _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : kicad-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
