Can't enter accurate dimensions in PCB view


#1

I’m creating a new PCB, and in the Inspector, I want to enter dimensions for the origin / location.

The app will let me enter 0.0 mm for the Y coordinate, but the X coordinate always jumps back to 0.059 mm / 0.002 in – not a huge inaccuracy but I’d like to understand why I can’t enter a true zero value for the X coordinate.

Align to Grid is turned off, and I’ve restarted the app after changing that pref just to be sure that it was applied.

I’m using Fritzing 0.9.2, just downloaded it and started diving in.


#2

I think this IS actually correct, the ‘line’ around the pcb is .059 mm / .2 in wide
so the outer corner of that line is dead-on the 0.0 position
and the PCB itself is then .059 mm offset.
apparently this is how SVG handles the origin

so if you set the origin at -0.059 then all should be ok


#3

Thanks uaneme, that makes sense but I would expect the Y axis origin to be the same. However I can type in 0.0mm for the Y origin and the value is accepted exactly as typed.


#4

Hmm.

On what OS is this?
I’m running 0.9.2b on Ubuntu 12.04 64 Bit in this case and there it appears to work as described above.
I’ll try it on a 32 bit box tomorrow aswell and see how that turns out


#5

I’m on Mac OS 10.11.2

Here’s a short video capture. I tried to type “0” into the X origin and it always changes back to 0.002 in. Then I noticed that the Y origin is also not acting as expected, I had not noticed this before because it was snapping to zero (the desired value) but as you can see I enter values of 0.001, 0.002, and 0.003 which all snap back to zero. Then when I try to enter 0.006 it snaps to 0.008 instead.

This video may not play inline, please view on Dropbox:

Hopefully this is just a newbie’s oversight of some obvious setting or feature. It seems like there’s a global precision setting but I can’t find any such thing.

Thanks for responding.


#6

I’m going to make a guess. I have the feeling that the metric and imperial grids are a grid-line-width misaligned.
the PCB dimensions are in metric with an outline around the size that you ser in the inspector.
BUT the origin is aligned to the Imperial origin so there is then a mismatch when rounding things down.

Smells a bit like crossplatform compatibillity details Windows Mac and Tux all have their own tiny quirks, throw metric and imperial madness in the mix and then i’m not surprised that stuff like this happens.
I hope the devs have a look at this, i also find it a bit weird. But for now i think we have to accept it

also, mac works in a different dpi screen resolution and i’m not sure what SVG uses as master ‘grid’ if pt or px are master then things are another degree more complicated …

Also if a part is designed in Inkscape, Illustrator or Coreldraw, I guess that also can have tiny mismatches.

Still i could be thinking way to hard and be 100% wrong about this


#7

I marked the thread as a “bug” instead of “beginner” because this doesn’t seem to be operator error on my part…


#8

I hope you still manage to do what you where trying to do. It’s easy to get lost in details.