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Mail Archives: geda-user/2018/02/09/04:47:39

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To: geda-user AT delorie DOT com
From: "Richard Rasker (rasker AT linetec DOT nl) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
Subject: [geda-user] Another PCB grid step question
Message-ID: <c3aa1897-3806-3f72-feef-85551a63c2db@linetec.nl>
Date: Fri, 9 Feb 2018 10:46:25 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
Thunderbird/52.6.0
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Reply-To: geda-user AT delorie DOT com

Hello,

Recently, I submitted a bug report about PCB messing up metric and 
imperial step sizes when increasing/decreasing grid size, line size 
etcetera after start-up. (And pcb-rnd does this wrong even after 
selecting all metric sizes and steps).

However, there's one other thing with grid steps in particular that I 
wondered about: the actual step sizes.

Isn't it far more logical to adopt the logarithm-based step scheme that 
is ubiquitous wherever scaling takes place, so 1 - 2 - 5 - 10 - 20 - 50 
etcetera?

I myself predominantly work in a 0.1 mm or 0.05 mm grid, with occasional 
excursions to 0.5 mm. For this reason, I have my step size fixed at 0.05 
mm. If I want to go from 0.1 to 0.5, I have to hit the G key 8 times, or 
even 18 times to get at 1 mm (or take the scenic route through the menus).

In the many years that I worked with PCB, I never even once needed weird 
grid sizes such as 0.35 or 0.8 or 0.95 mm. Are these grid sizes actually 
used? Yes, I appreciate that, for instance, 0.65 mm can be useful when 
creating certain SMD footprints, but even that would only be handy for 
the chip pin pitch in one row. And even then, simply using 0.05 and just 
counting along from a reference point is often quicker.

Any thoughts on this?

Best regards,

Richard

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