delorie.com/archives/browse.cgi   search  
Mail Archives: geda-help/2017/04/20/12:46:09

X-Authentication-Warning: delorie.com: mail set sender to geda-help-bounces using -f
X-Recipient: geda-help AT delorie DOT com
Message-ID: <58F8E5B2.90503@xs4all.nl>
Date: Thu, 20 Apr 2017 18:45:38 +0200
From: "Bert Timmerman (bert DOT timmerman AT xs4all DOT nl) [via geda-help AT delorie DOT com]" <geda-help AT delorie DOT com>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.19) Gecko/20110429 Fedora/2.0.14-1.fc13 SeaMonkey/2.0.14
MIME-Version: 1.0
To: geda-help AT delorie DOT com
Subject: Re: [geda-help] g-code output
References: <1525952036 DOT 65314 DOT 1492659528690 DOT ref AT mail DOT yahoo DOT com> <1525952036 DOT 65314 DOT 1492659528690 AT mail DOT yahoo DOT com>
In-Reply-To: <1525952036.65314.1492659528690@mail.yahoo.com>
Reply-To: geda-help AT delorie DOT com

No Body (att80 AT att DOT net) [via geda-help AT delorie DOT com] wrote:
> Hi,
>
> I have looked at the g-code output that geda-pcb offers.  It appears 
> to provide code for what is called isolation milling which is what I 
> commonly see else where too.  Does anyone know how additional g-code 
> can be generated to remove additional/remaining copper from a board?  
> This type of milling might be typically called pocket milling.
>
> Thanks.
>
> Al
Hi,

As amechanical engineer (day job) I happen to have looked into the 
subject of pocket milling ;-)

Pocket milling: https://en.wikipedia.org/wiki/CNC_pocket_milling

Requires a (non copper) polyline (or polygon) on a (designated 
(routing)) outside layer to define the area to be pocket milled (inside 
milled, outside milled) in pcb.

Requires an algorithm to determine the required router minimum diameter, 
consider concave/convex curvatures, passing obstacles and bottle-necks 
and other quirks.

Requires an algorithm for the optimum number of tool changes (large 
areas with large diameter router, corners and stubs with a small 
diameter router bit).

Requires an algorithm for routing with the least router bit wear (cost 
function, Traveling Sales Person algorithm).

Possible candidates are "zig tool path", "zig-zag tool path" algorithms, 
or a number algorithms based on a set of offsets of the polyline 
"curvilinear tool path" or "contour parallel tool path", some Voronoi 
based algorithms exist, there are several solutions possible here, 
caveats are Self Intersecting Polylines (SIP), Open Polylines, non 
continuous polylines .... you get the idea.

Some algorithms give good results in detecting anomalies ... some are 
quite poor, YMMV.

On a scale of 0 (no-brainers) .. 10 (skunk worx, hard rocket science) 
for complexity, this is somewhere in the 11 region ;-)

Kind regards,

Bert Timmerman.

BTW: we could use someone with strong G-code fu for this one ;-)

- Raw text -


  webmaster     delorie software   privacy  
  Copyright © 2019   by DJ Delorie     Updated Jul 2019