kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Wed, Sep 03, 2014 at 10:22:03AM +0200, Maciej Sumiński wrote:
> I have never tried to order a T-shaped cut. What is the exact issue
> with that? I am wondering if it is still a real problem if the
> protruding part was within the Edge.Cuts line thickness (let's say 0.1
> mm).

The problem is not the T but the little 'hook' that it forms.

> Healing could be done another way. Instead of moving vertices, it
> could be better to add the missing segments. If they are no longer
> than a line thickness, then it is not noticeable to bare eye and
> should fix the manufacturing problem. User should be notified of such
> changes, so he could verify them.

That's exactly the problem I mentioned. Just like DRC on copper detects
features too small, DRC on milling detects features too small to be
machined reliably (typical board cutter is about 2mm, so any concavity
smaller that that can't be machined, also tolerance is ±0.1mm or worse).
It's actually harmless but some fabricator will have to fix by hand the
toolpath created by that 'tooth' (other will simply reject it). Smart
CAMs could of course just run over it and warn about unmanufacturability
of the exact toolpath.

Also usually the whole board would be panelized and edited for
ratbiting/scoring and that would be complicated by the 'added' vertices.

So either flag it or fix it without creating new vertices (that's why
I proposed to add it as a tool in the board cleanup).

-- 
Lorenzo Marcantonio
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