Adeel

Your NC file *.txt output is the Excellon file that they request, the 2:3,
2:4 etc is the degree of accuracy (i.e. the 3 and 4 refer to the number of
decimal places). This should match the file format that you have generated
your gerbers in. As to whether to output in metric or english that is
dependant on the machinery that your fab house uses. So long as you specify
what the data is that you have supplied they can convert it to what they
require.

The main reasoning for variation in the pad/trace to edge for routing/vee
score is that the router is a rotating bit and will cut adjacent to your
board outline and is highly accurate. (The amount of variation is only due
to runout in the router spindle only a few thou.) Whereas for Vee score you
are using something that is more like a rotary saw blade top and bottom of
the board. By doing this the width of the cut can vary due to the angle of
the cut, the depth of the cut and is also affected by any runout on the
blade. As such most fab shops want a little more space before they get to
the copper.

As for the routing method. There are two main types the first is individual
rout where the the boards are cut out as individual units with 8 to 10 mm
between them. The other is common rout this is where boards with a regular
pattern, generally rectangular or square with only the width of the router
bit between them (generally 2.4mm) this allows for a higher density
manufacturing panel.

Hope that this helps.

Ian Capps
----- Original Message -----
From: "Adeel Malik" <[EMAIL PROTECTED]>
To: "'Protel EDA Forum'" <[EMAIL PROTECTED]>
Sent: Monday, June 03, 2002 6:02 PM
Subject: [PEDA] Issues related to Excellon Format and Scoring


> Hi All,
>          Some FABs require that NC Drill data for PCB fabriaction should
be
> given to them in Excellon Format. In Protel we have 2:3,2:4, 2:5 in
Englich
> units and 4:2,4:3,4:4 in Metric Units. Can someone comment as to which of
> these formats supported by Protel correspond to Excellon Format (or Whats
> the definition of Excellon Format) ?.
>
> Secondly, some FABSs specify different distances between Pad/Trace to
Board
> Edge for 1) Routing Method 2) For V-Cutting (scoring). So whats the point
in
> specifying different distances and What does the Terms "Routing Method"
and
> "Scoring" refer to ?
>
> Regards,
>
> ADEEL MALIK
>

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