We also use AutoCAD (Mechanical Desktop) for generating assembly drawings. I
agree that AutoCAD can be painfully slow dealing with a drawing which
contains a Protel created PCB.
Although our current method leaves a lot to be desired it does help size and
I am currently doing the assembly on a test board which contains 150
capacitors, 2 DB9 connectors, 2 SMA connectors, 30 switches and 2 integrated
circuits. the board is 7" x 9" and contains center array of vias which is
approximately 8.5x3.5
What I have done is create a DXF then a DWG of the top, bottom and middle
routing layers. I went into each dwg in autocad and erased the poured ground
plane, leaving the outline. Then I erased all of the middle via array,
except the last row and column. This 'representation dwg' allows us to
create an assembly drawing which the Assembly Dept. can use. I then put
these 3 layers into an autocad PCB drawing which is used in the assembly.
We also use this technique because most of the PCBs which I design are not
test boards, but actually get assembled and put into modules which are the
final product. We do all of this as 3D solid models in the computer and
generate complete sets of assembly drawings and parts lists in AutoCAD.
So far this meets our needs, though it get easier each time the computers
get better.
Susan Scott

-----Original Message-----
Sent: Monday, April 02, 2001 11:20
Subject: [PEDA] Creating Assembly Drawings

I'm working to define our internal process to document boards for
 Specifically, I'm having a difficult time generating assembly drawings.  

After much discussion, we decided the best path is to use AutoCAD.  It
a great deal of flexibility to scale, rotate,  and position the details for 
improving communication with the production staff.  I use Gerber files 
converted to DXF  via Camtastic.

Here's the problem.  AutoCAD is dirt slow when it comes to redrawing the 
screen.  A simple two layer board takes seconds to redraw with only the 
silk-screen layer imported.  The entire layout in Protel or Camtastic is
quick to redraw.  It's killing the process.

1.)  Is there any way to improve the redraw speed in AutoCAD short of moving

from my P3, 600Mhz, 256M RAM to a faster computer?

2.) How do others generate documentation?

3.) Any other recommendations?

Thank you,
Steve Allen
Project Engineer
Manufacturing Services, Inc.

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