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DXF scale or units?

Printed From: CAD Forum
Category: EN
Forum Name: AutoCAD
Forum Description: Discussion about AutoCAD and AutoCAD LT, viewers, DWG and DWF formats, Design Review, AutoCAD 360, add-ons
URL: https://www.cadforum.cz/forum_en/forum_posts.asp?TID=81
Printed Date: 01.Jun.2026 at 06:21


Topic: DXF scale or units?
Posted By: cdsdonham
Subject: DXF scale or units?
Date Posted: 02.Sep.2007 at 19:25
Hi all --

I'm writing my own program to generate a DXF file for a very specific need.  I can get the geometry into the DXF file, but when I load the file into autocad's design review, I'm having trouble with the scale or units on the drawing.

Can anyone point me at either documentation and/or an example of how to specify in the DXF file what the units or scale of the drawing is?  Generating the polylines was easy (with the help of a library).  There appears to be a bunch of header variables and I can't seem to get the right combination of $VARIABLES to get the scale set correctly.

Also, I'm using a random cad library I found on the web which appears to be a bit dated.  I need a C++ API under windows for generating the DXF file.  Does anyone have any good suggestions about what to use?  I tried autocad's free library, but it appears to generate DWF files not DXF or DWG which is what the CMC tool apparently needs.

Thanks.

Chris


Replies:
Posted By: Vladimir Michl
Date Posted: 03.Sep.2007 at 07:47
You normally don't need any scale for modelspace DWG or DXF files. The drawing just uses "units" (unitless) and scale is used just for plotting, dimensioning and paperspace (layouts).
Probably your CNC tool scales the imported DXF files for some reason. If so, you can generate all the coordinates scaled down or up.


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Vladimir Michl (moderator)
ARKANCE - https://arkance.world" rel="nofollow - https://arkance.world - Autodesk Platinum Partner


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