Hi,iam new here.for my bachelor thesis i have to produce 2 mechanical parts.the mechanican need the CAD files in .step or .iges.But my format is .dwg :(is there any (free) option to convert this ? sorry for the bad english.have a nice dayTom

Hello, I supose that we are talking about 3D.
For an direct export to .iges try :
File, export, --> .iges.
 
As far as I know, for a conversion towards a .step file you will have to go trough a Solidworks file ( or an other software if you have any ).
In Solidworks ( or an other ), open your 3D file with the good options ( mm, as a 3D model etc... ) and "save it as" --> .iges or .step ( you have the choise between diferent files ).
 
Before this, ask the person if it's OK with a .sat file ( that AutoCAD can make dirrectly by an "export to" ).
 
Please let me know if it helped or else not...philippe JOSEPH2012-10-29 13:29:40

Depending on what software you are using, will depend on what/how you can do this. If using a newer (2008 - 2013) Autodesk product there is no need for a different program.

If you are using AutoCAD (depending on the version), all you have to do is go to the upper left corner, select the big "A" and find export (on the left side) and export your file as the desired format.

If you are using Autodesk Inventor, you can go to the top left corner and select the big "I" and choose "Save Copy As" and then got to "Save as Type"(down at the bottom) click on the pull down and select your file type to save it as.

igesexport  - but some things may turn out a little differently than what you had originally drawn
 this is same as last post...DBARN2012-10-29 14:55:42

I have a solidwork file save as .igs I need to convert it to autocad 3d

AutoCAD directly opens both SolidWorks and IGES files. See:http://www.cadforum.cz/cadforum_en/formats.asp?fmtin=21&fmtout=1