Several CAD/CAM programs support designs saved in Bentley System's MicroStation software (.dgn) and can edit or even export it to any of the other, suitable engineering formats. That should possibly include .jt files in JT Open CAD format. A good choice for this conversion may be one of the dedicated conversion tools, for example PolyTrans|CAD+DCC.
Convert MicroStation drawing to JT Open CAD 3D model format.
We found 2 software records in the database related to .dgn to .jt file format conversion.
Microsoft Windows software - convert dgn to jt on Windows
A feature rich 3D CAD software by Siemens
Convert from dgn file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned dgn to jt. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A 3D CAD translation softwate