During the time since I built the first Torchmate CNC plasma table in 1998 (I sold the Company in 2011), dozens of low cost CNC plasma tables have appeared on the market. Similarly, many people have built their own system. While there is a wealth of information out there on how to build a plasma table, I have seen little material on how to use them.
Your plasma cutter manufacturer will provide you with recommendations on cutting speed, air pressure, tip to work distance, etc. However it's kind of up to you as to how you come up with workable shapes to cut. The dxf files you find for sale on line are often the work of artists and others who are unfamiliar with "real world" CNC plasma cutting. The shapes may contain cutouts within cutouts, overlapping lines, lines to close together, and other flaws. It is best if you know how to create workable shapes from scratch.
Obiously inside shapes must be cut before the final outside piece falls out. The torch should travel in a counter-clockwise direction for inside shapes and clockwise for outside shapes. For intricate designs in 11 gauge steel, for example, a distance of approximately .150" should be maintained between cuts.
Your CNC driver software (the software that runs your machine) should have the ability to convert dxf file to G-code your machine understands. It should also automatically handle the cut sequence and torch travel direction requirements. While many low cost CNC plasma systems come with some kind of drawing software, it is often simplistic and lacking in features.
I put together a small web site that goes into detail about how to create shapes that will execute satisfactorily. These can be anything from simple suspension brackets and motor mounts to complex metal art. You will find nothing for sale there! This is intended as free advice to fellow car building enthusiasts. A link to the site is here: https://cncplasmadesign.com
A few examples of shapes cut using this technique:
