Kismet CNC Fabrication Tips · Lesson 1 of 12
Before you cut a DXF, there's one question worth asking: if the torch follows these lines, what metal will actually be left?
That's the difference between a drawing that looks good and a file that's ready for CNC plasma. A black silhouette on your screen can hide an opening that will fall out, two lines the torch will cut twice, or a detail too small for the cutting process.
We're starting this series with the basics: what to look for in a cut-ready file, what you need to check yourself, and why those checks matter once the design becomes steel.
Start with what you're actually cutting
Picture a metal sign with lettering and a few decorative cutouts. Some of the metal becomes the finished sign. The rest drops out as scrap. Your job is to make sure every piece that's supposed to stay is connected and every opening has a sensible cut path.
1. Will the pieces you want actually stay attached?
Look at the center of an O or an A. If you cut an uninterrupted opening all the way around it, that center becomes a loose piece. The same problem shows up in animal outlines, tree branches and intricate decorative artwork.
A bridge is a connection that keeps a piece attached to the rest of the sign. Its width matters. So does the material, cutting process and what happens to the part after it's cut. There isn't one magic minimum that works for everybody.
Measure narrow connections at the actual size you're going to cut. Shrinking the whole design also shrinks every bridge and opening. The plasma torch doesn't shrink along with your artwork.
2. Are the cut lines real, clean contours?
Your cutting software needs usable geometry—not just artwork that looks connected when it's filled black.
A closed path joins back to its starting point. An accidental open path leaves a gap. Two overlapping or duplicate lines might look like one line on the screen, then tell the machine to cut the same place twice.
Grouping objects doesn't fix either problem. A group just holds objects together for selection. The actual endpoints, overlaps and separate openings still need to be checked.
Don't worry about memorizing every Illustrator command today. We'll cover open paths, duplicate lines, joining and compound paths separately, with examples of what goes wrong.
3. Does your cutting process have room to work?
The DXF describes a line without physical width. Your plasma arc removes metal as it travels. That removed width is called kerf.
The torch also needs space to pierce and move onto the cut line. A small opening might look perfectly fine on the monitor but leave nowhere sensible for a lead-in. Tight details and narrow bridges can become trouble even when the vector geometry is perfectly clean.
You need to know your own machine and material rather than assume a file will behave identically on every setup. We'll start with kerf because it explains why a drawn dimension and a finished dimension aren't automatically the same thing.
4. Does the DXF import at the right size?
Check the overall width or another known measurement when you open the exported file in your cutting software. Units and export settings can change what comes in. Catch a scaling problem before you start inspecting every little feature.
Pay special attention if you resize a detailed design. It may need its bridges, holes or spacing redesigned—not simply scaled.
5. What does CAM actually tell the torch to do?
Your drawing isn't the final instruction to the machine. The toolpath is. CAM uses the contours, kerf value and cut choices to work out where the torch centerline will travel.
For example, if you're keeping the outside shape, the cut normally belongs in the scrap surrounding it. If you're cutting an internal hole, the cut belongs in the center you're removing. That's why you'll see the terms No Offset, Inside Offset and Outside Offset in this series.
Before cutting good steel, preview the finished toolpaths. Check for missing contours, unexpected extra cuts, offsets on the wrong side and lead-ins that don't fit. Then confirm the material and cutting settings for your machine. A clean DXF can't rescue an incorrect setup.
What we'll build on from here
Kerf and offset explain where the metal goes. Bridges, lead-ins and small holes explain which details can survive. Then we'll clean up the vector paths themselves and finish with a practical pre-cut checklist. Each lesson tackles one piece of the process; you don't need to learn it all at once.
Next, let's measure kerf
We'll keep this simple. Draw one square, make one No Offset cut, then measure the square and the opening left in the sheet. Two measurements from one cut will show you exactly what your torch removed.
Next: Plasma Kerf Explained: What It Is, Why It Matters, and How to Find Yours →