I am part of a student engineering team and we are working on designing a CNC Plasma Tube Cutting machine that will cope thin-walled chromoly tubing, and also mark the tubes with bend lines/guides so that they can be bent afterwards in our tube bender. We have a couple of ideas that we are looking at incorporating to reduce the total size and cost of the machine (as it will only be used for ~2 months a year, and have to be stored in our small space the rest of the time). We are hoping that you fine folk can help point us in the right direction. As this is on a student budget, you can probably imagine that we are trying to be frugal where possible. We are hoping to keep the whole project under $3k + the cost of the plasma cutter.


  1. Active Torch Height Control: Is this necessary? We will only ever be cutting 1.00" OD and 1.25" OD tubing. If we can design it so the cutter sit's at one of these two preset heights, is the height control strictly necessary? To my understanding it is mostly needed on thin flat sheet because the heat distortion can warp the workpiece towards/away from the cutter. Because we will be cutting tubes, I think that the circular structure will prevent the cut edge from deflecting too much. Is it required for other reasons?
  2. Manually moving the tube between feature locations to reduce machine size: Most tube lengths we are cutting are about 2-6 feet long. This means a "traditional" cnc tube cutter would cut one end of the tube, travel 6 feet, and cut the other end of the tube. The features cut and engraved on the tubing really only require 2-3" of axial tube movement. Is there a sensible way we could design the machine to only need 2-3" of travel? I don't know what this would look like in the g-code/programming side, but we are envisioning the following for our machine:
    - Machine cuts first tube end
    - Tube is manually repositioned to next feature location
    - Machine cuts/engraves next feature
    - Reposition tube to next feature etc.
    I'm sure this can be done, but I'm not knowledgeable enough about g-code programming at the moment to know if this will be hard to implement or not. We want to make the machine user-friendly, so ultimately I'd like to have one g-code program to cut all the features for each tube, but for it to pause/resume for each tube repositioning at the click of the button or something.
  3. Recommendations for a budget friendly computer controllable plasma torch? The hypertherm powermax 45 is on our wish list, but it is quite costly. We will only ever be cutting 0.035"-0.065" thick chromoly and mild steel, so it really does not need to be a high-power machine.


Thanks so much for your help in advance! I have really enjoyed perusing some of the active DIY projects on this site, and I hope to post my project as we get into it!