CNC Plasma Cutter Iteration 1: Z and X Axis Redo

by Joey Sacco on May 05, 2014

Iteration 1 was a magical creation. A pile of steel and parts were assembled and molded into a working CNC machine. Who would've thought? Well, as with any project, there are always improvements to be made. Several iterations must be performed in order to perfect a design. What was wrong with iteration 1?

- The X axis had too much flex. It was only tack welded in the beginning, and we ran this way for some time because it worked...kinda.
- The Z axis was extremely slow. Touch and go took so long that I would almost nod off in between cuts.
- The floating head linear slide that was purchased had so loose a tolerance that it made the torch jiggle during motion.
- The converted hand torch to machine torch - it still performed as it did as a hand torch. It was just easier to mount.

The goals of iteration 2 were to stiffen up the X and Z axes, and speed up the Z movement. Well, iteration 2 was a success, for the most part. As before, the design was drawn up in CAD, though things are always a little different when the parts are cut out and in your hands. It's pretty cool that this machine can make itself... better. With our helping hand, of course. We haven't created a Johnny 5 here.


Here are the plates being cut out.

The plates and gussets tacked up for testing. They are already looking much better than the old ones. With the help of iteration 1, and a little CAD manipulation, these parts are able to made lighter and stronger.

Here is Iteration 2, mounted on a mock up 2"x2" tube for testing the bearing fit. It was perfect.

Here, we can see Iteration 1, next to Iteration 2, Iteration 1 being on the left. The new design is much smaller, lighter, and better looking. The Z axis motor is no longer a counterweight to add to flex during movement, but acts more like a counterweight to prevent any stray movement, since it is closer to the pivot point of motion. We decided to purchase a genuine Trafimet S45 machine torch from Everlast to try and resolve the arc dropping issues. We still had the same problem. In their defense, we did not activate the low cost torch height control (LCTHC) until after our Hypertherm purchase. We ran a few trial runs with the LCTHC on the Trafimet machine torch, and we were still having some arc dropping issues. Though, we did not use it enough to let the Everlast prove itself.  Honestly, our converted hand-to-machine torch performed better, LCTHC or not.

With the new Iteration 2, we figured we would update the floppy floating head at the same time. If you recall, the Iteration 1 floating head was purchased on eBay. It was very loose in tolerance, but did the job for a while. With Iteration 2, we decided to use the V-rail for both the Z axis and floating head. They both share the same rail. It turned out pretty well. Though, there are always improvements to be made. So, stay posted!




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