I bought my first plasma cutter 2 years ago. Once I got it out of the box I knew I was going to have a lot of fun learning and creating metal transformation techniques. I also learned I needed some motion control over the machine to create predictable and consistent results. This was the beginning of a journey.

The Lotos LPT5000D. I chose this machine because it has the pilot arc feature, had fair reviews, and was in my price range.

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It took a few days to get the wiring installed for the 240V service. Once I got it running I made a few passes on some scrap metal. It is like a knife through warm butter. I immediately knew I needed some help controlling the cutter.

 I did some research online and found some plans for a pantograph. So I built one.

The pantograph was simple to make. The only welded components are the main pivot and the torch holder. I added a supported tub to the side of my work table and built a grate from an old bed frame to hold the work.

Changing the location of the pivots made the pantograph adjust the size. I could trace the actual size, or make it bigger or smaller by moving the bolts. In the image you can see a modified TIG switch. I bought it online and wired it to the plasma cutter so I could turn on the plasma without touching the torch. It took 2 hands to use- one for tracing and the other for the torch.

I cut a few pieces, with mixed results. It did not take long for me to decide I needed more machine control and my journey changed focus on CNC. Within a few days I committed to using a design Absorber of Light documented in a very well done YouTube series. I varied my design as I went along.

I used 3 wheels for each side of the axis. I used roller blade wheels to provide pressure to the lower rail.

I used some 1×1 tube steel to align the axis. It moves freely back and forth.

Roughing up the Z axis and getting it aligned. In my first version I used 1×1 welded together for the top rail of the gantry because I had a ton of it left from another project. In the end, the gantry is all 2×2.

The gantry, roughed in. I changed my mind a few times as things were coming together and ended up with a thicker piece of angle iron as the riser for the gantry because it allowed me access to the bolts holding the roller blade wheels if I need it in the future.

The Z axis is made from drawer slides welded to 1×1. I used some 1″ strap to hold the top and bottom slides to the gantry. The clamps in the photo held the Z axis from falling while I welded it all together.

X, Y, and Z access of my home made CNC are tacked together. Things run very smooth with the variety of wheels and bearings I used.

I started adding the components for motion control. The lower assembly is shown in the photo. I added skateboard bearings to each side of the axis on the inside to control any wobble, it really stiffened up the axis. I welded the plate and riser to the cross member in the center. This will fix to the ACME thread and drive the axis back and forth.

Motion control for the CNC is installed and I started wiring the electronics. Each end of the ACME rod is in a swivel to stabilize it, and each rod has a mounted nut in the middle to drive the axis.

I added some wire management to the top of the gantry and modified my tool holder to take a pen. I mocked up a plasma torch holder and waste table because I was very eager to get things running. However, I was experiencing a lot of problems with electromagnetic interference. I continued setting up the machine to draw with the pen holder while I was working through many attempts to resolve the electromatic interference problem On the right you can see the laptop station. My first configuration was Linux Mint and I used Universal GCode Sender.

My frustration, and hours of wiring changes, grounding changes, configuration changes, computer and electronics changes continued for many months. 

bCNC was one attempt I made on software for my CNC. It was very tricky to set up and hard to configure.

Drawing tests with each configuration change made me confident I was on the right track. However, I would never get past the first step with plasma. I continued making wiring changes which were time consuming because I had to translate wire color changes from the motor to the driver each time and had to make several checks to make sure there were no accidental grounds (it burns up things sometimes).

As I continued to test new methods I hoped would resolve the electromagnetic interference problems I made a complete change to all of the electronic controls. My first implementation included an Arduino with a CNC shield. It worked for machine control but I burned up the shield. I decided to use individual drivers and harvested an old PC chassis to hold my controls.

The power supply is adjustable and I have it set to 24V. I take the leads from the power supply to a breadboard for the electronics. I ran separate power to a toggle switch to the fan that was in the PC chassis and another fan I had from my earlier electronics box.

I cut a scrap piece of sheet metal and mounted TB6560 drivers with plastic standoffs and attached it to the PC chassis. I wired things up using breadboards for the common connections and set the DIP switches on the drivers. The cutoff switch only kills power to the drivers. The power for the Arduino is a combination of the onboard USB and a power supply.

Every time I had a chance I was reading articles and consulting with friends and internet resources about the plasma problems. In the meantime I modified my tool holder to support a trim router and cut several patterns. The black material is chalk board stock I found in the cull pile at Home Depot. The machine is very accurate and very fast. I purchased Estlcam software for machine control and am very pleased with it. The configuration for the wood cutting was very simple using Inkscape and Estlcam.

Still, the plasma did not work. From the first steps in my plasma adventure I learned a lot. From no knowledge on how to build and configure a CNC I made a machine from scratch. I started in December 2016 with a simple objective to buy and use a plasma cutter. Today, 2 years later I am in the final stages of my journey and very close to achieving my goal. For months and months I was focusing on resolving the electromagnetic interference problem with my CNC. On a whim I started looking at how to configure the plasma cutter itself. While I was on the manufacturers site I saw a new model- the CUT60D and in the description I read something I had missed in all my research on the EMI problem. The CUT60D features include a ‘blowback’ start that prevents known issues with the pilot arc interference. After some additional research, I decided the new plasma cutter would likely solve my electromagnetic problem. I bought it.

Now, 2 years later, my goals are in sight. I used my DIY CNC to cut steel with my plasma cutter. I still have some things to complete before I claim victory. I need to automatically turn on and off the plasma- possibly using torch height control and the built in CNC controls on the plasma cutter. More to come…