CNC Conversion

Last Updated: 12th January 2011

Shortly after acquiring my laser cutter I also bought a Sieg X1 Micro Mill with the thought that I might convert it to use CNC. While researching the options I found something on the RoutOutCNC forum about how they'd also converted a laser cutter, similar to mine, over to CNC using Mach 3 to control it.

I wasn't familiar with Mach 3 at the time but it seemed to be regarded, amongst home/hobby machinists at least, as the software to use with regards to CNC. Going off the instructional videos on their website it seemed very capable and, having almost decided that's what I wanted for the micro mill, the discovery that I could use the same controller boards and software for the laser made it too tempting to resist.

Mach 3, breakout boards, controller boards, and stepper motors were purchased from RoutOutCNC, while hardware for mounting the motors to the mill came from CNC Fusion.

The Plan

My initial plan was to convert the mill and have a good play with Mach 3 before making a final decision about how to convert the laser cutter. This was because I was thinking I might do it such that I could throw a few switches to choose between the original set up with NewlyDRAW and the new one with Mach 3. However this changed after I killed the original controller board.

I'm not 100% sure what happened to it but the fact is that I took the machine apart a couple of times to assess the possibility of increasing the bed size. I'm pretty careful with this stuff, anti-static precautions and all that. But the fact is that it worked before, but not after, one of my exploratory dismantle/reassemble operations does kinda suggest that I killed it.

It didn't make any sense for me to spend the 91 UKP it would cost for a new one so converting the laser was brought forward with with the new stuff simply replacing the old.

Software Installation

Installation of Mach 3 onto the same PC laptop I used for NewlyDRAW was straightforward; as per the videos on the Mach 3 website. However, when I did the test (see the video) my waveform was horrible and nothing like their nice clean one. I found the solution in a post on the Mach 3 forum where DaveC says:

The secret is .... disable the ACPI driver!
Open the device manager and find the 'Computer' icon.
Click on the plus next to that and you will see something like Advanced Configuration and Power Interface (ACPI) computer. Chose the 'update driver' option and select 'Standard PC' as a replacement.
Windows demands a reboot after this, and a lot of the hardware had to be 'rediscovered' and reinstalled (all used drivers it knew about already, so was painless), another reboot for good measure and now it works flawlessly.

Thanks Dave.

Motors & Switches

PSU Connections24v for the motors is easily obtained from the 5v/24v PSU board. On mine the connections we want are the middle two marked marked GND and 24V.

While we're here:

L and 5V are for the optocoupler that we can also see in the image. We won't be using this for reasons I'll explain later.

VGND and 5V provided a 5v supply to the old controller board. Again, we won't be using this for anything.

The original motors and home switches have 4 wires coming off one motor, and a flexible flat cable (FFC) coming off the other. FFC connectors are a bit tricky to track down so I decided it make more sense to replace most of this.

In fact the 4 wires coming off the Y-axis motor are plenty long enough to reach the terminals on the new controller. The wires coming of the X-axis motor need extending. Using a continuity tester it's easy to identify the two pairs in each group of 4. Apparently it doesn't make any different which are designated pair 1 or pair 2, or which is designated A and B within the pair.

As per the information at RoutOutCNC I set the controllers to 1 amp and 8th step. However I found that the motors tended to be noisy when stationary and the X-axis motor ran hot. I reduced the current to 0.5 amp, which seems plenty and resulted in cooler, quieter, motors.

I have purchased some micro switches to be installed as home switches but have not done this at the time of writing this. Watch this space.

Controlling the Laser Beam

I had a little more fun when it came to being able to switch the beam on and off via software. So much so in fact that I've written up a whole page about controlling the beam which describes the wiring, the problems I had using the wiring, and why I control the beam using M11P1 for on and M10P1 for off rather than M3 and M5 that you probably anticipated (assuming you already know something about NC programing).

In Use

My first test of the new system.The image to the right shows my first test with the new system and Mach 3 users will recognise it as being from the roadrunner G-code included with Mach 3. Things to note are:

  1. I have pin 6 on the breakout board set to behave as if it were controlling a spindle relay. As the roadrunner G-code is written for a mill, the spindle is switched on at the start and left running until the end. Consequently we have lines cut where the head is moving from the end of one chain to another. We also have holes being cut whenever the mill's cutter would be being moved in the Z-axis.

  2. While cutting I was twiddling the power knob on the control panel of the laser cutter (which is why we have lines of different 'thickness'.

Clearly I now need to invest some time in learning the ins and outs of LazyCAM (supplied with Mach 3) and G-code as it relates to my laser cutter.

Once again: watch this space.