I have concluded most of my tests on using the MASSO with the KRMx02 CNC Router.

Just a few things first.



Yes or No to the MASSO?

Update 11/16/2017

Originally I had answered yes to this question, but after further testing of the MASSO I can no longer recommend the MASSO for use with the KRMx02.


!!! NO !!!!


The MASSO has some underlying resolution issues when dealing with machines that have a lower step to distance ratio.  This means that systems with a R&P drives or 5 or 8 start screws are going to have problems.

Originally the problems manifested its self by the Gcode going south while running a job. The folks at HTG, fixed this for the most part, but it is manifesting its self in other ways.

After connecting my MASSO to my krmc01 milling machine, I connected my MPG to the MASSSO and while the masso did add extra steps they were only on the X1 and X10 resolutions, and then not as frequent.  On the KRMx02, much more extra steps on the X10 and X100 resolution. On the X1 resolution the MASSO misses about 90% of the steps.  This only leads me to believe there is still a fundamental issue with the step to distance ratio. Also note that this happens if the machine is setup in inches or mm.


Bottom Line, the MASSO is not a good fit for the KRMx02 CNC or any CNC that is using a R&B drive, or 5 or 8 start screws.  Note that I am using a Gecko G540 and this has a fixed micro-stepping of 10-1.  If you are running a 16-1 motor driver, you may be able to get away with a 5 start screw.



Other MASSO Issues

The following are a list of points that I made note of as I was getting to know the MASSO.


MASSO Config Startup Issue

While working with the MASSO controlling the SuperPID 2, I needed the spindle CW signal inverted. The MASSO provides the ability to make this change, but he change to this new state requires a little time when the MASSO boots. I would get a brief power up of my router each time the MASSO is booted. The fix for this was to add a small relay board and let that do the spindle CW inversion.

See my writeup here:

MASSO and the SuperPID


No Way to Stop a Job

While you can pause and start a job, there does not seem to be a way of canceling a job. The work around that I used was to hit ESC to pause the job, then toggle the Estop. The down side to this is that hitting the Estop can mess with your origins a little.


Feed Speed Override Issues

The MASSO allows you to decrease the feed speed manually while running a job, but it will not allow you to increase it above 100%.  When milling a new part for the first time, I find it extremely helpful to increase or decrease the feed speed while the job is running to help dial-in the final settings.

The spindle speed override allows this, and so should the feed speed.


Speed and Feed Override Reset

There is no way to reset the feed/speed/rapid settings back to there default. You have to use the arrow keys and this can get tedious, especially when jogging.


Position Save on Shutdown

It would be nice to have a shutdown command so that the machine cords and current offset could be saved for the next boot.  Currently you have to re-home the machine when you restart.  Sometimes due to fixture this may not be possible. 


Homing Issue

If one of you homing switches is making contact before you start the homing sequence, the MASSO gets confused.  One or more of the axis may move in a direction its not supposed to. This could cause it to crash.

Eventually the MASSO will give an alarm and stop.


Pendant Step Issues

When moving a pendant in single steps, sometimes the MASSO will move more than one step.  This is not a pendant issue as I see it on multiple pendants.


More Pendant Issues

When using the X1 resolution on the pendant, I have to make several revolutions to get the MASSO to responds.  Overall I found the use of the pendant to be kind of clunky and the operation of the MASSO to be kind sticky.


No Job Time Indicator

I find it extremely helpful to have an actual Job Time indicator as the job progresses.  This helps me later when I run subsequent jobs. Currently I have to use a stop watch and keep an eye on the part.


PlayStation Controller Deficiancies

While the MASSO supports PlayStation 2 controller for jogging, it pretty much emulates the keyboard.  They analog controls should be allowed to vary the speed while jogging.  In addition the ability to toggle the step and continuous modes without having to hold two buttons should be added.


No Wifi

The MASSO does not currently support Wifi, so files must be moved from your PC to the MASSO via a thumb drive.  Very inconvenient if you are doing testing on a new part design.



The MASSO has a few issues when it comes to jogging. First you can only jog when on the jog screen.  Then when jogging its done in step mode.  To jog in continuous mode you must hold down a shift key.  This means two hands must be on the keyboard to move the machine from point A to point B.

HTG needs to add a toggle key that allows you to jog using the arrow keys in step or continuous mode.

To change the jog speed when in continuous mode, you need to use the + and - keys to change the actual speed.  This can take a while going back and forth between full rapid jogging speed and safe positional speed.


Custom Macros

The MASSO does not support custom macros or plugins. This means you have to take things as they are and live with them. With Mach3, it has a couple built-in ways of adding custom commands/macros.



In order to probe on the MASSO, you must unload any job you have loaded and load a Gcode program to probe.  While this does work I found that I tended to omit the gcode and just position the tool manually.  This is partially due to the fact that it take the MASSO a long time to load gcode.

Here is my Z probe Gcode:

Probe Z Down


Other Observations

These are some observations that I noted while doing my research.  They arent really problems, just things you should be aware of.


MASSO Connectors

Don't try and remove the small terminal block connectors.  They look like they are removable terminal blocks much like thos I have seen on other boards.  But they break if you try and remove them.  


Estop and the G540

The MASSO fires an external relay in order to enable/disable your motor drivers. While this works fine with the G540, it does not allow the G540 to pass on any of its faults to MASSO.

To solve this porblem, I used my G540 to handle the Estops and in turn pass them on to the MASSO.  This allows the G540 to trigger the MASSO if it encounters any of its own faults.

You can see my writeup here:



Initial MASSO Firmware

The MASSO ships with an early version of its 3 axis firmware. Once purchased you must contact HTG, in order to get the latest firmware and activation of any additional Axis.

That said, the actual use of the MASSO to control the KRMx02 only requires the 3 axis firmware. You can easily purchase the upgrades for up to 5 axis later.


Modbus Interface

The MASSO seems to  have a Modbus interface but it is not documented or used.


Job Loading Time

It can take a very long time for the MASSO to load complex files.

This particular file (Small Gear) has just over 9000 lines of Gcode and took just about 44 seconds to load.

Just be aware that some files can take a very long time.  What if I wanted to mill 10 of these in a single job.



Don't use the MASSO on the KRMx02. If you do, I wont be able to help you as I no longer own the MASSO.