Controller ideas for split Y axis for rotary engraving

Random or Off Topic
1

I built a laser engraving MPCNC and would like it to support a rotary axis. I have found many topics within the forum on how this can be done.

Based on my findings, the best route is to leverage the Y-axis to run the rotary.

Goal:

  • Make it easy to switch between the traditional XYZ function to Rotary Y and X functionality
  • Leverage the traditional Y steppers and end stops to put the Y in the proper position and have the steppers hold positions.

Ideas:

  • Leverage relay modules to switch from traditional XYZ and Rotary and X function
  • Don’t lose the functionality of traditional Y
    • I would like to say G01 Y150 and have it hold that position while engraving
      • thought was to use a cheaper controller that I can use both traditional Y and dual-end stops
        • Don’t want to use a Rambo 1.4 as it pretty expensive to handle a single axis.

If this all seems like a possibility.

Can anyone recommend decent board that can run marlin that is fairly cheap?

2

On my K40 (on which I run a CNC Shield/Arduino controller and grbl firmware), my approach is to power down the laser cutter and simply swap the Y axis stepper plug with the plug on a stepper on the rotary attachment. I’ve got a simple “script” of grbl commands to adjust settings like axis limits and steps per mm for Y versus rotary. For homing on the rotary, I either just click the Y limit switch by hand or modify the homing command to skip the Y axis from the gcode file before starting the job.

I don’t need to worry about squaring things up as I’ve got pins that align the rotary when I put it in place.

3

My concerns is that the traditional Y gets bumped during engraving since the motors are off.

4

I haven’t had that be a problem, but it may be due to the fully enclosed nature of the K40 mechanicals.

5

I know my idea may be way out there.

I am surprised there haven’t been any other recommendations for cheap controllers.

Requirements:

  • Dual motors for Y
  • Dual Endstops
  • Low priced
6

Can anyone recommend decent board that can run marlin that is fairly cheap?

The word “decent” can mean many things. The common answer to this question would be a Ramps 1.4 board. It is a combination of an Arduino Mega and a companion board, and this configuration has the same microprocessor as the Rambo. A setup with drivers (no screen) will run you about $30. V1 maintains MPCNC and Lowrider firmware for this board running DRV8825 drivers. The downside to this setup is that it has less electrical protection then the Rambo, so it is much easier to damage or kill the board (usually by user mistakes).

The MKS GEN L boards are pin compatible to Ramps boards and therefore can run the V1 maintained firmware for the Ramps boards. They also run around $30.

If you want a bit of adventure, you might look at the MKS Tinybee. I don’t see it available on Amazon, but the board and drivers run $30 off Aliexpress. It runs Marlin, but I don’t know of any MPCNC that is currently using this board. I know one person was working on a build using this board and FluidNC as the firmware. The one downside for this board (beyond not having V1 maintained firmware as a starting point), is that it only has 3 dedicated endstop plugs. You would have to repurpose two other plugs to get the five plugs. The upside (beyond cost) is that it is a 32-bit board with built-in wifi.

Two other boards that are often cheaper in certain areas are the SKR Turbo boards and the SKR 1.3 boards (not to be confused with the SKR Pro 1.2). V1 maintains untested firmware for both.