X/Y label plotter to vinyl cutter and pen plotter conversion using grbl

I've a found a plotter. The VP600 Basic by Brady is a X-Y pen plotter for tag.

Of course there's some part broken and missing.

The pen holder and the power supply are missing, the plotter has a dent on one side, software is missing and also I'm not sure electronic is working.

I disassembly it, repair the dent and check that the X-Y mechanism is working.

It has a small piece of plastic of the X axis broken, so I've to glue it. Apart from this, the hardware is working, at least what I can check without connecting it.

Because the missing parts I've decided to convert it to something else, something I don't still have. So a vinyl cutter.

First step is to build the electronic board. An Arduino Pro Mini with a ATmega328 can work for me.

The firmware I've selected it's grbl (https://github.com/grbl/grbl), but I've to compile a version that works with a servo as Z-axis, cause my holder will be based on a servo.

The pcb is simple, the grbl docs page contains all the information about wiring. I've to wire two stepper motor driver board, A4988 based, and just a straight wire for the servo conroller, which will be a mini RC servo.

I've assemble the PCB under the original PCB, reusing the USB and power plugs. That way I can use the original case holes for connections.

The motor of the plotter are 4 wires, just follow the grbl guidelines to wire it. Find the correct wiring diagram is just a matter of finding the stepper motor coild using a multimeter reading resistance between wires.

Now the holder mechanism. I've take the design from the following project https://www.instructables.com/CNC-Pen-Lift-1/. I've copied it and adapted to my needs.

I've buy a Roland plotter compatible cutter and adapt the holder for my cutter.

I'll use GRBL plotter (https://github.com/svenhb/GRBL-Plotter) as software.

I've covered the plate of the plotter with a plastic 4mm sheet, this will prevent the cutter blade to break on the original alluminum base.

Then I've to set the step steps/mm for each motor. There are plenity of pages teaching how to do this, so it's just a matter of reading and applying the procedure.

In my specific case I've set

$100 80.240

$101 80.240

Also I've to set in G-Code Generation tab of the GRBL plotter the Pen up / down translation to PWM, then set the PWM op Pen Up function to 1000 and Pen Down to 0.

One the plotter is set I've to select the proper spring for the holder. The holder spring defines the cut strength.

I've made some test. What I've found is that cutting vinyl is not so simple, the most difficult thing is to find the right cut spring. At the end of the day the cutting quality is acceptable to me. Not as accurate as a pro machine, but as much as I need, and also I've saved a plotter from the junk.

Notes

• read risk disclaimer
• excuse my bad english