Patterson Paxton (MicroKinetics) Lathe Upgrade to ESP32 GrblHAL

This guide explains how to convert a Paxton / Patterson Lathe from the 2000s into one that has support for GRBL GCode commands, and other features of the ESP32 microcontroller. MicroKinetics sells/supports their own software and hardware which designed to be compatible with existing hardware but it is relatively expensive. The standard 8-bit Arduino with the grbl shield and grbl firmware is too slow.

1. 2x Model 6600 stepper motor drivers
2. grblHAL supported Microcontroller (such as Makerbase DLC 32-Bit)
3. Laptop or computer
4. USB cable
5. Power supply
6. Wires and wire splice connectors

Move the CNC onto a stand. It's heavy so lift with two people. Open the screws for the bottom hatch. If the screw heads are rusty and break off, you can cut them using a Dremel rotary tool with iron-oxide grinder blade. The panel will swing down from the hinge. The wires are all neatly labeled. The two stepper motors are for Z and X axis. You will find the end stops but they are not needed like a 3d printer.

Each stepper motor has two pairs of wires. You can detect which pairs are connected using a continuity tester on a multimeter. The wires are called pairs A and B. The stepper drivers can use up to 24v. I used a bench power supply set at 23v and 5a maximum. The speed controller is a AC power PWM driver from Harbor Freight Tools. The built-in speed controller stopped working. The back of the wood stand has a power strip attached.

The firmware is grblHAL for 32-bit controller.

A flaw in the firmware is that the minimum feed rate is 1mm/s. You can get around this minimum speed limit by interspersing dwell G4 P0.5 commands between the movement commands to slow down the tool.

More commands can be found here: http://wiki.fluidnc.com/en/home

For example,

The software used to run Gcode is Universal Gcode Sender.

Here is a test program that moves the cutter against the work piece.

It removes about 0.5mm from a 5mm length x 5mm diameter stainless steel standoff.

The run time is about 1.5 minutes. The first step is move the cutter to just barely touch the part. Then set the Z position to 0.0mm. Moving towards the part in the chuck is negative on the Z-axis.