You Know You Want a Revolution

[Mooselake]

After almost a year I've replaced the Revo's controller (a CNC Shield V3 on an Uno clone with a slightly modified grbl to change Y to A) with one based on FluidNC. FluidNC is the new name of grbl_esp32, which runs on a 32b ESP32, they changed the name after seriously modifying the configuration system to use a text file instead of recompiling. I'm using a Wemos D1 R32 board, an ESP32 in an Uno form factor, with the same kind of CNC shield (wanted to keep the original controller intact), and it's configured for 4 axes, X, Y, Z, and A. About $20 for the board, shield, and DRV8825s, can't beat that. Can't test Y, but the rest work fine. I had X homing issues that turned out to be a combination of a bad switch and it's being located so it was just barely compressed. A change of switch and a screw to adjust the trip location has that fixed.

FluidNC has a built-in web server with a pronterface style jog interface, a grbl command line, streaming log (I keep position status messages turned on for now, they also include home switch status), and access to almost all configuration variables, and you can upload/download to/from the ESP32's onboard file system. It can communicate via USB, bluetooth, and wifi via telnet. SD card support, but my board doesn't have one (couple bucks and some soldering to add, but haven't bothered). It's just enough different that most gcode senders have minor (to major) issues talking to it, mostly because they try to read the firmware variables that are pretty much gone. The latest UGS nightly works, while it's at the bleeding edge I haven't had any problems.

Besides going round and round the A axis is pretty interesting. First infinite axis machine I've ever had, I do blank rounding with commands like G1 X200 A12000 Z35 F5000, the A value calculated to give the right stepover. One command to shave off the entire length of an up to 24" blank, although you really don't want to do a G0 X0 A0 unless you want to see it spin for a while, best to rezero A... VCarve Desktop will do decent 3D carving, but you have to keep in mind that it's mostly 2D wrapped around a round object, and it's not aware that A goes past 360 so it does unnecessary direction changes. The only exception seems to be when doing designs that exceed it's workspace boundaries, for example I've been doing straight diagonal lines that can wrap flutes around the cylinder. Rather than faking it and manually figuring out where it goes off one edge onto the other it'll keep going for you. I was hoping it would raster 3D round and round, but it stops at 360 and changes direction. Oh, well.

FluidNC, other than the homing problem (it does a hard stop requiring a reset and losing workspace offsets if the switch doesn't release when backing off, a fix is in the works) has been solid, and I'll be changing out the controller on my 3018 and converting the ZB Mini from grbl_ESP32 when I get around to it. That machine uses a plug-in DevKitC module so I can pull the existing module and replace it, and still have a viable backup. They're about 10 bucks on Mouser and I have a few on hand. The CNC shield requires cutting and removing it's only through-hole resistor. That pulls the stepper enable lines to +5, and the ESP32 lets the smoke out when that happens, and trashed my first board (it lost wifi but still talks across the USB, might try throwing micro python it). Pretty amazing what you can get for 10 bucks these days... I haven't really pushed FluidNC very hard so I'm not taking advantage of it's much higher step rate and command processing ability. It has a much deeper command look-ahead than 8b grbl, it might be running smoother but that's subjective. It should make a big difference on jobs that use teeny tiny lines for arcs, that's on my list to try when I'm done having fun with the machine and playing with VCarve.

Kirk