G code sender for grbl

[John HaineParticipant @johnhaine32865]

I'm just finishing the mechanics for the x axis power feed on my VMB which uses a stepper motor. I'm also going to add power downfeed as winding the head up and down at 0.5 mm per turn on the handle is tedious to say the least. I have a spare arduino uno and I'm thinking that using grbl to run the steppers would be neat, but need to generate g code strings to send it on the serial interface to make it move. They will need to come from some sort of processor with a user interface, I don't fancy another PC, but have at least 2 old Android phones that might be used.

So, has anyone seen an app that might do this please?

[John HaineParticipant @johnhaine32865]

[IanTParticipant @iant]

John,

I don't have the Android app that you'd like and I almost hesitate to suggest my solution. However, here goes!

I would use a 28pin 'Micromite' for this. I have several just built on (what I still call) Veroboard and they essentially just need a PIC32 MCU chip and two external components (a resistor and capacitor) to form a working system. They are very simple to hook up to just about any device and for instance I use £1.50 TV remotes to control mine using an IR connection. Very simple or (if you want) very complex LCD screen support is provided. I programme my own PICs but you can get them pre-programmed. They boot standalone once programmed via a serial lnk to a laptop.

Or you could of course use an Arduino or more traditional PIC controller.

So why a Micromite? Well because Micromite Basic (MMB) is just so nice to work with interactively. Just one line to use the IR control, just one line to 'PWM'control a servo or motor, simple serial comms (and many other comm. protocols) all embedded in the language.

Forget any prejudices about using "Basic" (I had them) this is a modern language (no line numbers) and is more than fast enough even on the 28pin MM. However, if you ever need speed, there is now a large range of devices that MMB runs on – faster PIC32s, ARM Cortex devices, R.Pi and PCs

But the best reason to use MMB is for ease. You can programme a Micromite interactively from your PC screen and debug it the same way. No compile, load, test, recompile etc cycle that is required of most micro programming systems – including Arduino. If someone has a quick solution, then of course use it. But if you find you need to cook your own, then the MM will get you there faster than any other solution for this kind of programme control. I know many here will disagree – and to them I'll just say, I've tried other solutions and MM is the one I much prefer.

It is also very well documented and has an active (and friendly user forum). Start here…

Micromite – Geoffs Projects

Pre-programmed Micromites, PCBs from a UK source here

Micromite in UK

That's it. If you try this I think you will be pleasantly surprised with what an elegant solution MMB is – even on a simple Veroboard with just a few components.

Regards,

IanT

[Ronald MorrisonParticipant @ronaldmorrison29248]

I can't help you with any app for an Android but I use a Raspberry Pi 3B as the computer to drive my Arduino and have the choice of Universal Gcode Sender or bCNC. They both work for sending the code but I can't get the toolpath to show on UGS while bCNC does. The setup feature in UGS makes adjusting the steps for accurate movement a lot easier than doing it by hand.

[John HaineParticipant @johnhaine32865]

Thanks for the suggestions. Ian, I've got nothing against Basic but given some familiarity with programming Arduino's and Pi's, and a spare Pi, I don't really want to start using another processor!

Ronald, a Pi is another alternative actually except that I'd also need a screen/keyboard – or maybe an Android running VNC? Hmmm…

Food for thought!

[IanTParticipant @iant]

No problem John.

I was envisaging a simple system using a stepper motor, driver board and simple (stand-alone) embedded controller to simply drive the head up and down in a controlled manner. I don't really think of it as being a "processor" choice but more one of choosing a nice development environment – as I use/run MMB on PIC32s, RPi3 and my laptop. Haven't got any ARM Cortex devices yet but they are available.

Btw – I have an E64 MM+ board that has SD storage onboard that I use as a kind of Swiss Army knife – for testing servo motors, signal generator etc – I just load the programme I need. It plugs into a breadboard for testing peripheral devices before they disappear onto dedicated boards based around the 28 DIP device thus far.

I like the simplicity – I turn it on and it works. My RPi is very fast but far less friendly (or forgiving)…

Regards,

IanT

[Andrew EntwistleParticipant @andrewentwistle]

Hi John,

I use an Android App called Grbl Controller to send Gcode to a 3-axis Eleksmaker Grbl controller over Bluetooth serial (based on an Arduino nano with added HC-05 or similar Bluetooth module). The motherboard and nano cost little more than £20. It works very well and the App is free. you can send Gcode files, or just use up/down left/right etc buttons on three axes. I think it came pre-flashed with Grbl, but anyway no editing required, except for maybe baud rate in the config.h file.

Andrew.

 

Edited By Andrew Entwistle on 12/05/2020 13:51:14

Edited By Andrew Entwistle on 12/05/2020 13:53:05

[BazyleParticipant @bazyle]

Since you haven't mentioned the y axis I take it CNC is not intended so using GBRL is backward step. As you are a bit into software why not knock up a few switches and potentiometers to give various speeds, movements like home, move away and back for measurement, cycles for facing off like traverse – lift cutter – return to start – reset cutter – repeat with you manually incrementing the y axis.

[Ex contributorParticipant @mgnbuk]

Grblgru

I have installed this & had it communicating with the latest Grbl version (v1.1) on an Arduino, though have not yet tried driving a machine with it (machine still not ready).

Also had Universal G Code Sender doing the same UGS website

Nigel B.

[John HaineParticipant @johnhaine32865]

Andrew, that looks like it might be just the thing, I'll give it a go.

Bazyle, though I don't want another CNC mill, GRBL handles all the hard stuff like acceleration profiles etc, it's free, and it will run on a UNO, so why not use it? Only problem is it wants to be sent g code to tell it what to do so need a UI to do that, which means a processor of some sort. I don't know yet what functions I want, but I can see that the ability to make canned functions will be useful so g-code is the way to go I think.

[Michael GilliganParticipant @michaelgilligan61133]

Have you seen these, John ? **LINK**

https://www.ebay.co.uk/itm/Offline-Hand-Controller-Manual-Control-for-GRBL-Control-Laser-Engraving-Machine/113002082998

… I keep wondering whether that might be a good option

MichaelG.

[Ronald MorrisonParticipant @ronaldmorrison29248]

Take a look at this mill controller. Since all you want to do is move the table of the mill this might work for you. It does need an Arduino Mega 2560 as an Arduino Uno does not have sufficient memory space.

[John HaineParticipant @johnhaine32865]

Hmm..but as far as I can see grbl will run on a standard Uno…

Thanks for all the inputs – it looks like Grbl Controller may well be just what I need, I'll look into that and report back.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Haine on 12/05/2020 21:37:30:

Hmm..but as far as I can see grbl will run on a standard Uno…

.

grbl 1.1f will just fit, and happily run, on a nano

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

< deleted double post >

Edited By Michael Gilligan on 12/05/2020 21:48:27

[Enough!Participant @enough]

Bit of a slefgehammer-nut approach but wouldn't a RAMPS kit do this?

(Or Banggood etc)

[Andy CarlsonParticipant @andycarlson18141]

Not quite answering your question but I started with GRBL on an Uno and ended up running Marlin firmware on a Mega 2560. If you run Marlin then you have the option of an LCD screen and a memory card on the controller itself as well as running off G code from an external 'sender'.

My own reason for running Marlin was software backlash compensation. GRBL also has a version that can do this but it won't fit on an Uno – you need a Mega 2560… the killer for me though was that moving to GRBL on a Mega means moving to completely different I/O pins and therefore not being able to use the CNC shield. I was able to set up Marlin to work with the CNC shield.

On the downside, Marlin's 'sweet spot' is 3d printing so it is a bit odd for CNC.

Regards, Andy

[John HaineParticipant @johnhaine32865]

OK, well I have now completed the hardware and software build for my power feed controller, based on…

• Arduino Uno that I had lying around
• CNC Shield from Protoneer
• A DRV8825 stepper driver on header PCB from Polulu
• GRBL v1.1f
• HC-06 Bluetooth adapter
• 24 + 5V SMPS from RS
• GRBLController running under Android on my smartphone.

Very few problems along the way, mainly caused by the poor documentation of the Bluetooth module and non-functional "easy configuration" software. The hardware is built into a home-made box that will be tucked away on the shelf underneath the mill.

I can now drive the mill table using the GRBL Controller jog screen and programmable speeds. Now I need to work out some simple routines to add to the quick buttons on the screen for doing common jobs.

I'll take and post some photos tomorrow.

Next job: add a Z axis feed to deal with the tedium of winding the VMB head up and down!

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