Help with CNC 3018 from Banggood

[Doddy]

Complete guesswork here (without seeing your controller board - but you're suggesting some local controller, likely a microcontroller GRBL - complete guess, like I say), IF (guesswork again) the limit switches are couple to the ucontroller discrete inputs then you might be suffering with the intrinsic high-z inputs from the uC device with internal pull-up or pull-downs.

Are the microswitches wired to 0V/Ground? If so, is the switched input (the non-ground wire) floating at around 5V?, if so then you could try reducing the internal pull-up resistance by wiring a 1k resistor from the microswitch input to a local 5V pin. The point here to provide a low impedance path for noise introduced from the spindle to clamp onto the supply lines - by default the high-impedance input to the microcontroller is highly sensitive to signal voltage (and therefore induced noise)... If that makes sense?

If there's any joy with this a more practical solution would be to introduce opto-couplers on the input to the controller - they'd provide good noise immunity.

EDIT:

Can you provide any details of the controller card?, even a picture?

[JeanB]

Good Morning Doddy,

Thank you for your reply. Just to inform you I am not very proficient in electronics, so it may be difficult for me to answer your questions.

My CNC works with GRBL and I use the free version of Easel at this time in order to practice……..not much practice has been done at this time.  

My switches are wired as NO and when I check the voltage across the + and - pins, I get ~2 volts and if press the micro switch, I get 0 volts. From all the information I gathered, the bottom row of pins are all to ground???? Before changing my switch wiring to shielded wires, I tried, as suggested on the internet, to add a .47µF capacitor across the micro switch………nothing.

Please find attached a picture of my board. It says: Developower V2.0

Thanks

[Doddy]

JeanB - okay, that's fine. I'm just about to head out for a last night of drunken debauchery before our government clamps down on that - I'll get some detail to you tomorrow morning.

[Kitwn]

My switches are wired as NO and when I check the voltage across the + and - pins, I get ~2 volts and if press the micro switch, I get 0 volts.
Thanks

2v strongly suggests a lack of pull-up resistors which leaves the inputs floating as Doddy has suggested. The inputs are hovering in an indeterminate state and susceptible to every light switch and cosmic particle in the vicinity. No input to any electronics should be left like this and many devices include the pull-up resistors internally, typically 10 Kohms. Some microcontrollers allow inputs to be selected as floating or pulled-up from software.

[Doddy]

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[Doddy]

2v strongly suggests a lack of pull-up resistors which leaves the inputs floating as Doddy has suggested. The inputs are hovering in an indeterminate state and susceptible to every light switch and cosmic particle in the vicinity. No input to any electronics should be left like this and many devices include the pull-up resistors internally, typically 10 Kohms. Some microcontrollers allow inputs to be selected as floating or pulled-up from software.

ATMEGA328 has an option for an internal 100k-ish pull-up.

[Doddy]

My switches are wired as NO and when I check the voltage across the + and - pins, I get ~2 volts and if press the micro switch, I get 0 volts. From all the information I gathered, the bottom row of pins are all to ground???? Before changing my switch wiring to shielded wires, I tried, as suggested on the internet, to add a .47µF capacitor across the micro switch………nothing.

Aha, thanks to Kitwn for making me realise that you're already well aware of the pin layout on the board - I'd missed that bit of your reply in my haste to reply. Hopefully you should be able to understand my earlier ramblings and ignore the bit about identifying the ground-returns on the board.