Building a CNC Controller on Mega

[navipro]

Hi Guys,
I am building a CNC controller based on Mega board. Everything is wired up and seems to work including drivers, XYZ limit switches and probe.
I have some questions re going from the prototype stage to "production"
I have followed some builds and here is how everything is connected:

Limit Switches (Normally Open)

1. X - Pin10
2. Y - Pin11
3. Z - Pin12
   Ground connected to the ground on the LEFT side of the board (near A pins)

Probe
Connected to Pin A15, ground on the RIGHT side of the board (near Pin 13)

Steppers are all grounded to the Ground on the RIGHT (near Pin13)

Questions (I am very new to microelectronics):

1. Is there a difference between ground on the RIGHT and ground on the LEFT?
2. Do i need a resistor for limit switches or probe? I read somewhere that i do and somewhere that I do not.
3. Can i add an LED light to the circuits of Probe and Limit switches to give me visual when they are completed? What is the best practice for something like that?
4. What is a good way to connect wires (AWG12-AWG22) to arduino? For now I have used "pin" wires that came in the arduino kit and have soldered thicker wires to them.

Thank you very much for your help!
Oleg

[Railroader]

@navipro

here is how everything is connected:

Please use schematics instead of poetry. Much is understandable but for the overview, the total.... Schematics please.

@navipro

Is there a difference between ground on the RIGHT and ground on the LEFT?

To be sure... What is "LEFT and RIGHT"? Most likely not.

@navipro

Do i need a resistor for limit switches

No, not if You use the built in INPUT_PULLUP and switches connected between GND and the input pin.

@navipro

Can i add an LED light to the circuits of Probe and Limit switches to give me visual when they are completed?

Schematics please. It needs precision.

@navipro

"pin" wires

They are not really reliable. Tiny, round nails into Dupont females but adding soldered wire makes it much more reliable.

[navipro]

Thank you for your response.
I will have to draw schematics tomorrow.

[horace]

@navipro

What is a good way to connect wires (AWG12-AWG22) to arduino? For now I have used "pin" wires that came in the arduino kit and have soldered thicker wires to them.

if you are moving to a production system you require better connections than dupont 'pin' cables can supply, e.g. at a minimum Mega prototyping boards with either solder or screw connections
if you do a web search for arduino mega prototyping board you will get plenty of links

you should probably be looking at a industrial quality Arduino, e.g. do a web search for industrial arduino mega

depending on numbers of devices to be made implement your own PCB

[jhaine]

The inbuilt pullups are quite high value, it would be wise to supplement them with say 1k ones to minimise noise pickup. You dont say how big the steppers are but very often in cnc machines opto isolators are used between the controller and the drives to obviate electrical noise getting into the processor from the steppers and spindle motor.

[johnwasser]

@navipro

I am building a CNC controller based on Mega board.

Is there some reason you can't use an existing CNC controller shield like a RAMPS 1.4/1.5/1.6 board?
https://www.aliexpress.us/item/2251832855205950.html

[navipro]

@Railroader

Please use schematics instead of poetry.

Here is my (rather poor) attempt as schematics.

[navipro]

Number of devices will be 1. I just like things to be tidy and reliable, even though it is a hobby router.
Do you mean one like this:

Or one like this:

[navipro]

@johnwasser

Is there some reason you can't use an existing CNC controller shield like a RAMPS 1.4/1.5/1.6 board?

I am very new to electronics and to CNCs in general, so I do feel a bit overwhelmed.
My understanding of RAMPS was that they already come with the stepper drivers. My motors pull 3amps, so I have decided to go with external drivers connected directly to the Arduino. I felt that it would be simpler solution.

[jhaine]

Could you tell us more about the steppers, drivers and machine? If you really are going to run the motors at 3A that implies quite a beefy machine. What supply voltage to the drivers and what drivers are you using? Do they have opto isolated inputs already? What motion control software, GRBL for example, or are you hoping to roll your own?

Looking at your picture you must be using GRBL or a derivative I guess. Limit and estop switches are best NC, that was if a wire drops off it fails safe.

[navipro]

Yes of course.
The machine is an Ultimate Bee from Buulkman3D:
ULTIMATE Bee CNC Router Machine Full Kit – Ball Screw Quiet Transmission – BULK-MAN 3D (bulkman3d.com)
It came with CNC Controller (CNC xProV5) which was DOA. So they want to ship me a new one but it will take 3 month. So i have decided taht instead I will build my own and learn few things in the process.
So steppers are NEMA23s,

I know they are max rated at 3A, so i am running them at 2.2.

Drivers are TB6600

I am sticking with GRBL for now. Even though i am quite familiar with programming in general, I have never programmed arduino, so taking the path of least resistance.

@jhaine

Do they have opto isolated inputs already?

Yes, they do.

@jhaine

Limit and estop switches are best NC, that was if a wire drops off it fails safe.

I agree, but I had a lot of false positives with NC, so i have switched to NO. Seems to be ok for limited testing i did.

I have 24V power supply