Homing sensors not working (properly) + laserhead moving weirdly (video)

Machine: I have a 6040 (600mm x 400mm) Chinese machine with M2 Nano board that I just replaced with the Cohesion3D board.
Board: Actually Cohesion 3D
Firmware: Smoothie

Hi @Cohesion3D , everyone,

I finally received the new Cohesion board and sadly, it seems I have the same issue as our dear friend Serge (and others). I’ll try to be as thorough as possible and post as many photos as I’d like to avoid losing both of our time. Please bear with me as I’m no tech guy. I merely fiddle with this.

All lights are good:
L1 is green
L2 is blinking
L3 is blinking
3vs3 is green
VMOT is red

Main issue is the homing sensors. They seems not to work properly. They seem disconnect. The laser head won’t stop to the homing point (which is top left in my case). With the previous M2 nano board, these homing sensors were lighted up with a red light. No more with the Cohesion board.

In Lightburn: I set up the machine with 600 (x) and 400 (y). Origin front left

In config file on SD card: alpha_max 600, beta_max 400, alpha_max travel 600, beta_max travel 600
Here is the parts I changed:

config.txt

alpha and beta motor current to 1 amp (didn’t change the seek rate nor acceleration)

Endstops

endstops_enable true # the endstop module is enabled by default and can be disabled here
#corexy_homing false # set to true if homing on a hbot or corexy
alpha_min_endstop 1.24^ # add a ! to invert if endstop is NO connected to ground
alpha_max_endstop 1.25^ # NOTE set to nc if this is not installed
alpha_homing_direction home_to_min # or set to home_to_max and set alpha_max
alpha_min 0 # this gets loaded after homing when home_to_min is set
alpha_max 600 # this gets loaded after homing when home_to_max is set
beta_min_endstop 1.26^ #
beta_max_endstop 1.27^ #
beta_homing_direction home_to_max #
beta_min 0 #
beta_max 400 #
gamma_min_endstop 1.28^ #
gamma_max_endstop 1.29^ #
gamma_homing_direction home_to_min #
gamma_min 0 #
gamma_max 200 #

alpha_max_travel 600 # max travel in mm for alpha/X axis when homing
beta_max_travel 600 # max travel in mm for beta/Y axis when homing
gamma_max_travel 500 # max travel in mm for gamma/Z axis when homing

Here is the result with the M119 command on Lightburn, same result with a metallic piece on the X and Y sensors:

M119
X_min:1 Y_max:1 Z_min:1 pins- (X)P1.24:1 (X)P1.25:1 (Y)P1.26:1 (Y)P1.27:1 (Z)P1.28:1 (Z)P1.29:1
ok
ok

Here come the pictures, starting with the old M2 as reference. As you can see, there is this 2-pin green-brown cable wired to the main power supply. This cable cannot be connected to the Cohesion board:


Here are general picturesFYI:



Here come the pictures avec the installation of the new Cohesion board:


EDIT: I changed the motor current to 1 amp and it seems to have solve the stuttering weird noise. But I still had to invert the X and Y, that’s weird. Any idea what I should do ?

Second issue at hand:
I had to invert the X and Y cable on the Cohesion board because when moving the laserhead on Lightburn, everything was inverted. So it did solve this issue but… when moving the laserhead with the arrows on Lightburn, it makes half the time a weird and worrying noise. See below. What might be the issue? Do I need extra changes on the config file to make it work properly?

Is this issue might be resolved while changing the settings below? Is this related?

  • Increasing the motor currents in the config file by 0.2 amps at a time will help dial it in. The board’s per driver max is 1.2 amps. Do not exceed the stepper motor max. Ensure the motors are not overheating after increasing.
  • Decreasing the acceleration will help slow down the cornering speed.
  • Decreasing the seek rate will help slow the moves between cuts.

Video of the laserhead moving (sound important):

Part of a possible solution for the homing sensors:
Could I use these switches as replacement with 0,5mm² (22awg) cable ?


To conclude:

  • I would appreciate a solution as to what to do with the wiring, what to change, what to check, what I did wrong and if no solution, a quick tutorial as how to change the switches (the kind of switch you’re selling aren’t compatible with my machine -> the laserhead can’t touch the switch, it’s too small.

Thank you for your help…

Yes, those switches would work fine with that cable. I myself prefer the mechanical limit switches.

Thank you for your answer. Yes, I would also prefer proper mechanical limit switches but it seems complicated to find in Belgium.

Would that be better?

Those would also work.

Here’s the quick answers:

Please do not rewire or replace anything on your machine, we will figure this out.

This should be the wires to fire the laser. We can connect them to screw terminals on the C3D board later.

Applying the C3D sticker is a critical step in the installation process :slight_smile:

Please trace and show me where the brown wires from the homing sensors are going to.

First, did you do this correctly?

I would also recommend watching this:

Bonsoir Adrien, comme toi même problème je voudrai bien changer mes capteurs,ci tu as un branchement je suis preneur car mes voyants ne s’allument toujours pas Merci @ ++++ Serge

Bonsoir Adrien, comme toi même problème je voudrai bien changer mes capteurs,ci tu as un branchement je suis preneur car mes voyants ne s’allument toujours pas

Hi @Cohesion3D,
Thanks for your quick answer.

First, did you do this correctly?

I did, front left origin, 400x600 in Lightburn and config file. While inverting X and Y cables, all seems fine (need to test again once I got the sensors working). Inexplicable.

Applying the C3D sticker is a critical step in the installation process :slight_smile:

Applying the C3D sticker is a critical step in the installation process

Exactly, I wasn’t sure it would have worked properly without it.

Please trace and show me where the brown wires from the homing sensors are going to.

Both brown cables coming from both sensors are connected to the first pin

I would also recommend watching this:

Been watching this a few times already now. The only thing it’s missing is a value for seek rate and acceleration. I have no idea what would be a reasonable value.

I’m not modifying anything in the machine in the meantime.

Salut, oui on va essayer de trouver une solution.

Adrien: Can you please tell Serge that we are figuring this out and that he does not need to return the board to me. Thank you.

ils me disent de faire la manip M119 mais je n’ai pas de voyants éclairés comment faire ce contrôle et chaque foi ils me le redemande ,je ne peu le faire je tourne en rond @ +++

@AMATO Ray de Cohesion te fait savoir qu’on va trouver une solution et que tu ne dois absolument pas retourner le produit chez lui.

@Cohesion3D
Do you think rewiring the brown cable to the second pin (laser ground) instead of the first pin would be a good idea ?

That first pin would be 24v. Can you trace where the wire in question goes to and show me where the other end of it is?

Like I said, the brown cable from both sensors is connected to the first pin and coming straight from the sensors. But I know you like videos, so I made one specially for you:

Do you have by any chance the beginning of a solution I might try during this week-end?

I want to find the source of the voltage. What I meant, was, it looks like there are 2 wires in that first pin of the plug, the brown wire and a black wire, is this correct? Where does the black wire go to?

You’re totally right @Cohesion3D
This black cable from pin-1 is going straight to what I suppose is a power supply in the 24v slot.
That would mean that the brown cable is to power the sensors? Well, it’s way above my knowledge…

I’ve found this documentation for my sensors (Sn04-n2)
Does that help for the wiring?

You can cut the brown wire going to to the power plug and connect it to the board’s 24v supply. You can access it from the screw terminal in the upper left corner of the board.