Hello i have encountered a strange issue with my MPCNC (old version).
I was already working with it and was able to cut some first experiments by manually setting the reference point, but when connecting a touchplate its showing strange behaviour with the motors.
I have connected the SCL form the CNC-shield with my touchplate and tried connecting the ground from the shield to the case (!) of my router. Now for the crazy part: When holding the GND cable against the case of the router the steppers change their noise and also sometimes move a bit.
There should in no way be any connection between steppers and router, i do not even control the router via software, its so far just pluged into the same socket as the arduino and manually turned on by its original switch.
An idea could be that its because i used cheap wires for connecting the steppers, and that it is caused by bad shielding. Also i think connecting to the case of the router might not be the same as connecting to the cutting bit via clamps.
Has anyone had such issues? What can i try out to gain more information?
This is my setup (think its the basic most common build):
Arduino UNO (Clone but working fine)
CNC Shield V3
DRV8825 Drivers
Nema 17 steppers
12 V 5A Power supply through the Shield
Router: Makita RT0700c (standard handheld router, not modified)
Hey thanks for the quick response,
Router is plugged in but not running. Shield powersource and router are both connected to the same power strip, so they share their GND through it i guess. Even if they share the ground that would not explain the reaction coming from the motors in my mind.
One Information i can also add is that all motors are affected not single ones.
You are right, the best place to attach the ground connection to is the cutter bit using a crocodile clip, the case of the router may not have a perfect DC coupling to the bit through the bearings and motor shaft.
Do you get the same problem with the motors moving if you just short SCL to the adjacent ground pin on the shield?
Holding the grounding wire directly against the Touchplate thats connected to SCL provides a signal in Estlcam and also does not affect the motors. So that works as it should.
However once the router is put into play things go crazy and it also does not make a difference if i attach the grounding wire to the casing or the cutter bit.
Whats also important is that the SCL does not have anything to do with it it seems. The problem occurs once the grounding wire is attached to the router. The Touchplate is just laying there connected to the SCL pin, but not in touch with any other parts.
Am not home right now, but let my brother test out what happens when the router is not plugged in, and in that case it works just the way it should. So SCL to touchplate and ground to bit or casing creates a signal when the touchplate and cutting bit touch.
Have not yet tried it with connecting the router to a different socket, but also would not like to have this as my standard setup.
I did put an emergency stop button into the wire of the power strip, so that i can cut power to everything, if shit hits the fan. Think its quite nice and would like to keep it. Also would not like having to lay down two cables because the machine is moved a lot.
@Britboard looking at my problem does this fit to an earth leakage? If so, the what should be my next step in order to solve the issue?
My first question is are you electrically qualified, because it sounds to me like the router you are using has got some insulation issues or the power cords or main supply etc have a fault I.E. NO EARTH. This means the router is unprotected and could give you a nasty electrical shock if you touch the body if it has an insulation failure. I would advise you to get everything checked by a qualified electrician before you proceed any further. It is not a fault with your MPCNC the problem lies elsewhere and as such the only advice i can give ongoing is what i have said above. The dangers of electrocution are real if my instincts as a qualified electrician are correct. Be safe
Understand your concern, and will be carefull. I am not a trained electrician but can quarantee, that i wired the emergency button correctly as i checked it many times and followed instructions.
Reading your answer i get the idea that since I bought a used router i should check if the cable was changed or reatached in a bad way.
Checked the router and everything looks well conected and quite new.
Have the feeling, that my power supply might be the issue.
I have a 24 V 5A laying around that i could test with. The CNC Shield takes 12 to 24 V so that should work. Do i have to adjust anything before plugging it in? For example the variable resistors on the drivers, do i need to readjust them before switching to 24 volts?
I had the same issue - when connecting the router to GND the axis are moving a little bit.
I fixed this issue by adding a simple ferrit filter to the cable which is connected to the router.
