Help please. Dip switches and mach 3 settings

[Radu_Andrei]

Hi.
Regarding the random shut down of the pc, it was not the cpu or the Bios battery, nor the ram memory as I suspected, but the ssd drive and the power supply. Only after replacing both, it worked again.
And yet, after 4 consecutive carvings (apx 6 hours each) done without any kind of problem, on carving number five and six, I've got 2 strange errors.

First error is something that occured once in the past, but went away by its own, and that is that at some point during the finishing cut (ballnose), the z axis goes apx 5mm up (most of the time) or down and continues to cut the rest of the code. If it is up, I can come back to that point and redo the cut and fix it, but if it is down, it just ruins the whole thing. If I remember right, Rob mentioned a lose wire to be a potential cause for these, but I checked all wiring and it is all good. Besides, running the same gcode one more time, it works without this error. Seems more like a mach 3 error, maybe some noise from a misterious source.

Second error is that sometimes, the roughing cut does not fit the finishing cut. Like the first cut, took away to much material in some places. These seemed to get fixed by doing the project again or even as simple as recalculating the toolpath in artcam. Seems an artcam error but I am not sure. Maybe someone knows better.

The only things that changed to the machine is that I finaly figured out how to control the spindle speed via mach3 (pwm). It control the speed fine but when I turn on the whole thing, a relay on the bob goes on and off, like a clock, and this translates as a small rotation of the spindle each time it clicks. Moving the cnc via the pc keyboard when this clicking is on, cause small stalls on all axis. Pressing reset a few times in mach 3 seems to stop the clicking and then everything works great.
It can work without error for many hours or days, and then at some point, while running, I can hear the cnc changing its sound, and moving the z axis 5 mm above and continues to cut. Going back a few hundred or thousand lines and runing again the gcode, it works fine. It is like a temporary source of noise, but I have no clue from what causes it. I could not relate it to weather, or mains power, or time of the day, or gcode.

The only thing that it is clear is that the relay clicking started after setting the pwm spindle speed control, but not at that exact time, a few days later.

Like many other times in the past, I do not know what to do.

[dazp1976]

Hi.


The only thing that it is clear is that the relay clicking started after setting the pwm spindle speed control, but not at that exact time, a few days later.

Like many other times in the past, I do not know what to do.

One thing can say on this is: Don't turn on any of your control systems until you have Mach started up and in control. This prevents any of the ancillary components like spindle and cooling firing up on booting of the PC.

[cropwell]

Co-incidentally, while I was thinking about a reply during a cut, my Z axis limit switch wire caught, pulled and broke and tripped the limits. Fortunately it was a short job and after disabling the limits, I reran the job successfully. I now have that problem to attend to.

Your problem still sounds like an intermittent disconnect to your Z motor. I don't know what wires you used, but you need high flexibility wires which have many (32 for instance) strands in each conductor and flexible rubber insulation. Another consideration is the bend radius, which must be as large as practicable. The wires to the Z motor move around a lot more than any other stepper.

Also look at your solder joints. Wire at these points become embrittled and any vibration or movement can fracture them. I have all the wires to my motors fixed down with P clips to eliminate movement. Bad solder joints can be notoriously difficult to spot.

Relay clicking ? Can you give us a wiring diagram for your PWM connection? The relay can be disabled by an on board jumper, if you are not using the contacts. My PWM controller uses the BoB PWM output and Port 1 Pin 17 (Normally B axis Direction signal).

[Radu_Andrei]

dasp1976. My habit is to turn on the pc, then mach3, then the contactor for the motors, then the key for the spindle. So, I think I am doing it as you indicate.

cropwell. The cables I use can be found her.e https://electroshops.ro/cabluri/cabluri-ecranate/liycy/, I used 3x0.75mm for limits, 4x1.5mm for motors, and 4x2.5mm for spindle all shielded. There is no soldering, just terminal blocks. No screw has come loose. I checked. I would consider the disconnect option, if it was not accompanied by a strage sound in motors, while the error occurs. Also, a cable would cause a persistent problem, in my humble opinion.

I think the relay that is clicking is the one that goes on in order to start the spindle. Here is what I did https://rawcnc.com/how-to-control-sp...other-inverter. My settings are the same with the only difference that I set the PWMBase Freq to 100 instead of 1000.

Finished another carving today, without any kind of problem., but I cannot trust this machine yet, and I am reluctant taking any large orders from customers as I am never sure what hapens next and if I can deliver in time.

[cropwell]

OK - your reference to PWM threw me a little as you have connected up according to rawcnc link.

This is using 0-10v analogue control on the right hand side of the BoB in the link. This may be derived on the BoB from Mach3 PWM output which is presented on the PWM terminal of the BoB from the pin 1 output of Mach3. The on/off spindle relay is used in your case. My spindle speed control is via a SuperPID device http://www.vhipe.com/product-private/index.htm as I have a Kress router on my small machine.

The strange sound you refer to in the motors could be a result of an intermittent disconnected winding as only one coil is being energised and with the change of direction of flux it would just buzz at the speed of the driver pulses.

[Radu_Andrei]

It may very well be as you say.
On one job for example, it cut fine for half the work, then the z axis moved down 5mm and continued to cut a quarter of the work, then it got back up to finish the work at the same level. I was not in the workshop when it did this, but since that, I stay around the cnc for the time of the cut. Not very convenient, but hey, it gets the job done for the time being.
It seems like tis pwm setting creates some noise now and then, as the symptoms of the problem look a lot like electrcial noise. Still, I cannot tie this noise to anything. Seems random at the moment.

I don't know what to fix or change yet, so I'll continue to cut and take notes of future strange events, maybe I can pinpoint the cause. I'll update the post when anything new comes up.

The strange sound, to my best ability to explain, is like the motor reduces the speed (low tone) for just a sec (when it loses 5mm), but there is no speed reduction in the gcode. It seems (but I am not sure at all), that this event occurs when the z axis moves up (to safe z).

Meanwhile, thank you. :)

[cropwell]

Here is a video of a phase disconnection in a running stepper.

https://www.dropbox.com/s/add4ruae38...P0004.AVI?dl=0

[Radu_Andrei]

Thank you for taking the time to do the video.
The sound is very harsh and different from what happens in my case, but I'll check all conection again anyway. Also keep in mind the driver option.
I will try to capture a video with the events for further explanation.

Have a nice weekend. :)