Z axis diving with mach3

[lamoule74]

Hey people,

We are on our way to finish a CNC plasma cutter with a boildermaker.

Mach3 R3.043.066 is used to controll the system and we are using a THC150 for the height control.

When launching the job, the Z axis got a problem: it diving linearly until touching the plate.
On Mach3, when we launch the job we can visulizing the heigh constant, then at the end we observe the Z value decremented at once (but we can see it happens continually while cutting).
Like the Z motor needs to be calibrate or corrected by an offset or something like this.

The fact is it work on manual mode.

Is anybody recognize this issue?
Do you have any idea what's happening there?

Please let me now if you can help me.
cheers.

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[RCaffin]

First thing to do is to switch to the last recognised good version: Mach3 R3.043.062 (062, not 066)

Otherwise, it sounds like a massive noise problem, or maybe a wiring problem.

Cheers
Roger

[lamoule74]

First thing to do is to switch to the last recognised good version: Mach3 R3.043.062 (062, not 066)

Otherwise, it sounds like a massive noise problem, or maybe a wiring problem.

Cheers
Roger

We've already tested with 062... Same problem.

We also went over the wiring: we put some shielded cable, nothing changed.
The wiring seems to be OK.

[RCaffin]

I will stick my neck out and repeat: that could be a serious noise problem.
However, I see that it works OK in manual mode. That means that the wiring may be OK, without a noise problem.

General comment: there is a huger amount of system detail you have not supplied, and that makes diagnosis difficult.

So, other causes?
One is that you may have the Active State for the Z axis Step wrong. This can lead to the Z axis creeping as a Step is missed at each change in Dir. In detail, there is a problem with the timing overlap between DIR changes and Step pulses. Try changing the Active State in Mach3.

Another problem may be that the Z axis is a shade too heavy for the Stepper motor driving it, at least at speed. If dropping both the acceleration and the max speed on the Z axis solves the problem, that is a clue. You could use a bigger stepper motor or a higher power supply voltage to that motor, or put in a toothed belt reduction between the motor and the Z axis. (This assumes a stepper motor rather than a servo motor.)

Cheers
Roger

[lamoule74]

I will stick my neck out and repeat: that could be a serious noise problem.

Np Bob,
of course you are giving suppositions, we are both trying to figure out what's happening.
And thank you for that.

General comment: there is a huger amount of system detail you have not supplied, and that makes diagnosis difficult.

Tell me what details are missing, I could give you more informations.
I can also give you a video I made for Proma's support.

One is that you may have the Active State for the Z axis Step wrong. This can lead to the Z axis creeping as a Step is missed at each change in Dir. In detail, there is a problem with the timing overlap between DIR changes and Step pulses. Try changing the Active State in Mach3.

I'm sorry, I'm not sure to understand what do you mean by "Active State for the Z axis Step wrong" ?
Could you please indicates me where this could be changed ? (which menu)

Another problem may be that the Z axis is a shade too heavy for the Stepper motor driving it, at least at speed. If dropping both the acceleration and the max speed on the Z axis solves the problem, that is a clue. You could use a bigger stepper motor or a higher power supply voltage to that motor, or put in a toothed belt reduction between the motor and the Z axis. (This assumes a stepper motor rather than a servo motor.)

Yep, I thought about that...
We augmented the power on motor and it seems to be way better: they are less straining.
However the problem is persisting...
I wonder if there were a "soft" option in Mach3 to compensate the weight ?
All axis are stepper motors : NEMA34 / 7 A / 36 V


Cheers

[RCaffin]

Tell me what details are missing, I could give you more informations.
What PC, what OS?
What interface? What BoB, What pulse engine if any, or LPT?
What max pulse frequency for G0?
What stepper motors, what stepper driver, what power supply?
Note that the 36 V for the stepper is almost completely irrelevant. What max current do you allow?
Almost everything matters.

Active State:
Config/Ports&Pins/Motor Outputs/DIR Lo Active

Cheers
Roger

[lamoule74]

PC: acer aspire; intel celeron J4025; RAM: 8 GB
OS: windows 10 / 64 bit
interface: mach3.fr
BoB: I don't know what is a "BoB"...
pulse engine or LPT: it's an Ethernet communication
max pulse freq. for G0: I don't know where I find this information, do you ? I suppose it's set by default...
ref des moteurs: NEMA34; 12 Nm; 400W : 215×115×50 mm
driver: DQ860MA
power supply for steppers: 36 V DC +/- 10% adjustable with potentiometer
maximum current allowed: 11A

We also changed the THC: Zetastar THC Aqtronic

About the motor, it's maybe uncommon fo your habits but I've seen many things in terms of voltage in my engineer job.
Nothing surprises me now...

[RCaffin]

driver: DQ860MA
power supply for steppers: 36 V DC
The DQ860MA is rated up to 80 VDC. 36 V is far too low.
I suggest doubling the supply to 72 VDC (really). Set the current limit to something like 5 A to start, although you may want to go a little higher. Check the motor specs for that.

It sounds as though there is an ESS at the end of the ethernet maybe? If so, good.

BoB: Break Out Board. It goes between the ESS and the outside world, and is essential.

Cheers
Roger

[lamoule74]

Hey Bob,

The boilermaker gave me a picture of the motor, eventually. (I'm not often at his workshop)
this is the reference :
85bygh450c-012b

I found this link not sur this is this manufacturer:
https://www.promoco-motors.com/produ...H%20Series.pdf
Surprisely it's not written 36 V at all...
I can read 5,7 V
But probably you talk about the driver's voltage which is converted (regulated).
I'm a bit confused.
Can you give me your opinion?

[I]
It sounds as though there is an ESS at the end of the ethernet maybe? If so, good.

BoB: Break Out Board. It goes between the ESS and the outside world, and is essential.
Roger

Another acronym. erf

So as I could read, the ESS is for Ethernet SmoothStepper ?
I'm trying to figure out step by step the name and the interlinking of every elements, this is new for me. Sorry for that...
I think the board does everything, but I should take a look more closer to what he wired at this point.

[RCaffin]

Actually, as far as the motor is concerned, what matters is the current, NOT the voltage.
The reason for the high voltage on the driver is to get a smart (fast) change in current, which gives you a lot more power.
You need to find a good tutorial on stepper motors and drivers. I don't have one to hand.

Yes about the ESS. If you do keep pushing and learning, you will end up with a very good body of knowledge: one which is never a handicap when it comes to discussions about salary. You should look at the Warp9 website and at the Gecko website for tutorials.

Cheers
Roger

[dazp1976]

Actually, as far as the motor is concerned, what matters is the current, NOT the voltage.
The reason for the high voltage on the driver is to get a smart (fast) change in current, which gives you a lot more power.
You need to find a good tutorial on stepper motors and drivers. I don't have one to hand.

Yes about the ESS. If you do keep pushing and learning, you will end up with a very good body of knowledge: one which is never a handicap when it comes to discussions about salary. You should look at the Warp9 website and at the Gecko website for tutorials.

Cheers
Roger

When I see 'nema34 12nm' mentioned anywhere I always shake my head.
OP do what I did.... Bin it!.
Get one that's half that and run that dm860 on 72v.
They're fairly cheap on Aliexpress for a switched psu.

I done it and have zero regrets. In fact I use DM860 with nema24 on 60v x,y, and DM860T with nema34 on 80v Z.
I have not found its speed or accel limit yet, so far its rapid is 3750mm/min and accel is at 2000. That's all I need for now. (mill).
36v barely saw half that.