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View Full Version : The Dreaded X axis stepper error using UC400ETH and UCCNC !!!



dachopper
25-07-2017, 06:51 PM
Hi guys,

Well, it's still there.... After changing from Gecko dive to AM882 drivers, I am still getting random X and Z this time, faults, as in the tool has missed 5 to 6 cm of travel in an instant.

Ran for 55 minutes doing a constant Z level face, with long straight lines, no errors.

Changed to a parallel operation, with constant Z changing, constant Y position every 3 seconds then move 1mm, and constant X reversing left to right while Z up and down.

The error that occurred within 5 minutes of the new operation starting, ended up shifting my X position by 70mm, AND shifting my Z up by 3mm - no fault detected by AM882 because speed too low for stall detection.... or because fault was not a stall.

Thought that the X/Z error was caused by a jam and motor loosing torque after overheating ( which still may have something to do with it ) So I started Parallel again while motor was boiling hot and pushed with about 40kgs force and was utterly unable to cause any kind of jam, let alone 70mm of jam.

Re-homed position, reduced speed by 50% and ran operation for 25 minutes , and through the previous anomily without error ( not a G-Code error ).

So now I'm thinking I have only ever had this error when running parallel operations with changing Z values..... Could there be something happening momentarily with the motion controller getting overloaded from all the commands and it be responsible?

Assuming this is not a lack of stepper power, or a machine jam related error then what else could cause it to jam at higher speed, but seemingly not at 50% speed?

Nick

Lee Roberts
25-07-2017, 07:42 PM
motion controller...

Good question, what motion controller are you using? Do you have a USB breakout board in play?


what else could cause it to jam...

Good question, are you 100% positive everything is mechanically sound with the machine?

dachopper
25-07-2017, 08:14 PM
UC400 ETH controller, UCCNC software

I don't know, I can turn the ball screws by hand from end to end..... what more could cause the X axis to seemingly bind, not get noticed by the 822, and then immediately unbind in reverse direction?

Next step is GOPRO an entire cut in the air, and see if it jams unloaded under inertia or no jam and program telling it to move?

Doddy
25-07-2017, 09:56 PM
Have you checked the pulse width from the UC400 ETH?, I don't know how but I've noticed its an option in the UCCNC software. The AM882 needs >2.5us for reliable operation. Worth a look?

ptjw7uk
26-07-2017, 12:08 AM
Does the power supply have enough output!

Peter

Ger21
26-07-2017, 01:25 AM
Have you checked the pulse width from the UC400 ETH?, I don't know how but I've noticed its an option in the UCCNC software. The AM882 needs >2.5us for reliable operation. Worth a look?

Pulse width is not an option. It's a function of the kernel frequency. I believe that you need to use 200Khz or less to get 2.5us pulse width.

dachopper
26-07-2017, 04:32 AM
Using 50 khz , .1 sec com buffer, and 300 line look ahead

A_Camera
26-07-2017, 10:05 AM
Driver PSU voltage: ???
Micro stepping: ???
Stepper current: ???
Speed and acceleration: ???

The AM882 seems to be pretty complex compared with the traditional analogue drivers, are you sure it is been configured right, according to the manual?
Have you checked the signal levels at the AM882 end? How about wiring?

A_Camera
26-07-2017, 10:07 AM
Using 50 khz , .1 sec com buffer, and 300 line look ahead

No benefit in using 50kHz and it is too low if you have a fast machine. Raise it to 200kHz.

Ger21
26-07-2017, 01:10 PM
What's the benefit of 200Khz?
50Khz gives you a longer pulse width, which can be a benefit with some drives.

The fact that he's had this issue with both Geckos and Leadshines, means it's probably not the drives.

That would point to maybe the power supply, an issue with accel/velocity settings, or a mechanical issue.

You said the motors are very hot? What are the motor specs, and what do you have the drive current set at?

routercnc
26-07-2017, 01:30 PM
You said the motors are very hot? What are the motor specs, and what do you have the drive current set at?

My thoughts exactly. I've machined lots of parts often taking an hour or more and motors are never boiling hot. Warm to the touch is the hottest they get. Try turning the current down.
My understanding is that voltage is doing the work and turning down the current will help the other parts of the chain such as drivers and psi. If they are browning out under the load that is easily on the list of lost steps suspects.

dachopper
26-07-2017, 04:29 PM
Hi guys... Sooooooooo angry right now !!!!!!!!!!!!!

I just video'd the problem for the first time, it was a vertical travel move, with speed turned down to 50% of my tools recommended speed.

After 8 minutes, the tool lifted vertically while unloaded with a slow retract speed, and the Z height travel jammed for 1/2 a second just before getting to full retract height. then plunged into the part. on the next down shift. It wasn't accelerating, it was at travel speed when it jammed on nothing

The previous other error was not caused by the Z axis, as it was an X axis shift, that also must have had to jam and remain in mid air - and be unloaded for 3-4 seconds wile being sent an X command but remaining Dead still in the X axis, with the Z axis moving up making the tool cut vertically in mid air.

Current Peak is set to 3.5A with Pro tuner in the AM882

Stall detect will not function as my cut speeds are low while I try to figure out what is causing these issues

Motors are NEMA23 381oz/in 3.5A Single Shaft Stepper Motor KL23H2100-35-4A, 0.9 degree.

Power supply is PS-10N68 - 1000W 68V Power Supply running 4 of the above steppers, ( two of the motors would have been on 50% current hold ) when the other motor stalled also.

The final thing is that I tried as hard as I physically could to get the Z and X axis to jam, and i just physically cannot, even with the motors hot............ any ideas?

Remember, they both effectively jammed at travel speed, basically under no load, .... but y?

m_c
26-07-2017, 05:07 PM
Is there anything still original from when the problem first appeared?

What BOB are you using?
I'm wondering if it's a faulty BOB causing issues with step/dir outputs.

dachopper
26-07-2017, 05:47 PM
The only original parts are UC400ETH, UCCNC + PC software and hardware, Spindle, motors + wiring..

More clues, just had fault number 3 for today on video, I had everything running, but no drill bit in the spindle, ( All electrics on and running, spindle was turning but with no BIT. This time the X axis jammed during a left to right travel movement. just after reaching retract height, under no load. AM882 stall detect SHOULD have picked up this stall, it was at 450rpm, but it didn't........ some kind of electrical interference?

Did another RUN everything turned on again, but this time the spindle freewheeling ( inverter powered but no power to spindle ).....18 minutes later, no fault

Ok - I've now noticed that the X axis jam that happened in mid air snapped the coupling in half.

Just ordered some different spindle shielded cable - siemens proflex EMV

I do have the spindle running in the same 50mm cable carrier as the X / Y motors... would this normally be ok? I don't think I've seen a DIY machine that doesn't run this setup yet?

routercnc
26-07-2017, 08:03 PM
The only original parts are UC400ETH, UCCNC + PC software and hardware, Spindle, motors + wiring..

More clues, just had fault number 3 for today on video, I had everything running, but no drill bit in the spindle, ( All electrics on and running, spindle was turning but with no BIT. This time the X axis jammed during a left to right travel movement. just after reaching retract height, under no load. AM882 stall detect SHOULD have picked up this stall, it was at 450rpm, but it didn't........ some kind of electrical interference?

Did another RUN everything turned on again, but this time the spindle freewheeling ( inverter powered but no power to spindle ).....18 minutes later, no fault

Ill do another run with the spindle rotating, but everything else turned off..... then I can be positive somehow spindle interference is causing the dam issue.

When I got random estops awhile ago I plugged the invertor into a socket at the other end of the workshop via a 10m cable reel. No issues since.

A_Camera
27-07-2017, 10:02 AM
What's the benefit of 200Khz?
50Khz gives you a longer pulse width, which can be a benefit with some drives.

...that depends on his settings, which I still have no idea about.

50kHz means maximum 50,000 pulses per second.

So, here is my calculation for my machine:

If a motor, like most steppers, takes 200 steps/rev, using 10x micro stepping means 2,000 step pulses for one rev. The speed is 9000 mm/min which is 150mm/s. To move 150mm with my 1605 I need to turn the screw 30 times, so 30 x 2000 = 60,000 which is obviously more than 50,000 meaning that my MINIMUM should be 100kHz.

In other words, it is not possible to say if 50kHz is enough or not, that depends on his speed, screw pitch and micro stepping settings, but those questions are not answered yet, or I missed that part.


The fact that he's had this issue with both Geckos and Leadshines, means it's probably not the drives.

That would point to maybe the power supply, an issue with accel/velocity settings, or a mechanical issue.

Yes, that could be the issue as well, but even the kernel frequency if it is too low, or in fact, the current settings. Of course, if the kernel frequency is too low then lowering speed and acceleration might hide the actual issue when the solution should actually be raising the frequency. If the current is too low then acceleration and deceleration may occasionally be a problem, while at other times it may work. Can also be that it works on one axis but not another. Of course, if the PSU is not able to deliver the necessary current then that might also be an issue...


You said the motors are very hot? What are the motor specs, and what do you have the drive current set at?

I don't think motor temperature is a problem. In fact, I think most people draw the wrong conclusion, put their hands on the motor and "decide" that it is too hot, when in reality, you can't really hold your hand on anything for a longer period which is above 40-50 C. Steppers can get as hot as 60-80C so I would really not worry about that, assuming the drivers are set up right and the motors are designed for that current. In any case, "motors too hot" says nothing without stating the MEASURED temperature.

I had similar issues once and the solution was simple: raised the motor current and the kernel frequency. Problem gone immediately after and never seen it again. Of course, motors got hotter but that doesn't matter, I measured and is still well below the limit.

A_Camera
27-07-2017, 10:25 AM
The only original parts are UC400ETH, UCCNC + PC software and hardware, Spindle, motors + wiring..

More clues, just had fault number 3 for today on video, I had everything running, but no drill bit in the spindle, ( All electrics on and running, spindle was turning but with no BIT. This time the X axis jammed during a left to right travel movement. just after reaching retract height, under no load. AM882 stall detect SHOULD have picked up this stall, it was at 450rpm, but it didn't........ some kind of electrical interference?

Did another RUN everything turned on again, but this time the spindle freewheeling ( inverter powered but no power to spindle ).....18 minutes later, no fault

Ok - I've now noticed that the X axis jam that happened in mid air snapped the coupling in half.

Just ordered some different spindle shielded cable - siemens proflex EMV

I do have the spindle running in the same 50mm cable carrier as the X / Y motors... would this normally be ok? I don't think I've seen a DIY machine that doesn't run this setup yet?

Normally it is not an issue to run the spindle and stepper cables in the same cable carrier. I have done that and never ever could relate any problems to that.

Right now I think you are a bit upset and inconsistent/badly structured in your efforts to finding out what's wrong. I think it would be a good idea if you could cool down a little, accept the fact that you have many problems and try to solve them one by one. I understand that you are upset and emotional but it does not help in fault finding. Remove the spindle from the loop by completely disconnecting it from the mains. At this moment milling air is perfectly fine. No need for a spindle at all. Try to solve all the other issues first since your machine is useless as it is anyway. Describe your machine, post a few pics of major parts and technical specs and settings. Answer questions instead of asking loads of new ones in a non-structured way, because at least I have problems with understanding your actual issues, there seems to be far too many and probably not related to each other, but I don't know.

The snapped coupler may be because you are using the type which is frequently sold on eBay as "flexible coupler" and basically is just a joke and they can snap and also cause other issues, but since you don't post any pictures or video it is difficult to say what can be the problem with each issue.

m_c
27-07-2017, 05:08 PM
The thing that sticks out to me, is the seemingly random stalling. The fact the drivers never picked up the stall at speed, makes me think the problem is on the step/dir side.

Noise I wouldn't expect to cause a sustained stall. I'd expect more random lost/gained steps, with gradual loss of position, not just a sudden stall. It could be that there is some form of excess noise that is saturating the step signals, but I'd expect other noticeable issues if the noise really was that bad.

Wrong settings, I'd expect stalling during acceleration, or under cutting conditions. It is possible that at high speed the current drops due to not a high enough voltage, but the drives should detect the stall, and as the fault still occurs at reduced speed, it makes this unlikely.

Mechanical problem is not a likely cause, especially as this affects more than one axis, however it could be more than one problem. But again, the stall at speed should of been detected.

Given that other axes still seem to keep moving normally, I'd doubt a power supply issue.

One thing nobody has asked, is when the stall happens, is the affected axis motor making any noise?
If the motor had stalled, you would normally hear it cogging/vibrating. If it just stops with no noise/movement, the driver has stopped driving it.
If you're not sure what cogging sounds like, lock one of the stepper motors (holding the pulley by hand should be enough provided you're not using high torque steppers), and move the axis. You should feel and hear the motor cogging as it jumps steps.

I think the only way to find a definitive answer, would be to connect up a digital storage scope (or even a cheap logic analyser should do) and monitor the step signals of the affected axes, with the hope you manage to record the signals during a stall.

Ger21
27-07-2017, 05:48 PM
What version of UCCNC are you using, and have you been using the same version all along? Maybe try updating it?

dachopper
27-07-2017, 06:50 PM
So guys,

I am fairly confident that I have diagnosed the problem correctly.

Background - I seem to experience random jamming in the X / Z axis, where by the stepper would loose any huge amount of steps - up to 5 or 10CM of error per event.
It only happened when running parallel type operations with multiple quick Z or X axis toolpaths, or both at the same time. I can run a parallel operation in the Y direction with Fixed Z height, and have no issues whatsoever for hours, but the other direction - within 10 to 15 minutes guaranteed motorStall in Z or X

I changed the power supply from 600W switching, to 700W torroidal, to 1000W torroidal.
I tried 2 x different Gecko drive motherboards
I bought new Ethernet cabling from the laptop to ETH400
I replaced the Geckodrive with a PDMX126 + 5 x Leadshine AM882 digital stepper drivers
I ran the motors under both 3.5 Amp peak setting, and 3.5 Amp RMS setting.
I observed stalls occurring randomly 10-20 minutes in, in every single one of those tried changes
I currently have the Max speed set at 80% of motors peak torque rating, and acceleration set at 10% of the slowest acceleration speed I was able to generate an inertial induced motor stall.
I cannot physically make these motors stall no matter how hard I push / pull / sit on the gantry while it's moving, yet it still stalls mid air unloaded.

After finally videotaping 3 stall events, none of which were cause by excessive speed, loading or acceleration, and also noting the AM882 failed to detect the stall.. I then unplugged the spindle and on the first attempt got to the end of the toolpath without error ( It had failed 100% of previous attempts, within 13:20, 12:00, 9:00 and 17:00 minutes on the recorded occasions - including 2 of those where the spindle was spinning in the air, with and without a tool in, and not cutting anything during the test run but with stalls both occasions. )

Based on the above evidence, that the stalls are not occurring in the same place, or even at the same time, and I can't find any mechanical issue with the machine, It has to be an electrical problem.
It is not effecting the Y axis, and the Y axis cabling does not run anywhere near the spindle cabling, but the X and Z axis runs right next to it the entire wire length.

So, I have ordered some heavy duty VFD cabling ( siemens Protoflex EMV ) and I am also going to re-wire the Z and X stepper motor cables, with some different Foil + wire shielded, and move them to either sides of my cable tracks, with the water lines in the center.

After re-doing the cabling, that is almost the entire electronics replaced, except the ETH400, and stepper motors themselves.

My toolpath is being tested by the UC400ETH retailer, to confirm they do not see any issues from it during the parallel operation, to try rule that out also.

Should be able to test in a few weeks when new cabling arrives, Let you know how it goes.


M_C, the stalls are loud high pitched, and without any movement at all from the jammed axis while the high pitched noise is active, which is normally for the 3 - 4 seconds, or the duration of the attempted move for that axis, until commanded to hold or reverse and it unstalls at that point. I tried straight after it stalled to force it, and it was futile, I would have needed a serious tyre lever to have any chance of making a mechanically forced stall happen with these low speed / accel settings.

A_Camera
27-07-2017, 07:06 PM
So guys,

I am fairly confident that I have diagnosed the problem correctly.

Background - I seem to experience random jamming in the X / Z axis, where by the stepper would loose any huge amount of steps - up to 5 or 10CM of error per event.
It only happened when running parallel type operations with multiple quick Z or X axis toolpaths, or both at the same time. I can run a parallel operation in the Y direction with Fixed Z height, and have no issues whatsoever for hours, but the other direction - within 10 to 15 minutes guaranteed motorStall in Z or X

I changed the power supply from 600W switching, to 700W torroidal, to 1000W torroidal.
I tried 2 x different Gecko drive motherboards
I bought new Ethernet cabling from the laptop to ETH400
I replaced the Geckodrive with a PDMX126 + 5 x Leadshine AM882 digital stepper drivers
I ran the motors under both 3.5 Amp peak setting, and 3.5 Amp RMS setting.
I observed stalls occurring randomly 10-20 minutes in, in every single one of those tried changes
I currently have the Max speed set at 80% of motors peak torque rating, and acceleration set at 10% of the slowest acceleration speed I was able to generate an inertial induced motor stall.
I cannot physically make these motors stall no matter how hard I push / pull / sit on the gantry while it's moving, yet it still stalls mid air unloaded.

After finally videotaping 3 stall events, none of which were cause by excessive speed, loading or acceleration, and also noting the AM882 failed to detect the stall.. I then unplugged the spindle and on the first attempt got to the end of the toolpath without error ( It had failed 100% of previous attempts, within 13:20, 12:00, 9:00 and 17:00 minutes on the recorded occasions - including 2 of those where the spindle was spinning in the air, with and without a tool in, and not cutting anything during the test run but with stalls both occasions. )

Based on the above evidence, that the stalls are not occurring in the same place, or even at the same time, and I can't find any mechanical issue with the machine, It has to be an electrical problem.
It is not effecting the Y axis, and the Y axis cabling does not run anywhere near the spindle cabling, but the X and Z axis runs right next to it the entire wire length.

So, I have ordered some heavy duty VFD cabling ( siemens Protoflex EMV ) and I am also going to re-wire the Z and X stepper motor cables, with some different Foil + wire shielded, and move them to either sides of my cable tracks, with the water lines in the center.

After re-doing the cabling, that is almost the entire electronics replaced, except the ETH400, and stepper motors themselves.

My toolpath is being tested by the UC400ETH retailer, to confirm they do not see any issues from it during the parallel operation, to try rule that out also.

Should be able to test in a few weeks when new cabling arrives, Let you know how it goes.


M_C, the stalls are loud high pitched, and without any movement at all from the jammed axis while the high pitched noise is active, which is normally for the 3 - 4 seconds, or the duration of the attempted move for that axis, until commanded to hold or reverse and it unstalls at that point. I tried straight after it stalled to force it, and it was futile, I would have needed a serious tyre lever to have any chance of making a mechanically forced stall happen with these low speed / accel settings.

OK, so you continue to change/rebuild without knowing what actually is wrong. Maybe you will eventually fix it but without knowing what was wrong. It was waste of my time here since you are not answering any questions. Good luck.

m_c
27-07-2017, 10:20 PM
The fact the motors are still trying to move, tells us the drivers are still trying to move the motors, which leaves only two possibilities. Either there is something mechanical jamming, or there is some kind of glitch in the step pulse stream causing the motors to stall.

Where did you source the ballscrews?
Something like a bit swarf in the nut, can cause these kinds of symptoms. It just occasionally gets dragged between a ball and the screw, causing things to jam. Stop motion, swarf gets moved out the way, and things start running perfectly again. Only way to find out if this is the case, is to dismantle the nuts and clean them.

Noise could cause a glitch resulting in a sudden deceleration/acceleration, which could be enough to cause the motor to stall. However I'd still expect that amount of noise to cause other problems. Key things I'd be checking/double checking, is any shielding goes back to a star point, and you've not introduced any ground loops anywhere.

dachopper
28-07-2017, 07:55 AM
With the shielding, is that all the shielding, including spindle braid and stepper shielding together at one end on mains power earth, or just together?

dachopper
10-08-2017, 09:02 AM
Hi guys,

My suspicions were correct, the culprit is EMI coming from the spindle, but now that I have replaced all of the cables...... I need some electronically minded advice.

The spindle is leaking current to the entire machine when it is powered somehow.

Inside the 2.2KW inverter, I have the house power connected to R /T on the left for active / neutral, and Ground on the far right.

Then I have the spindle power on U/V/W in the middle.

The shielding on the spindle cable is not connected to anything at the Inverter end, but it overlaps onto the metal plug at the Spindle end - could this be the cause?

The other possible issue is that this spindle does not have an earth - aside from it's power return cable.... If I did run an earth wire attached to the spindle or aluminium Z axis block, can I just plug that into the house power earth inside the inverter box, or could that cause some kind of fault/loop?

The question is, is the charge coming from the shielding getting charged, and because it's touching the outside of the metal plug, it's then charging the machine, or the lack of a spindle frame Earth is now somehow causing the issue




22499
22500
22501

Clive S
10-08-2017, 10:20 AM
Ok First make sure the machine frame is earthed to the star point in the control box, make sure the screen on the spindle cable is earthed at one end only (solder a wire to the screen and ground it to the spindle body)

Are all your other cable screens grounded to the star point (In the control box you should have only one point where everything is grounded to)

dachopper
10-08-2017, 07:12 PM
Ok.... I disconnected the Spindle power cable braided sleeve so it is now fully insulated at both ends, and so is not physically touching the metal spindle plug either.

With the spindle turned on at 18,000 rpm, I have a 40 Volt ac signal generated, between the Spindle/Machine, and the spindle power cords' Braided Sleeve, at 9,000 hz. The machine ran without issue.

So - should I run an earth from the braided sleeve to house . power inverter earth at one end.... I don't see how this would dissipate electricity though as it's an AC signal effectively being generated by EMI.

2. I will probably run another earth wire back from the spindle to the House earth now - to stop electric shocks in the case of other failures.....

If I have the AC leaking braided sleeve earthed with the inverter / house earth, and also conect an earth from the spindle to the inverter / house earth, I could be back at square 1 as the spindle could get some of the AC?

dachopper
10-08-2017, 07:25 PM
Ok First make sure the machine frame is earthed to the star point in the control box, make sure the screen on the spindle cable is earthed at one end only (solder a wire to the screen and ground it to the spindle body)

Are all your other cable screens grounded to the star point (In the control box you should have only one point where everything is grounded to)

In the control box, I have main 220Volt house power earthed to the corner of the mounting plate, The Stepper Drivers are bolted to the plate, and the Torroidal Transformer is also bolted to the plate.
Then I have a single earth wire coming off that same corner to a small ACDC transformer, and another single wire that goes off then splits to 4 and is the AC earth for my woodchip / 2 x pond pumps and Spindle power inverter.

So I should earth the spindle + Spindle sleeve to earth in the inverter? or back to star?


From DC transformer - all that suff plugs directly into the stepper drivers etc....

m_c
10-08-2017, 11:49 PM
Try downloading some manuals for good quality VFDs to see how they recommend grounding.

Typically the screen would be connected to the earth point at the VFD. Then the VFD earth connected to the star point.
Whether the screen gets connected to the motor varies. I'd be inclined to try it with and see how things run, as having the spindle well grounded is recommended from a safety point.

Ideally you want to avoid ground loops, however sometime they're unavoidable. Having them in the screen of a power cable isn't likely to cause problems. The problems occur when you get a ground loop in signal wire screen, as that's when you start introducing noise into control circuits.

Clive S
10-08-2017, 11:51 PM
In the control box, I have main 220Volt house power earthed to the corner of the mounting plate, The Stepper Drivers are bolted to the plate, and the Torroidal Transformer is also bolted to the plate.
Then I have a single earth wire coming off that same corner to a small ACDC transformer, and another single wire that goes off then splits to 4 and is the AC earth for my woodchip / 2 x pond pumps and Spindle power inverter.

So I should earth the spindle + Spindle sleeve to earth in the inverter? or back to star?


From DC transformer - all that suff plugs directly into the stepper drivers etc....

OK some decent picture of your control box would be good.
You need to earth the screen at one end only.
Do you have screens on the stepper wiring?
Do you have the machine frame grounded?

dachopper
11-08-2017, 06:56 AM
Ok , Thanks Clive / M_C

I ended up running a separate ground from the spindle all the way back to the star, and from the sleeve all the way back , and another from the inverter power feed all the way back

The shock I was getting on the Z axis has moved to a different area of the frame ..... WTF !


I don't really understand how AC voltage is detected, but what I noticed is that I seem to have 12 Volt AC between my machine and the workshop floor, although the freq jumps. When I power up the anxillary devices, ( water pumps, spindle powered but not turning, and woodchip extractor on but not turning, the A/C jumps up to a constant 105-110 Volts 60Hz. I get a tingle touching the machine frame bearfoot after that.

Does this seem like an earth leak in the shed somewhere?

The machine frame was earthed to the same star point as the inverter / Dc transformer / spindle / spindle sleeve. I tried discnnecting it as I'm trying to figure out where the zapping is coming from.

All I know is that with the machine on and the DC steppers motoring, there is no problem and no zapping.

With the spindle relay on..... and spindle turning there was big zapping when the spindle rotated.... that is fixed , but now there is a smaller underlying zap that is on when the A/C power is on regardless if the devices are turning or not.

Should my stepper motor power sleeves also go to the same A/C ground? they are currently not connected? ( insulated both ends )

Clive S
11-08-2017, 10:22 AM
Ok First from what you have said are you sure that you have a good earth into your shop (is it actually connected)?

Where are the pictures?

It is beneficial to wire steppers with 4 core screened cable with the control box end of the screen connected to the star point.

Personally I would keep the vfd mains wiring on its own socket.
If you have grounded the screen on the spindle cable at the vfd end. then don't connect the screen at the other end.

Have you grounded the machine frame? to the star point. (the purpose of the star point is to avoid ground loops)

I take it that the electricity supplier give you an earth connection and that you are not using an earth rod in the ground.

phill05
11-08-2017, 11:07 AM
[QUOTE=dachopper;93928]



The spindle is leaking current to the entire machine when it is powered somehow.

Inside the 2.2KW inverter, I have the house power connected to R /T on the left for active / neutral, and Ground on the far right.

22499

Why is the blue Neutral wire going to a frame screw and jumping back to the R/T side? could this be the culprit.

Phill

dachopper
11-08-2017, 01:39 PM
Ok First from what you have said are you sure that you have a good earth into your shop (is it actually connected)?

Where are the pictures?

It is beneficial to wire steppers with 4 core screened cable with the control box end of the screen connected to the star point.

Personally I would keep the vfd mains wiring on its own socket.
If you have grounded the screen on the spindle cable at the vfd end. then don't connect the screen at the other end.

Have you grounded the machine frame? to the star point. (the purpose of the star point is to avoid ground loops)

I take it that the electricity supplier give you an earth connection and that you are not using an earth rod in the ground.

Hi clive....

So this is what I'm at now.

I checked all the stepper motor shielded cables, made sure they were insulated at the stepper motor end and touching nothing, then at the control box end they all go to the star point.

The VFD spindle/Z axis block is now earthed direct to the star point. ( No other frame earth, just the one on the Z block )

The VFD cable shield is earthed separately onto the same star block, and it's insulated at spindle end ( not touching the spindle )

The other AC appliances ( VFD + Wood chip motor + 2 x pumps ) are all earthed at the same star point where applicable.

On the earth side - I'm using the house common earth..... how can I test if this is faulty?


I was a little concerned about the cable shielding pushing an AC signal back into the stepper motor shielding, but it seems to be going ok, 40 minutes into a cut now

dachopper
11-08-2017, 01:42 PM
Hi Phill, it's illusion, the neutral 240 Volt connection for this VFD is active / neutral on far left, and ground far right, then 3x spindle wires in the middle ( there is no spindle ground from manufacturer)

Clive S
11-08-2017, 01:55 PM
The VFD spindle/Z axis block is now earthed direct to the star point. ( No other frame earth, just the one on the Z block )
Personally I would just earth the main frame not the Z block ( if you want to earth the Z block connect that to the main frame)


was a little concerned about the cable shielding pushing an AC signal back into the stepper motor shielding, but it seems to be going ok, 40 minutes into a cut now

Let us know how you get on.

Still no pics of the control box !!

dachopper
11-08-2017, 02:09 PM
22515
22516
22517
22518
22519

dachopper
11-08-2017, 02:11 PM
The stepper ground is temporary as I was still trying to troubleshoot

Clive S
11-08-2017, 02:31 PM
The stepper ground is temporary as I was still trying to troubleshoot

Ok It is always better to use twisted pairs for the step and dir wire from the drives to the control board just chop a cat5 cable up.

dachopper
11-08-2017, 04:08 PM
10mm x axis skip. I've now moved the vfd braid shield onto a separate ground than the stepper shielding.

If it happens again, I'll move the spindle motor shield onto th

dachopper
11-08-2017, 04:09 PM
Guess what.... all skips happening on parallel moves..... ! Strange

Clive S
11-08-2017, 04:19 PM
Guess what.... all skips happening on parallel moves..... ! Strange

I you sure that this is not binding up or overtuned

dachopper
11-08-2017, 04:28 PM
I am positive it is not mechanical, if I leave spindle turned off, it does not skip. If I turn spindle on and run job in the air, it jams under no load, and if I try to force it to jam, I can't, so it's 100% electronic interfere

Clive S
11-08-2017, 05:47 PM
Guess what.... all skips happening on parallel moves..... ! Strange

what do you mean by this

dachopper
11-08-2017, 06:40 PM
It;s the type of Cut the machine is doing when the skipping happens. Its a a sideways X movement with vertical Z at the same time, repeat x 1000

Doesn't seem to skip doing a normal constant Z level manoeuvre....

Now I must be 3.5 hours into this next cut, so far no issues.

m_c
11-08-2017, 09:46 PM
Given the 'zapping' I would be checking you do have a good earth. The normal easy test is one of those plugin testers with LEDs on, but given you're down under, I'm not sure what would be available. It's also worth running the machine at the same time as having the tester plugged into the next nearest socket, just to make sure a good earth remains with things under load.

If you don't have a good earth, then the various filtering capacitors typically found in mains connected electronics (VFDs especially), can cause a voltage build up, which will earth through the nearest thing, which can be the person in contact.
You may need to install a new earth rod, or figure out why you've got a poor earth.
(does Australian power use L,N+E, or a centre tap L,L,N/E? to get 110V and 220V?)

dachopper
12-08-2017, 03:09 PM
This is so frustrating, so I had another 4-5 skips / jams on the x and z axis doing this parallel job, so I reduced the speed, and the acceleration by 50% , still jamm, turned off the spindle, no jam. Put the spindle power plug and spindle / vfd cable earth on separate circuit ( not going through control box ) still jam.

Then I disconnected the spindle earth ( which runs inside the vfd cable so is probably a massive noise carrier, from the spindle and IE from the machine, and so far no jams.22535

This ground cable was effectively attaching the vfd noise onto the machine. Since the stepper motors are on the machine, they are then subject to the effectively AC pulse made by the VFD earth, and by the vfd cable shielding.
...


Update:
So disconnecting the VFD ground wire from the frame got me much further into the cut, infact the two medium sized parallel ops finished correctly without any issues, then I ran the really big one, it had a single skip 80% through. So now I'm thinking because the frame is now not grounded as I removed the spindle ground, I'm thinking of running a separately shielded spindle / Z block ground, to get rid of the static or whatever build up is occuring. Could Cat5 cable be useful in that scenario? I'm just trying to find a way to let the noise / static discharge without inducing any further issues...

Nick


So

m_c
12-08-2017, 08:45 PM
I think you may need to add ground wires between the various parts of the machine, to ensure everything is grounded.
I've just noticed in your photo, that you're using aluminium extrusion, which will be anodised, and anodising is a brilliant insulator.

Did you try running the machine with the VFD cable screen connected at both ends (and check that with it connected, there is continuity between the spindle body and the VFD earth point)?

dachopper
12-08-2017, 09:09 PM
Hi MC,

I measured the voltage that the shielding on the VFD cable produced when the Spindle was turned on, it's was straight to a 40 Volts AC signal, between the shielding, and the CnC frame. When I connected that shielding to the frame, the steppers went ape shi*T. Motors were stuttering and I could " hear" the motors struggling to just run normally. Now, the machine wasn't grounded at this stage, but that was the effect of attaching the noise directly onto the frame of the machine.

I then unattached that end of the shield, and tried to attached what i thought would be a suitable ground ( it was an unused wire from inside the VFD shielded cable ) Big mistake - now this wire WAS on the Earth ground at one end, running through the VFD cable, and attached to the Z axis / stepper motor mount at the other end. I think all I did, was make a big long antenna inside the VFD cable, which even though it was grounded, was helping to turn the machine into another noise generating machine.

Then I got desperate after about 5 jams in 10 minutes, so I undid the " VFD " ground wire from the spindle / Z block and this made a big difference, but now the machine is not grounded any more.

So I am going to run another two grounds, one from the machine frame to house ground ( which is the same as the start point, but from a different socket) , and another shielded cable up the cable tracks and onto the spindle/ z block, which will then go to the other house ground.

I keep reading about these star grounds, but the fact is the VFD cable is creating an AC type noise signal, and If I run that into my electronics enclosure base plate, what is stopping it going straight back up my Stepper controller shielding which is connected to the same base plate? hence I'm connecting these two at a different socket of house earth, in the hope it weakens before reaching the base plate again.

I don't think Im going to connect the VFD cable screen back up to the frame, it just seemed to make the situation far worse.

m_c
12-08-2017, 09:28 PM
The entire point of the VFD cable screen is to absorb the EMI from the VFD cables, and drain it to earth. Due the VFD cables carrying a fast switching AC signal, an AC signal will be generated in the screen.
The fact that there is a voltage present, tells me that's it not correctly grounded. And also that connecting it to the machine frame makes things worse, tells me the machine frame isn't grounded correctly. If the screen was correctly grounded, then there should be negligible voltage in it, as it should be getting drained to earth without causing any problems.

Which brings me back to my earlier question, are you sure your power supply earth is correctly earthed?

Clive S
12-08-2017, 11:26 PM
Which brings me back to my earlier question, are you sure your power supply earth is correctly earthed?This is what I mentioned several posts back but you make a good point re the anodised stuff so as M_C has said ground each part ie Z plate to gantry to machine frame to Star point

dachopper
11-09-2017, 07:40 PM
Ok - I thought I would put some closure in here..... The random X and Z axis ' jams' were 100% due to electrical interference from the spindle control wires.

I had unshielded control cable, with shieleded stepper cable

Then I tried shielded control cable but mistakingly placed the machine earth inside the Spindle power cord, and in doing so charged the entire machine up with a generated AC signal.

Then I earthed the frame + spindle + spindle shielding + stepper motor shielding seperately to house earth, and finally, no issues !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!