What is wrong with my CNC machine?

Hello.

I wonder if anyone can help me with a problem im having with my A2 CNC machine.

I am running V-Carve Pro and Mach3 on a laptop supplied by the company.

Problem is, the machine seems to randomly go berzerk and start cutting in the wrong direction. I doesn't always do it, but its a major annoyance when its half way through a job and decides to go off course. (and a total waste of materials)

I have spoken to the manufactures and they changed some settings (Speed, velocity) and it seemed ok for a while, but is doing it again.

Today I cut 3 pockets, it did the first 2 fine, then when moving over to the 3rd one, it made a different noise and started cutting it it in totally the wrong direction.

I get the impression the company doe'snt want to know, so thought I'd ask here for any help as I have no faith in it doing what I bought it for.


Thanks in advance.

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Today I cut 3 pockets, it did the first 2 fine, then when moving over to the 3rd one, it made a different noise and started cutting it it in totally the wrong direction.

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Sounds like that "different noise" was the stepper(s) stalling and losing position.
Could be a lot of different things causing this.

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Problem is, the machine seems to randomly go berzerk and start cutting in the wrong direction.

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Do you always here the stalling noise when this happens?


Make sure that all moving components are properly lubricated, and there is no binding anywhere in the machine.

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Originally Posted by ger21

Sounds like that "different noise" was the stepper(s) stalling and losing position.
Could be a lot of different things causing this.




Do you always here the stalling noise when this happens?


Make sure that all moving components are properly lubricated, and there is no binding anywhere in the machine.

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Thanks for reply.

I lubricated the machine as advised in manual.

Did a test with the spindle (Kress) turned off, and 4cm above work area and it does it fine. Its cutting MDF 3mm at a time at 20.000rpm like butter, so its not stressing it.

Try reducing the cutting speed. My previous machine would run 60ipm over air, but I would usually cut 40ipm for the roughing passes and 30ipm for the final pass.

Stepper motors have less torque at high speed, so it doesn't take much to stall them when they are operating near their upper limit.

Steve

If it works well and doesn't fault unless the spindle's on, that indicates electrical noise interference from the spindle. Check your grounds - improper grounding is usually what causes this sort of thing. If the grounds are all okay, then consider shielding the spindle leads with braided conductive wire, connected at one end only.

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Originally Posted by awerby

If it works well and doesn't fault unless the spindle's on, that indicates electrical noise interference from the spindle. Check your grounds - improper grounding is usually what causes this sort of thing. If the grounds are all okay, then consider shielding the spindle leads with braided conductive wire, connected at one end only.

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Well last time it stalled, it did it at exactly the same point as the time before. It was just moving over to do another pocket and stalled on its way (so not cutting at the time) and then started milling about 4 inches off its supposed course.

I will check the cable work.

The company told me it might not be getting enough power and needed to be on a direct spur to the main box rather than running off a ring spur.

Although an electrician friend said there was ample power getting to the machine looking at its power consumption/ratings.

If it's faulting at the same spot, with a rapid move, it may be that you've got the maximum speed set higher than your machine can actually run. Try reducing that, and lowering the acceleration while you're at it. Then try the same program again and see if it does the same thing.

The company told me it might not be getting enough power and needed to be on a direct spur to the main box rather than running off a ring spur.
Oh Crap.
They are just trying to dodge the problem.

IF it has stalled at the same point several times, that could mean that there is a tight spot on that axis. Or it could mean that the cable movement is causing a break somehow at the point. You could try halving the peak speed and acceleration (both of them) and re-running the program. If the fault is gone, you could have been stalling the motors. If it has not gone, I would check the moving cables.

Cheers
Roger

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Originally Posted by RCaffin

The company told me it might not be getting enough power and needed to be on a direct spur to the main box rather than running off a ring spur.
Oh Crap.
They are just trying to dodge the problem.

IF it has stalled at the same point several times, that could mean that there is a tight spot on that axis. Or it could mean that the cable movement is causing a break somehow at the point. You could try halving the peak speed and acceleration (both of them) and re-running the program. If the fault is gone, you could have been stalling the motors. If it has not gone, I would check the moving cables.

Cheers
Roger

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Hi Roger. Its a new machine and done little work so far. The company guy is being very helpful, but suggests a filter plug (Copper block?) in case its a power feed problem.

I have changed all speed and acceleration settings, and changed the plug to another source.

It has just cut out a job correctly, ...... but when it finished, rather than park, it went to do the same job again. The V-Carve animation shows it doing it once. Is there a setting in MACH 3 that tells it to repeat? I don't think I changed anything?

'Filter Plug'
That should probably be an 'inline mains filter', and it is actually a very good idea. You can buy a compact metal-cased unit and stick it inside the electronics box straight after the power switch. I use one. Earth it!

Repeat operation
This is not a Mach3 thing; rather it is probably a legitimate g-code thing. Normally I put M30 at the end of my programs: that says 'halt and rewind' (which is not the same thing as the notorious HACF or Halt And Catch Fire). But if your program has M47 at the end, well ... that says M30 and run the program again.
Yes, the animation probably will show the program executing just once - or so it would appear, because the second run will be identical to the first run.

Cheers
Roger

I will have to find an external one as fitting inside the electrics box will void the warranty.

Thanks for info, but it wasn't repeating before when I did previous cuts. Its as if there's a ghost in the machine.

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Originally Posted by RCaffin

'Filter Plug'
That should probably be an 'inline mains filter', and it is actually a very good idea. You can buy a compact metal-cased unit and stick it inside the electronics box straight after the power switch. I use one. Earth it!


Cheers
Roger

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Would this be a good option?

91013005 | Sollatek 250 V 13A PureAC13 Mains Protector | Sollatek

It might do, although I don't know the specs. What I had in mind was more like RS 219-2808. It might be worth while looking inside the box to see whether there is anything like this in place already.

Check the generated program you are running, and see how the program ends. If there is an M47 there, it could have been inserted by the post-processor.

Cheers
Roger

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Originally Posted by RCaffin

It might do, although I don't know the specs. What I had in mind was more like RS 219-2808. It might be worth while looking inside the box to see whether there is anything like this in place already.

Check the generated program you are running, and see how the program ends. If there is an M47 there, it could have been inserted by the post-processor.

Cheers
Roger

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It has the M30 at end.

I have ordered a power filter so will try that next.

Just went to try a simple job in another area and it went off position again, but it carried on, then went back on course.

The milling drill was howling a bit (6mm 2 flute) , but it hasn't done that much work. Maybe 30 mins so far.


I'm beginning to hate this machine.

One other thing is it was supplied with a laptop all set up for MACH 3, it supposedly setup for the system but does have alert messages come up saying no virus protection etc.

It has no connection to wireless or internet.

a simple job in another area and it went off position again, but it carried on, then went back on course.
Now that is wierd.
You see, if it goes off course and loses position, that's probably the hardware - usually noise getting in somewhere.
But if it goes 'off course' and then back ON course, that is SW, and I would strongly suspect the CAD/CAM generated stuff. If it comes back on course then both the machine and Mach3 are likely working fine.

You need some test programs. Something to start at a central 'origin', send the machine around in circles and up and down for a while, then back to the centre origin. If it can come back to the start properly, then the machine & Mach3 are running OK. Can you write one?

Alert messages saying no virus protection may be safely ignored and even turned off IF the machine has no internet connection (wired or wireless, doesn't matter). You should NOT put any virus protection or firewall on the machine: they can screw up Mach3 badly by interrupting it at the wrong time. And of course NO internet connection.

Cheers
Roger

Quote:

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Originally Posted by RCaffin

a simple job in another area and it went off position again, but it carried on, then went back on course.
Now that is wierd.
You see, if it goes off course and loses position, that's probably the hardware - usually noise getting in somewhere.
But if it goes 'off course' and then back ON course, that is SW, and I would strongly suspect the CAD/CAM generated stuff. If it comes back on course then both the machine and Mach3 are likely working fine.

You need some test programs. Something to start at a central 'origin', send the machine around in circles and up and down for a while, then back to the centre origin. If it can come back to the start properly, then the machine & Mach3 are running OK. Can you write one?

Alert messages saying no virus protection may be safely ignored and even turned off IF the machine has no internet connection (wired or wireless, doesn't matter). You should NOT put any virus protection or firewall on the machine: they can screw up Mach3 badly by interrupting it at the wrong time. And of course NO internet connection.

Cheers
Roger

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I spent a good hour watching youtube vids of making laptops safe for cnc use. Turned off everything that could interfere in Win 10.

The power filter coming soon, so will try those. I guess its a process of elimination. God damn it, I just want this damn thing to work. Have become scared to use the thing atm.

Thank you for advice.

Quote:

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Originally Posted by RCaffin

a simple job in another area and it went off position again, but it carried on, then went back on course.
Now that is wierd.
You see, if it goes off course and loses position, that's probably the hardware - usually noise getting in somewhere.
But if it goes 'off course' and then back ON course, that is SW, and I would strongly suspect the CAD/CAM generated stuff. If it comes back on course then both the machine and Mach3 are likely working fine.


Cheers
Roger

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It went off course and I hit emergency stop. I then manually raised the Z Axis, then pressed continue in MACH 3 and it seemed to go back to its proper course.

Have become scared to use the thing atm.
He he he
Cheer up - we have ALL been through that stage. :)

Find a bit of 1/8" PVC welding rod - or something similar. Put about 80 mm of it in a collet and dry run your program - without any material on the deck. If the PVC crashes ... tough. Straighten it up.

Can you write g-code test programs?
Update: see attached zip file for 3 simple test programs. All care, ZERO responsibility!
READ the file before use.
Open ONLY with Notepad, NOT Word or Wordpad.
You can change the parameters at the start if you wish.

Cheers
Roger

Thought i'd update the thread,

I bought a power filter and so far its behaving. Looks like interference was a problem.

Thanks for all your help :)