CNC router occasionally makes jarring noise and home jumps when it does this. Help!!

[JAZZCNC]

Calm down Mr mannering don't go scraping things just yet.!! . . . Still some other things it could be and if you have separate drives there's half a chance it's just a setting or pulse issue.!

Looking at your motor tuning with 320 steps Per setting and presuming a 5mm pitch screw means the drives must or should be set to 1600 micro steps.
This is relatively high for these machines so It could just be your system can't handle that many pulses and your getting missed steps.?

So first we need to confirm this so can you give us a good quality picture of the drives and there wires and Dip switches if any.
Try and find out ther PSU voltage.
Next what is the Kernal speed set at.? You'll find it in ports & pins.

Show us more before spending any money.

[itsmillertime]

Lol Cheers Jazz ;-)

Just got frustrated with trying to get it running consistently! I have just gone out and taken the case off and had a look inside.

It looks like the switches are set for 1600microsteps. From the PSU I can see on the label (DC output 24v and current 12.5A) outside case says drive voltage 24v DC drive current 3A.

The kernel speed is set at the lowest setting 25khz? I have attached some pics of the controller.

[Jonathan]

The kernel speed is set at the lowest setting 25khz? I have attached some pics of the controller.

320 step/mm * 2000 mm/min = 640,000 step/min
640,000/60=10.67kHz
10.67kHz is less than 25kHz ... so that shouldn't be a problem.

[itsmillertime]

Thanks Jonathon for showing the workings of that, makes it a load easier to understand the reasons behind the settings. cheers andy

[JAZZCNC]

320 step/mm * 2000 mm/min = 640,000 step/min
640,000/60=10.67kHz
10.67kHz is less than 25kHz ... so that shouldn't be a problem.

Jonathan I was more concerned that the Kernal speed was set too high which can cause strange happenings like this.!!. . . Long shot but it happens.

Andy.

First are you 100% sure there's no mechanical issues.? No binding etc. It won't take much stickage at these speeds with such low powered motors/drives to rob torque.

If not then next try cutting the same part but in air without spindle running. This will eliminate VFD/Spindle interference.

After that then carefully inspect wires at the motor connectors and at the BOB/drives for any lose connections.

The drives are better than some of these machines but still cheap low quality drives. That said they should do this job thou with just 24v you can't expect too much.

Again I'm clutching straws here but you could try setting the micro stepping to 400 on drives and see if it changes anything. Just do the problem Axis first to see if it alters any thing.
You'll need to go into Motor tuning and set the Steps Per to 80 and retune the motors. You'll see can get much higher velocity on that axis now but I wouldn't anyhigher than you have it now.

Failing any of this working and machine being mechanicly sound then scrap it all and get this MX3660 - 3-Axis DSP Based Digital Stepper Drive Max 60 VDC / 6.0A along with 48V PSU.
It will transform the machine and I'm pretty sure it will fit neatly into your existing box with only slight modification. It comes complete with Digital drives, built in BOB and Spindle speed control.
Rated upto 60V 6A and will easily run motors at 50-55Vdc with a unregulated PSU so if you want to upgrade motors to say 3nm at a later date then you can. . . . .Or take it with you to another bigger machine.!!

[george uk]

Hi

My friend had a similar problem a few years ago, after a lot of messing about, we found a few important but simple things helped out.

1. Check your parallel cable, and both connections, ( someone on here already mentioned it ),
2. Try not to cross any of the cables for the axis, especially with the spindle cable and keep them away from estop cables. but try rout them away from each other, or at least insulate them a bit.

The version of Mach your using, did it come with the machine

3. Some of the Chinese suppliers send out hacked versions of mach ( can not remember the build number ), and its full of bugs,

2 years ago, when dealing with a problem on my friends machine, the hacked version of mach was buggy on the axis drives and spindle speed setup for slow spindle rates.

edit. just looked at your wireing again, you have 3 axis power cables running very close to your other wires, If your Y axis driver is the one on the right side, i would route them power cables elsware, or at least dont let them get close.

[itsmillertime]

Cheers Jazz,

You have been pretty thorough with your suggestions and I do appreciate you taking time out to give your advice. I will go over the machine tomorrow. take off the suspect axis stepper motor and move the gantry by hand to see if it is binding / any resistance present.

As for possible interference from the spindle? I did think of this before. So I've ran g code with the spindle powered off/and in the air and its still stalled. Its very random when it happens.. but it happens frequently enough to prevent me working on anything expensive or intricate. Possibly happens once on every other job. But its enough to ruin whatever I'm doing!

I will physically swap over the x and y driver boards and see if the fault does indeed transpose to the x axis as I suspect. I can barely live with the one problem. But with the Z axis losing its zero. Its a step too far!! boom tish ;-)

Going to also swap out my parallel desktop cable for another one I have and change/ ensure my desktop is in standard PC mode not acpi..

Then I will try the changing steps as you suggest and if that doesn't work after inspecting all cables etc?

I will replace/upgrade all stepper cables and shield the vfd cables. Earthing all of the screens.

Still not working? I will be delighted in swapping out the controller with the one you suggest.

Having these issues are a great way to get to know my way about the machine so I view it as a learning exercise in getting to understand how it all works.

Will let you know how it goes tomorrow. wish me luck!

thanks again for all the help

andy

[george uk]

looking again at your pictures, i would definably suggested routing the wires away from each other, especially the power cables away from the data cables. I would also check that anything supposed to be earthed to the case, is firm

I think mach3 comes in a trial version from there site, ( limited to 500 lines i think ) If your only running at 25kh, the hacked version might not affect you that much, in fact, it was only the spindle controll that we found buggy. Because of all the other things you have tried, its probably interference with the wires, or the driver board ( cheap to replace ) .

Mach3/4 well worth buying a licence for, the support and help you get on there is like the help you get on here, saves you hours of reading and headscratching

[JAZZCNC]

looking again at your pictures, i would definably suggested routing the wires away from each other, especially the power cables away from the data cables. I would also check that anything supposed to be earthed to the case, is firm

It won't hurt doing this but I would be very surprised if this is anything to do with it has he's only running 24vdc. Only the 240V mains voltage will be worth routing signal wires away from has 24Vdc won't produce much noise.
When it's noise it's often a very slow process of missed steps or the complete opposite and it's tripping drives or E-stops etc. If the VFD isn't affecting it then wires being a little close to each other won't be.!

The Parallel Cable is always worth swapping out for another when having trouble and it will probably been me who you've seen suggest before George has i've seen it many times. Thou I don't think it's that in this case other wise would have siggested it.

Andy george is correct about the Hacked version of Mach3 and now knowing this I wouldn't do anything else untill you have un-installed it and replaced with the genuine and currant lock down version.

To be honest I'm still thinking it's a Mechanical issue with binding that's robbing the low amount of torque that's left at the higher feed rates. These motors are 4 wire motors so can run out of torque very quickly when rpm rises and with only 24V then there won't be very much torque to start with.!

[itsmillertime]

Ok guys,

I spent a few hours this afternoon stripping down bits and taking the bed off and removing the stepper motors from the router trying to look for any mechanical binding etc along the Y - the gantry driving axis.

It doesn't sound particularly smooth but I dont have much to compare it to. The gantry moves quite freely by turning the leadscrew by hand. I can freely push the gantry across the length of the machine and back with a gentle concerted push by hand. It's definitely less resistive in the middle section and approx the last 4" at either end the resistance increases by about an extra 15% and the noise from the ballscrew is slightly more pronounced and it's just a little more 'jerky' towards the last 4-6 inches of travel.

I checked the travel and the resistance of the x axis and this is noticeably smoother to push but I think thats because it's lighter and better supported on the 2 bars and less to travel. It does make a similar noise to the Y axis it's just less 'clanky' and smoother.

I moved the gantry right up to the ends and looked for gaps/ being square with the frame. At one end of travel (near the stepper motor) it's pretty much bang on. But at the other end of of the router I measured the gap at approx 2mm in one corner with the other corner at 0mm flush with the gantry. 2mm is quite a noticeable gap across the end. I have attached a photo.

So what's the best way to work out if its true? Could this be causing some resistance? I guess measure across rails at one end and do the same at the other? I haven't removed the lead screw or anything yet as I didn't want to really disturb anything else until I asked here!!

Is there any easy way of doing this, maybe loosen up the rails and run the gantry from the one end to the other? Then tighten up the rails? I checked all the allen screws and all are tight.

I may have found a possible cause of the motor stalling. One of the grub screws on the Y axis coupler didnt feel very tight (possibly loose) and maybe causing the coupler to slip when the load got too much? Not 100% certain that is it. But it's the very same axis that has had the problems.

I guess what I'm asking is, is the noise my machine makes when moved by hand (pushed) normal? Should I expect any resistance at extremes of travel. And whats the best way of making sure its square/ true and not a bent ballscrew.

Where should I go from here please guys?

While I have the bed up and I'm looking for biding/mechanical issues I want to rule them out I guess. Also should there be any oil of grease on the ballscrew? No nipple or any obvious lube in place.



Sorry that the video is 3 mins long but it shows the freedom of movement and sound of my y and x axis being moved by hand.

Below is a photo of the gantry with the gap approx 0mm/ flush at one side and 2mm at the other. I took measurements to show the difference in the gap.



Thanks again for all your advice. Just hoping to rule out any big mechanical issues before going for drivers etc..!

andy