Trying to troubleshoot some jerky motion in cuts

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muibubbles
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Trying to troubleshoot some jerky motion in cuts

Post by muibubbles »

I've been having some chatter/jerky motion within my diagonal cuts and arcs. I just upgrades to v5.06 so now I'm rechecking all my settings/configuration. As I was re-doing my turns per rev I noticed the dial indicator needle kind of bounces/hesitates every 0.01" move vs a smooth sweeping. This is ran with the feedrate of 5IPM. I might be reaching, but I think this could be the cause of the edge quality in my cuts. I have this issue with the x and y axis. Any ideas what could cause this? Noise? Resonance? Issue with the driver or stepper motors?



Specs:
Axyz 5014 retrofitted with centroid acorn
Vexta pk299 f4.5a stepper motors
KL8060 drivers
3:1 gear reduction (iirc)
Rack and pinion
Micro stepping set at 3200 and at 1600 with the same results (changed the settings in cnc12 and the dip switches on the driver)

In the picture you can see the curved portion is much choppier than the straight cut (it was a diagonal). Cuts along the axis has the same "line frequency" but more consistent and you cannot feel any ripples.
material 6061 aluminum
one was cut with a 3/8" onsrud o flute cutter, the other with a YG-1 ALU Power 3/8" 3 Flute
both were cut with multiple depth cuts, with stock to leave set at .015 for the final pass
work holding is a vacuum chuck with a custom jig that was specifically gasketed for this part
I've also tried this with and without smoothing in cnc12 and fusion 360

I really don't think the issue is in the cut or feeds/speeds, I think it's the machine or some settings/parameters I missed but I'm lost what to diagnose next.
Attachments
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report_689E19871027-0918192459_2023-08-30_21-41-09.zip
(1.06 MiB) Downloaded 10 times
Last edited by muibubbles on Thu Aug 31, 2023 1:16 pm, edited 1 time in total.
Nigelo
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Re: Trying to troubleshoot some jerky motion in cuts

Post by Nigelo »

Some general observations:

- X and Y axes are set to slow jog faster than Fast jog which is the reverse of what you would normally set
- X and Z axes are set to 3200 counts per rev but Y set to 1600. Is this what you intended for testing or an oversight? Either way, the Drives must always match Acorn's settings on each axis as you correctly say.

Having said that, all photos show extremely jerky cuts in all dirctions and definitely my first course of action would be a full "service" on all mechanical components. Mechanical motion must be completely smooth and you may need to disconnect your steppers to feel this by hand.

You can then go on to review test cuts in each axis. I also use YG-1 Alu Power but nowhere near 5 ipm you stated. My YG chart for 10mm 3F cutter with 45deg helix (E5E51 & E5D72 series), shows an optimum 8000rpm at 3,470 mm/min feed (136ipm). This produces approx 50 ipm at the 3,000rpm max spindle speed shown in your report. As I usually machine without coolant I would reduce the feed to around 25ipm for testing at 3000rpm but generally use the fastest rpm available with feed to match in proportion.
Hope this helps
Nigel

"You can lead a horse to water but you cannot force it to drink"
muibubbles
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Re: Trying to troubleshoot some jerky motion in cuts

Post by muibubbles »

Hey Nigelo, thanks for your response.

-I'll double check the jog rate, while upgrading to v5.06 and having to manually input all the settings again I may have goofed it.

- the axes are set to different step counts because I wanted to rule that out as the problem. I was doing testing last night when I changed it and I generated the report after I threw in the towel😓

-Can you provide more advice on servicing the mechanics? I just re-greased all my bearings. When I disengage the steppers y axis slides pretty easy. X axis is a little harder (it feels more like weight than something binding) my Y axis rack and pinion definitely show more signs of wear when jogging but the x axis is silent but I'm getting the jerky motion is both axises. This leads me to believe it's stepper/driver related? The stepper motor is very hot to touch- I wouldn't be able to hold it for more than 2-3 seconds. Is this an indication of something wrong or do they generally run hot?

Sorry for the confusion- 5 IPM was the feed rate in the video doing the turns per rev Calibration. My cuts in the aluminum have been anywhere from 12000rpm-18000rpm and 40IPM-72IPM. My spindle/VFD is not connected so it will always read 3000rpm... I will probably revive that thread shortly 😂
Nigelo
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Re: Trying to troubleshoot some jerky motion in cuts

Post by Nigelo »

Unfortunately, I have no experience of your aXYZ machine but consult your OEM manual for servicing if available. Generally you need to carefully clean all ways, leadscrews, racks and sliding surfaces etc before applying lubricants and only where recommended, most importantly with the correct grade of oil or grease. You are really looking for anything that can cause excess sticking and not just binding as well as nothing loose / out of proper alignment - so check all screws, bolts and fasteners.

The hot steppers may be a clue but again, I have no experience of Oriental Motor products - I use Japanese Sanyo Denki units on my Mill and Lathe and they all get warm rather than hot. Too hot to touch for longer than 2-3 secs suggests around 60c which seems excessive especially at idle but may be normal for your units. I assume the Drive dip switches for current are correctly set and your Power Supply does not have excessive voltage.

Hope this helps but perhaps someone else could chime in with more direct experience of your equipment.
Hope this helps
Nigel

"You can lead a horse to water but you cannot force it to drink"
Ken Rychlik
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Re: Trying to troubleshoot some jerky motion in cuts

Post by Ken Rychlik »

1-Check the actual voltage supply to the drives if you are reusing the oem power supply. They might have several taps to match different incoming voltage.
2-It the artwork thousands of tiny lines, or a smooth arc? Look at it in node view of the software if you can.
3-You might try the opposite direction of cutting. If the scrap part that this came from looks smoother, reversing will help.

My first hunch is that curve has a thousand nodes, considering the diagonal cut is better.
Ken
muibubbles
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Re: Trying to troubleshoot some jerky motion in cuts

Post by muibubbles »

Nigelo wrote: Thu Aug 31, 2023 11:09 am Unfortunately, I have no experience of your aXYZ machine but consult your OEM manual for servicing if available. Generally you need to carefully clean all ways, leadscrews, racks and sliding surfaces etc before applying lubricants and only where recommended, most importantly with the correct grade of oil or grease. You are really looking for anything that can cause excess sticking and not just binding as well as nothing loose / out of proper alignment - so check all screws, bolts and fasteners.

The hot steppers may be a clue but again, I have no experience of Oriental Motor products - I use Japanese Sanyo Denki units on my Mill and Lathe and they all get warm rather than hot. Too hot to touch for longer than 2-3 secs suggests around 60c which seems excessive especially at idle but may be normal for your units. I assume the Drive dip switches for current are correctly set and your Power Supply does not have excessive voltage.

Hope this helps but perhaps someone else could chime in with more direct experience of your equipment.
The manual states specific grease points/ spots to clean- all which I've already done so I can cross that one off.
I'm waiting for delivery of my dial test indicator today so I can start verifying some of the mechanics. I "think" my rack and pinion is worn but I cant find any definitive info on how to really determine that. Also my table is huge, 6'x14' so its a lot to replace. I don't mind spending the money if it will fix it, but financially, I can't buy new replacement parts with the hopes they will eventually fix the issue.

I'll try running the machine today and get some temperature readings. All I have to base my knowledge on is from my old CNCRouterparts 2'x4' machine and I dont recall the motors getting this hot nor this loud. (albeit these motors are 3-4x the size)
EDIT- just double checked and I think the voltage may be running too high! *see next post*

the dip switches on the drivers have been verified and are set up correctly. They are set to the max 6amps however the steppers require 6.3amps is the difference an issue or negligible? The power supply voltage has been checked and within range.

I appreciate your feedback either way, thank you!
Last edited by muibubbles on Thu Aug 31, 2023 1:58 pm, edited 1 time in total.
cnckeith
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Re: Trying to troubleshoot some jerky motion in cuts

Post by cnckeith »

make a photo album of the machine and electrical cabinet so we can see what you are working with.
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
muibubbles
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Re: Trying to troubleshoot some jerky motion in cuts

Post by muibubbles »

Ken Rychlik wrote: Thu Aug 31, 2023 1:08 pm 1-Check the actual voltage supply to the drives if you are reusing the oem power supply. They might have several taps to match different incoming voltage.
2-It the artwork thousands of tiny lines, or a smooth arc? Look at it in node view of the software if you can.
3-You might try the opposite direction of cutting. If the scrap part that this came from looks smoother, reversing will help.

My first hunch is that curve has a thousand nodes, considering the diagonal cut is better.
1- Just went to triple check and looks like I was incorrect. (Disclaimer- I am not good with electronics so its best to assume I don't know what I'm talking about) The voltage from the transformer (machine is 220 3phase) to the Power board (bottom left label 50vdc) is reading 35vdc. Each wire, grey and blue reads 35vdc when I probe one terminal at a time to ground (if this is the correct way)

Now at the top- where the wires go from the power board to the stepper drivers reads 40-70vdc. But, when I test them with a multimeter is it reading 83vdc. Sounds like this could be the culprit? I have no idea how this powerboard works but i assume its suppose to take 50vdc in and output 40-70vdc? But its taking in less voltage and putting out more than it should?

2- I'm aware of the tiny line segments and tons of nodes, I'm not sure how to check in fusion360 but it was sketched using lines and arcs so It shouldn't be an issue. Also I just edited the first post since i forgot to add the video- if you look at the dial indicator you can see jerky motion while im trying to calibrate it. After re-watching a bunch of marty's videos, the dial indicator needle always moves fluidly. This is why I also believe the issue lies somewhere in the stepper motor/drivers

3- the scrap part looks equal or worse. For reference the part was climb cut.

Thanks for your feedback, I think the voltage may be the culprit.
Attachments
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371498965_1094751658165800_7686470006102219810_n.jpg
muibubbles
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Re: Trying to troubleshoot some jerky motion in cuts

Post by muibubbles »

cnckeith wrote: Thu Aug 31, 2023 1:56 pm make a photo album of the machine and electrical cabinet so we can see what you are working with.
Let me know if there is anything specific you want to see!
Attachments
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muibubbles
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Re: Trying to troubleshoot some jerky motion in cuts

Post by muibubbles »

More info:
The driver Terminal reads the following voltage:

(24-80vdc) VCC+ 82-83VDC
GND- 0VDC
A+ 41VDC
A- 41VDC
B+ 41VDC
B- 41VDC
Attachments
372102944_6895890150461269_2270631827126719452_n.jpg
Last edited by muibubbles on Thu Aug 31, 2023 4:55 pm, edited 1 time in total.
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