Random Z axis plunge <com errors>

[mjgraber]

All,

I am new to CNC Router’s. I have built a router based on Joe’s design and have modified a few items in the build. Such as the moutor mount plates and table.

My issue is with the z axis plunging into work piece randomly See pictures). I do not see any pattern when this happens. I did upgrade to CNC12 Router and ran the CNC PC tuner, delated a few apps that I will not ever use (mostly Microsoft apps), checked to make sure fire wall was off and wi-fi was in airplane mode. I did go thru and set the steps and paired the axis.

I am using Huangyang 2.2 kw spindle, Stepper on-Line closed loop Nema 24 motors, Cl57T Drivers using Switching Power Supply 350W 48V 7.3A. I also have installed Avid pro rack and pinion. Linear Guide Rail 2 X HGR 20-2000mm Linear on x and y axis. The z axis has a ball screw. Used CNC VFD Cable 30ft 16/4 Double Shielded For Spindle .8Kw 1.5Kw 2.2Kw 4Kw 4.5Kw and 4.7m(185") AWG20 Motor and Encoder Extension Cable Kit for Nema 23 and 24 Closed Loop Stepper Motors

Everything seems to be running good on the axis drives and I do not hear or see any movement issues. I have run the program a few times and have watched specifically the Z axis, but I cannot identify any issues, except when the z axis drops because of the sound of the bit getting louder. I can move the the x and y axis manually with ease.

I’m not sure what else I can supply, but I have attached a few pictures of the model and the report. I would appreciate any help you all could provide!

I will add more pics in another post.

Thank you in advance,
Mike

[mjgraber]

More pics.

Let me know if more are needed.

Thank you,
Mike

[ShawnM]

There are several issues here Mike.....

-First, your PC does not meet the minimum requirements to run CNC12, Your single thread rating is 1414 and you need a MINIMUM of 1500 per Centroid.
-Second, your turns ratio is WAY outside the sweet spot for a router. You need some gear reduction.
-Third, your steps/rev for the Z axis is wrong. You have it set to 25,800 and that's an impossible number. Set it to 4000 like the X and Y axis. Then make sure the DIP switch settings are correct on the stepper drive to match the 4000 set in the wizard.

You have your lash comp for the X axis set to .026, if this is correct you have a mechanical issue somewhere that needs to be addressed. There's no way CNC12 can make up for that much backlash.

Your error log is filled with communication errors and it's A LOT !!!! Honestly, it's a wonder the machine even runs. Please have a look at this tech bulletin as you have to solve the communication errors before anything will work reliably.

https://www.centroidcnc.com/dealersuppo ... ds/270.pdf

Also read this topic: viewtopic.php?f=61&t=1451

[Sword]

Agree with Shawn. Seeing that you are running a 3D file, your PC is likely starving the Acorn for data. With 3D relief files, the data flow needs to be flowing fast to keep up. I see a few drive faults as well, which might be a result of the data lag and recovering briefly, causing the motors to "jump". Just a thought there. Never-the-less, get a faster PC (higher single thread rating) and also look into the reason for comm errors.

[ShawnM]

Agree with Shawn. Seeing that you are running a 3D file, your PC is likely starving the Acorn for data. With 3D relief files, the data flow needs to be flowing fast to keep up. I see a few drive faults as well, which might be a result of the data lag and recovering briefly, causing the motors to "jump". Just a thought there. Never-the-less, get a faster PC (higher single thread rating) and also look into the reason for comm errors.

Adding to what Scott said, if you have smoothing turned on for these files, which would almost be required, the PC is certainly starving the Acorn for data. But the communication errors are certainly adding to your problem. Those need to be solved FIRST after you get a new PC.

[cnckeith]

follow the details in this post to solve the communication issue First.
viewtopic.php?t=1451

(4) 03-24-2025 13:42:43 946 PC resending # 7845
(4) 03-24-2025 13:42:53 944 MPU requested resend # 680
(4) 03-24-2025 13:42:53 946 PC resending # 7847
(4) 03-24-2025 13:42:55 944 MPU requested resend # 681
(4) 03-24-2025 13:42:55 946 PC resending # 7849
(4) 03-24-2025 13:43:10 944 MPU requested resend # 682
(4) 03-24-2025 13:43:10 946 PC resending # 7851
(4) 03-24-2025 13:43:13 944 MPU requested resend # 683
(4) 03-24-2025 13:43:13 946 PC resending # 7853
(4) 03-24-2025 13:43:23 944 MPU requested resend # 684
(4) 03-24-2025 13:43:23 946 PC resending # 7855
(4) 03-24-2025 13:43:29 944 MPU requested resend # 685
(4) 03-24-2025 13:43:29 946 PC resending # 7857

[cnckeith]

and where is the Acorn mounted?

[ShawnM]

and where is the Acorn mounted?

I was thinking the same thing Keith as I don't see it in any of his pics. Is he using the Acorn shielded ethernet cable? It should not be routed through a bulkhead connector as I see a lot of them on the cabinet. The PC is his biggest issue right now as it's just not powerful enough and choking off the Acorn.

Order of business:
1- new pc that meets the minimum requirements, see this page: https://www.centroidcnc.com/cnc_pc_perf ... ments.html
2- fix the communication errors, see this topic: viewtopic.php?t=1451

[tblough]

It looks like the drives are mounted in front of the Acorn. You can just see the output relay boards peeking through just above the drives.

[mjgraber]

Thank you for all the response, I really appreciate it!

Here’s what I did today:

1. Ordered a new computer Lenovo ThinkCentre M700 Tiny Business Desktop PC, Intel Quad Core i5-6500T up to 3.1GHz, 16G DDR4, 512G SSD, WiFi, Bluetooth 4.0, Windows 10 that was recommended by centroid.

2. Read TB 270

3. Read TB 309

4. looked thru various suggested topics

5. Ran stress test (passed)

6. Found and removed RJ45 adaptor at computer

7. Removed bulk head RJ45

8. connected cable directly from computer to acorn

9. Re-ran stress test (passed)

10. Made sure windows notifications were turned off

11. Set notifications to “Never Notify”

12. Unchecked “allow computer to turn device off….

13. Reran program to see if a difference was made. Did have an z axis drop. Did notice that all z axis drops are occurring during finishing pass. I did have smoothing on.

Having some experience in the machining world, I wanted to make small moves to see if any improvement was made. I have been in situations were a bunch of things were changed in a machine and we got the wanted result, but really didn’t know what caused the improvement.

Shawn, once I get the coms fixed, then I will address the tuning of the z axis. Thanks again for your help and input.

Sword, thank you for the insight, computer ordered…I looked at the CPU’s benchmark, but could not find the model. I hoping that Centroid knows that this computer will meet the benchmark.

cnckeith, I really don’t know how to read the errors you posted {(4) 03-24-2025 13:42:43 946 PC resending # 7845
(4) 03-24-2025 13:42:53 944 MPU requested resend # 680} or where to find them. I would like to be able to read these and other error codes. I have posted a picture of the acorn location in the cabinet ( I ran out of room so, it ended up behind the drivers). Thank you and appreciate your contributions to the CNC community.

tblough, you are correct on the acorn location.

Tomorrow is my volunteer day for the underprivileged, so it will be Saturday before I do anything with and to the router. Hopefully the computer comes in early Saturday and I can concentrate on that and other items that you all have suggested. Thanks for helping me out, I would be very lost without it! I will do my best to post as soon as I can regarding fixes and issues.

Thank you,
Mike