New Lowrider CNC making strange noise and struggling to move

LowRider CNC Troubleshooting
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Hi, I finished building my Lowrider V3 recently, and have come to a halt in the test stage as the Y axis of my Lowrider doesn’t seem to be working well. I originally thought the Lowrider was not rigid enough but that doesn’t appear to be the root of the problem and I’m struggling to see the problem so I thought I’d ask for some help here. I had a similar problem with the x-axis before but managed to fix that and I don’t think the problems are related. Below are two videos of me trying to run the y-axis motors, both of which are running now. I have been trying to test them at what I believe to be pretty low feed rates of 600mm/min but in the longer video I also show how the problem gets worse at a higher feed rate of 1200 but although this is relatively fast I’m quite sure it shouldn’t be having any problems since there is no actual load. I may be missing something so any help is appreciated, if you would like any pictures I’m happy to provide them.

600mm/min video

600mm/min followed by 1200mm/min at 00:27

Also I am using the skr pro board with control through WiFi using the esp-01 and software provided here:

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Saw your post because if the reference to the wifi link.

My first guess is a timing issue with the stepper drive. The firmware has to have the correct timing for the type of driver boards you are using in your controller. Tmc2209 vs A4988 etc. If the firmware is configured wrong then the drivers will be driven incorrectly which will
Cause crap drive signals to the motors. As I recall there are timings for acceleration as it starts up and during run mode. If either is wrong you could see this behaviour. And worse is wrong timing may cause lost steps under load which will be a nightmare when carving.

Of course the other possibility is a poor connection to a motor that causes poor drive current during vibration which is worst at startup where current loads are high and vibration on startup is worse.

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Am also curious what steppers and drivers are on the machine? Stepper bottom looks different to my V1E steppers.

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Is your controller enclosure ventilated to help avoid Stepper drivers overheating?

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Asked ChatGPT out of curiosity, some of the suggestions are not bad and worth considering…

https://chat.openai.com/share/61d53940-c58d-4c1e-8b1c-24f9987c3b3b

Shared ~1min clip showing crude Y motion tilt test to help rule out mechanical cause(s).

Your black Y rail/pipe looks nice.

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Also think bad connection of the stepper connector at the board.
I believe it’s the skr board like mine with the printed enclosure. On placing the cover of the enclosure i had trouble not pulling out or losen the connections.
I wiggled of the black plastic covers on the board itself like suggested in the manual, that helped a lot.
Did you tried that?

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@tjones99 . Ok so I opened the marlin file I had initially uploaded and saw that it had some tmc driver defined in configuration.h so I changed that to A4988 (this is what I’m using) for each of the axis and re-uploaded the firmware to the board. I don’t think much has changed though (at least from what I could check through the Wi-Fi software–I’ve attached a screenshot of these settings, but I’m not sure if this is what you were referring to or not), and now even the x-axis is struggling to move again. I don’t know if this is a hint that the problem is firmware, but its slightly strange that both parts seem to move ok when I apply a little force myself in the direction of movement.

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image1120×1147 63.9 KB

Came back after writing the above, thank you because your suggestion helped find the root of at least part of the problem and long term is helpful anyways, but I looked into tuning the current on the drivers after this and i seem to have found the root of problem! Presumably they were set too low or something as i have adjusted them all to allow the correct current. Or at least as close as i could get it with a vref of 0.8 volts, this was the maximum I could get although the equations online suggested it should be 1.4, to be honest i don’t full understand it, but my motors seem to have a relatively high current rating of 2A.

Now while all my motors are now running a lot more smoothly and y seems to run ok at 600mm/min at 1200 sometimes one side seems to get stuck/not move? It’s not rlly making as much as a ground sound and mostly just moving so that it’s wildly un square because one side moves while the other is stuck, but the side getting stuck alternates randomly. Its happening to each side separately and randomly so I don’t think its a loose wire issue and with a little force in the right direction behind it it runs smoothly so i think it might be mechanical but again i’m surprised its happening to both sides because i dont see that the non bar side could have anything to catch on? I will try an attach a video tomorrow showing the issue if I haven’t got it solved by then

Shared ~1min clip showing crude Y motion tilt test to help rule out mechanical cause(s).

I tried my best at this test after I sorted the electronic side out, and it seems stiffer/less smooth than yours did. I don’t know if this might be contributing to the problem or not, but any recommendations on how to improve it would be appreciated.
Here is the video:

In response to your question @azab2c I bought the motors through the amazon link provided on the v1 engineering instructions, but this is the link to the specific model that i could find:

You also reminded me that I should probably improve the ventilation for the circuits, as currently its not great, I was slightly worried though about debris from cutting getting in and messing up the electronics though, is there any suggestion you might be able to provide regarding this.

Your black Y rail/pipe looks nice.

Ha. Thx. Was struggling to find a good pipe for the project as there isn’t rlly hardware stores where I live, but chanced upon a perfectly sized curtain rail in ikea one day and it works quite well.

@Steven_Willems

Also think bad connection of the stepper connector at the board.

In regards to this and Terry’s previous mention of this, I will still check the wiring anyways as I noticed I had some dodgy wiring causing one motor to not work great previously.

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Yes I was talking about the settings in configuration.h in Marlin and whenever I modify the Marlin file I also make a very slight change to my initial menu screen so that I am sure I am running the version that I think…

I was not referring to the GCODE settings that you listed, but those can also affect things for sure as they set things like acceleration and max speeds… looking at mine I see the same settings so none of those look out of ordinary.

echo:; Steps per unit:
echo: M92 X100.0000 Y100.0000 Z400.0000
echo:; Max feedrates (units/s):
echo: M203 X50.0000 Y50.0000 Z15.0000
echo:; Max Acceleration (units/s2):
echo: M201 X180.0000 Y180.0000 Z80.0000
echo:; Acceleration (units/s2) (P R T):
echo: M204 P180.0000 R3000.0000 T180.0000
echo:; Advanced (B<min_segment_time_us> S<min_feedrate> T<min_travel_feedrate> J<junc_dev>):
echo: M205 B20000.0000 S0.0000 T0.0000 J0.0400

I will add that I had motion issues on my MPCNC that took me a LONG time to track down… losing steps… and eventually I tracked it to cheap bearings I had bought… They were binding and causing lost steps due to high drive force. I literally replaced 80 bearings I think, all smooth since then (well smooth until a wire broke and spindle went one way only and drove itself into my workpiece up to the collet… That’s when I eliminated every unnecessary connection I had… mine was one bad crimp)

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Oh, just remembered one other thing I wanted to mention as you said setting A4988 current… I assume you are talking about the trim pot on the A4988 boards and setting the voltage with a multimeter attached to the screwdriver turning the trim pot??? So the current is based on that measured voltage over a resistor on the A4988 driver board… What I discovered is that not all A4988 use the same value resistor.

See this article

and

Some boards have .1 ohm and some have .05 ohm some have .068 ohms so the voltage depends on what your boards have. Calculate that based on your board sense resistor value.

I have to admit, I switched to an SKR board with TMC drivers and never looked back…

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When adjusting the current: Too high and the steppers and drivers warm up. Our rule of thumb is keeping the motors under 50C so the PLA doesn’t have a chance to get soft and deform. Too low and you will get skipped steps. The biggest advantage to the TMC drivers is that the current is set by the skr and you don’t have to use the trim pots. With the a4498 drivers, I believe the drivers getting too hot will disable that axis until they cool down, which should be more than a few seconds. That is pretty obvious.

Wood chips and dust don’t damage the electronics. But if you want to fo the extra mile, you can put a filter material in front of the fan.

Check the grub screws holding the pulley to the motor shaft. Those should be secured with blue locktite.

You can manually move the machine and make sure the smoothness is consistent and low resistance. If you have bad bearings or a snag, that will be obvious. Make sure no vac hoses or wires are getting caught.