Trying to tune Vcore 400mm

I attached the ADXL345 accelerometer to Vcore 400mm and ran the macros in RatOS for belt tension and input shaping. I gather working on belt tension should be done first, but my graph looks nothing like others, so what does it mean? Too tight, not tight enough?
No description
No description
No description
25 Replies
swdee
swdee•11mo ago
I incrementally tightened the belts and retested but it made little difference to the shape of the graphs above. So decided to take the tensioning blocks (from the EVA toolhead) apart and sand them down a bit so they slide easier in the toolhead. Reconnected everything and retensioned the belts and have new graphs as follows.
No description
No description
No description
swdee
swdee•11mo ago
Still not sure if this is any good or not. Secondly I don't understand why the resonances_X graph shows no X or X+Y+Z lines? Looking at other peoples graphs the belt tension from 0 to 25 Hz is always pretty flat, but on mine its high straight away. What does that mean?
technofrikus
technofrikus•11mo ago
I dont have much experience with this either, but what I read is, when the graphs look very different from the goal, usually something mechanical is not correct. Loose screw etc. And did you watch this video from the pins? Explains a lot. https://youtu.be/M-yc_XM8sP4
3D Printers & a Whiteboard
YouTube
How to Read and Analyze Input Shaper Graphs Generated by Klipper
This video is supposed to be a brief overview on what the input shaper graphs can tell us. It is the first video of a series of videos which will give a more in depth view on the kinematic system and input shaping in Klipper. As always: feel free to jump to those parts, that help you with your problems: 00:00 Intro 00:57 What we can learn from...
swdee
swdee•11mo ago
Yes, I have watched that video, but it doesn't provide me with any ideas of what to do.
Steef
Steef•11mo ago
Is the accelerometer attached properly? Screws decently tight? The response is all over the place
swdee
swdee•11mo ago
Yes I have checked the accelerometer is tight and all other screws on the EVA head (and the frame too).
Steef
Steef•11mo ago
I think the tension on your belts is low, do you happen to have an Android phone? If so, install "Spectroid" from the play store Then push your gantry all the way to the back, touching the Y-endstop Then, pluck your belts like a guitar string and measure the frequency with the Spectroid app What size is your printer? Belt frequency should be at least 50 Hz for a 500 size, 60 Hz for a 400 size, 70 Hz for a 300 size
swdee
swdee•11mo ago
The printer is a 400mm. Here is a screenshot of the Spectroid graph, red line represents the plucked belt. Are you able to send me a screenshot of what the spectroid graph should look like as a good example?
No description
Steef
Steef•11mo ago
Hmmmm, unfortunately that seems OK is it the same for both belts? when you run the shaper graphs, do you hear things buzzing or rattling around?
swdee
swdee•11mo ago
Yes, both belts produce the same shaped spectroid graph. I have made a video running the belt tension macro, I do hear buzzing/vibrating but I kind of expect it does that too a certain degree versus rattling of a loose bolt for example. https://youtu.be/csMBvypBn_Q
swdee
swdee•11mo ago
That is the graph produced in the video.
No description
Steef
Steef•11mo ago
I wonder if the cable attached to the accelerometer has too much freedom and it's transferring motion of the cable to the accelerometer. Can you tiewrap the blue cable to the black cable and test again?
Steef
Steef•11mo ago
No description
Steef
Steef•11mo ago
I'll make a video of mine to compare, a moment
Steef
Steef•11mo ago
Steef
Steef•11mo ago
You have things vibrating nearly constantly, I assume you have checked all the screws etc 😄
Prav
Prav•11mo ago
@swdee start by executing ACCELEROMETER_QUERY and MEASURE_AXES_NOISE to verify if the sensor is faulty, your graphs shows basically nothing but signal noise.
oskar7122
oskar7122•11mo ago
Tie that adxl-cable down to make sure that the cable is moving with the toolhead. I have tied mine down into the green cable-gland and (I think) also tied it down on the right side of the toolhead just by the extruder or something *striped it down Not certain that this is it, but it's a theory which could explain it.
swdee
swdee•11mo ago
I cable tied the cables and bowen together but it didn't make any difference to the graph above.
No description
swdee
swdee•11mo ago
I was wondering if the sensor could be bad also so brought another one, hopefully it will arrive in the next few days. Running those commands gives me the following output; accelerometer values (x, y, z): -151594.176922, -3034.844362, 156819.748441 accelerometer values (x, y, z): -151594.176922, -2886.803174, 156819.748441 Axes noise for xy-axis accelerometer: 0.000000 (x), 87.583522 (y), 0.000000 (z) Axes noise for xy-axis accelerometer: 0.000000 (x), 87.162055 (y), 0.000000 (z) Ran them twice for comparison. I am not sure what the ranges should be, I did see online the noise axes should be in rang of 1-100.... hence those zero values maybe an issue? I tried tieing down the cables but it did not make any difference unfortunately.
Prav
Prav•11mo ago
accelerometer values (x, y, z): -151594.176922, -3034.844362, 156819.748441 accelerometer values (x, y, z): -151594.176922, -2886.803174, 156819.748441
it shows that it accelerates almost 2G in X and Z direction, it should be close to 0 on 2 axes and about 1G on on the 3rd one the accelerometer is broken @swdee ^
swdee
swdee•10mo ago
ok, thanks for that... i'll wait for the new one to arrive and re-test New accelerator sensor finally turned up and this one actually works and I am now getting data which looks similar to what it should be doing. Axes noise for xy-axis accelerometer: 20.746252 (x), 18.938507 (y), 47.780332 (z) Axes noise for xy-axis accelerometer: 21.558181 (x), 19.457533 (y), 53.079426 (z) accelerometer values (x, y, z): -296.082377, -9178.553681, 1685.410096 accelerometer values (x, y, z): 0.000000, -9104.533087, 1302.362347
swdee
swdee•10mo ago
New graphs generated by a working accelerometer above, these look more like the examples I see from others. Any comments on them? @Prav @oskar7122 @Steef @Technofrikus
No description
No description
No description
oskar7122
oskar7122•10mo ago
The last one - belt tension is uneven. But i'm not very good at these. Max accel < 5300 for Y with MZV at 42hz, I think you can safely tension belts a bit more. I think @Helge Keck would say that both your vibrations on the last graph / belt tension are a bit "crazy" and that you should try to tighten stuff (screws, make sure cables etc can't shake) to decrease those vibrations > 100hz. Try tightening the upper belt 0.5-1 turns and rerun the belt tension graph. Also run an input_shaper calibration every full turn or something and make sure you don't go too high in MZV hz for y. I can't remember if ~40hz is "tight enough" for Y for a 400mm³ (meaning, you're already a little bit too tight) or if it's closer 45-50hz that's the "max" Y on my 400 is tuned to 44hz mzv and gives max accel at ~5900mm/s², but I have a little bit lighter weight gantry (and probably a heavier fan - sanyo denki 9gax something)
Prav
Prav•10mo ago
in the last graph frequency is the most important thing, not the amplitude. the amplitude difference can be caused by one belt being a bit more streached than the other or unequal length, like a single teeth of difference. good to fix not the end of the world.
Want results from more Discord servers?
Add your server