Symptoms of Belts too tight

New Home Forum Mostly Printed CNC – MPCNC Troubleshooting – MPCNC Symptoms of Belts too tight

This topic contains 49 replies, has 8 voices, and was last updated by Profile photo of P3DCNC P3DCNC 3 months ago.

Viewing 30 posts - 1 through 30 (of 50 total)
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  • #26821
    Profile photo of Jason
    Jason
    Participant

    What would the symptoms of your belts being to tight? This shaking issue is getting annoying. LOL

    #27455
    Profile photo of Jason
    Jason
    Participant

    Shaky Axis

    If you watch closely you can see the x/y axis vibrating as it moves. It moves smoothly when moving faster like when homing.

    I have tightened and loosened the belts no change. Played with acceleration and jerk no real change.

    It also does it just travelling in X or just travelling in Y. Now I used cheap ass chinese bearings could I have a bad bearing or 2 in the X/Y Center section?

    The rails look rough but are actually really smooth.

    #27456
    Profile photo of P3DCNC
    P3DCNC
    Participant

    I have the same issue. I don’t think it’s my belts and they are quite tight. I actually think it’s a combination of 1. dust on the rails and bearings and 2. xyz gantry is not square.

    Number 2. above is my key issue I think because in order to square it, I do like others have said and run the x and y against physical stops to square it, which my x/y needs to move one of the braces a 1/2 ” to do so. Also, when milling I noticed that the motors locations are smooth, it is the xyz assembly that jitters. One other thing is that cutting diagonals leaves ribs in precisely the same places. So the errors are repetive and reproducible. So it may be something else perhaps a gcode issue as well.

    #27462
    Profile photo of Jason
    Jason
    Participant

    I know my is square as well. I use an end stop on one side and a block on the other. 99 out of 100 times it finishes square too.

    Yes exactly the motor rollers move smooth although you can feel the vibrations in the belt. I guess just vibrations transferring throughout the machine.

    I guess a test would be replacing all the bearings in the X/Y center section. I do not do much router cutting to see repetitive inconsistencies.

    But on mine the shaking is predictable when it is running diagonal on raster laser engraves.

    What are your rails made from @P3DCNC?

    #27463
    Profile photo of P3DCNC
    P3DCNC
    Participant

    25.4mm stainless. 25″x49″ working area.

    #27464
    Profile photo of Jason
    Jason
    Participant

    Same rails… I am running 48×48 working area.

    #27465
    Profile photo of P3DCNC
    P3DCNC
    Participant

    Nice. I’ll troubleshoot mine tonight a bit. BTW, circles are also an issue.

    #27466
    Profile photo of Jason
    Jason
    Participant

    They are jagged i assume? Mine are round just not smooth.

    #27467
    Profile photo of P3DCNC
    P3DCNC
    Participant

    Same. Interestingly, I’m cutting 3mm deep with an 1/8″ bit through a 3/4 piece of plywood at 1000mm/min, and the patterns repeat through all the layers perfectly.

    #27469

    The video seems to be unavailable. Can you post it again?

    #27470
    Profile photo of Jason
    Jason
    Participant

    I did a wood sign that had a 1/3 circle feature from 1.5″ cedar and same result the pattern was repeatable thru the entire cut. was cutting 1mm deep with a 1/4″ bit.

    Are your bearings of the cheap chinese variety as well? There was a point that my machine would make loud grinding noises but those seemed to have stopped recently. Not sure if that was the chromed finish getting chewed of the rails or a ball in the bearing getting chewed up… It seemed that the timing of the grinding was repeatable on the rail.

    #27471
    Profile photo of Jason
    Jason
    Participant

    I do not have any issues accessing the video with the link.

    #27476
    Profile photo of P3DCNC
    P3DCNC
    Participant

    No grinding. Part of my planning tonight is to remove the belts and see if the movement is binding anywhere.

    #27478
    Profile photo of Jason
    Jason
    Participant

    i did that the other day… Mine moved very smooth. All my tensions bolts are so loose they are almost falling off. I did find tightening them made it worse.

    #27480
    Profile photo of Jason
    Jason
    Participant

    What do you have your driver voltage set at? I think if I remember correctly I have mine a 0.7

    #27483
    Profile photo of P3DCNC
    P3DCNC
    Participant

    If it’s not mechanical, which I will be checking tonight, then my next guess is firmware.

    Could it be that we are running settings that are too coarse? I must admit this will be an area I haven’t touched in a while. But I am using RC7 pretty much stock other than the usual changes.

    Another thought I had was to compare milling a circle near a corner of the bed and one in the middle of the bed and see if there is an improvement in the corner milling where it’s stiffer.

    #27484
    Profile photo of P3DCNC
    P3DCNC
    Participant

    I haven’t touched the voltages. They are stock from Vicious1 but are now wired in Series.

    #27485
    Profile photo of Jason
    Jason
    Participant

    90% of all my laser work takes place is the first 400mm of my axis. I have only had one job go beyond 600mm in either direction.

    I have tried 1/32 stepping. I am currently at 1/8 stepping. Problem still exists.
    Problem existed in parallel and series.
    I have been meaning to move back to RC8 but have not got that far. I was running it for a bit and at that time no change.

    #27510
    Profile photo of RAGII
    RAGII
    Participant

    I have the same issue and have narrowed it down to the center assembly. I took my center assembly off and did some running and everything was nice a smooth. As soon as I install the center assembly (I am using the old design as I purchased my parts from here last May) I see the shaking. I have tried to loosen up the bearings in the center assembly but it does not seem to make a big difference.

    #27513
    Profile photo of Jason
    Jason
    Participant

    I wonder if we loosen off the bearings in the center assembly that are not related to tension on the bars… I know i have mine locked down tight. If they had a little wiggle room perhaps would absorb the vibration so to speak. I have had this issue across 2 versions of this machine as well. Old and new parts, conduit and smooth stainless.

    @vicious1 do you have any ideas. Definitely seems to be something in the center assembly.

    #27526
    Profile photo of Brian
    Brian
    Participant

    The video link does not work for me either.

    #27533
    Profile photo of P3DCNC
    P3DCNC
    Participant

    So I had a look at my machine.

    The rails and bearings were dirty. I had to use an sos pad to get the buildup off of it.. Doesn’t look like more than a black line down the contact area of the bearing but it sure smoothed out the X and Y movements.

    Loosened a bunch of the bolts that tighten the bearings to the rails everywhere. Not much noticeable difference in moving with your hands (disconnect from RAMPS first).

    It seems to only be movements that have a component of X and Y in their moves. Moving just in the X is smooth. Moving just in the Y is smooth. Anything else, a circle, diagonal, etc, all have a pulsing that you can feel and see…sounds like firmware. Not gcode, cause I’m using the manual controls to move things around at different speeds.

    Ideas ?

    #27534
    Profile photo of P3DCNC
    P3DCNC
    Participant

    @jason your video is set to private. Only you can see it…

    #27536
    Profile photo of P3DCNC
    P3DCNC
    Participant

    I slowed the speed down to F50. You can hear it alternating between x and y steppers as it moves at a 45 degree angle. My 3D printer doesn’t do this. Hmm.

    On my 3D printer, a diagonal line is very smooth. Circles may have some facets, but each facet is smooth.

    This does seem like a firmware setting to me.

    #27540
    Profile photo of Zeenon
    Zeenon
    Participant

    Following….I see the same thing:

    XY movement

    #27544
    Profile photo of Ryan
    Ryan
    Keymaster

    This is with stuff purchased from me or no?

    #27548
    Profile photo of Zeenon
    Zeenon
    Participant

    For me yes, all stock (no firmware updates). Estlcam 10 and Repetier.

    Z

    #27552
    Profile photo of P3DCNC
    P3DCNC
    Participant

    @vicious1 yes this is the kit purchased from you. I am using Repetier and Fusion360 but all the tests I’ve made since discovering this is with manual control in Repetier. I did notice that the video from Estlcam on how to setup the xbox controller talks about feed rate, acceleration, and inertia (jerk basically) and how to set the upper limits. I’ve not done this on this machine. As noted though, my 3d printer uses the same hardware (RAMPS and Mega) and it does not do this.

    @vicious1, is there a documented procedure on how to tune these settings?

    It really looks like this is the culprit. What do people have these set to?

    #27554
    Profile photo of P3DCNC
    P3DCNC
    Participant

    Interesting, although my 3d printer prints well, I do get some jerk issues. I realized this when I recognized the same effect in my prints as shown in this post http://3dprinterwiki.info/wiki/wanhao-duplicator-i3/duplicator-i3-calibration/firmware-settings/. I will experiment with acceleration and jerk on both my 3d printer and mpcnc. I think this may be part of the problem. Although it doesn’t explain the alternating of x and y motors during diagonal moves…

    #27556
    Profile photo of Ryan
    Ryan
    Keymaster

    The machine is pre-tuned, if you are using my hardware, That is why I ask if you are using my stuff or not. There a tons and tons of videos of people drawing with the mpcnc, This is not a common issue.

    Me and you poking around in the dark is not getting us anywhere and I don’t have enough information to help. The questions in the sticky post really make helping easier but start with these.

    1-Your machines are both double the recommended size in foot print but neither of you specificity the most important one of height. and what material are you using stainless or conduit.

    2-Picture of your machine So I can spot an obvious errors. A picture is literally worth thousands of words in this case.

    3-That jagged drawing I need to see how it was set up, what tool mount, what pen, what surface were you drawing on, how big is the actual drawing?

    4-Screenshots of all the speeds you were using in whatever software.

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