Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video


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Thread: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video

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    Default Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video

    I've got a hybrid CNC Router Parts machine we've been building for a long time and I just CANNOT get it to run smooth. I've written hello world once with it, but even simple movements cause it to shudder, jam and lose steps. I'm using Mach4, PMDX usb board, 54v toroidal power supply feeding KL-9082 bipolar stepper drivers. On my X axis, i'm using a digital driver (DM860T) because one of the 9082's failed so I replaced it with that and it seems to work flawlessly.

    Anyways, it always seems like the dual motor axis is fighting itself when you give it too many movement commands, go too fast, etc. It seems like it skips a step, binds, grinds and jams. I've disengaged both motors from the R&P and the gantry slides easily the entire length of the machine, no binding or anything. When you hook it up, no matter how tight or loose you engage the gear tighteners, it always seems to jam up somehow. See video below for more details.


    Here's screenshots of all my relevant settings. Am I missing something easy????
    Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video-control-config-jpg
    Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video-motor-configs-jpg
    Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video-pmdx-stepper-config-jpg

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video-control-config-jpg   Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video-motor-configs-jpg   Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video-pmdx-stepper-config-jpg  


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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Am I missing any information that might be needed to help figure this out?



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Have you tried at lower speed and acceleration?
    Perhaps your gantry is not squared well enough, or something else binding one or the other motor. Does the gantry move smoothly and easily without the motors? Difficult to guess by just looking at it. I don't have Mach4, so I can't help you with that bit, but 400in/min requires a lot of voltage and current, so perhaps the 54V is not enough, especially since you also have a gearing factor, which means lower torque. I don't know this, but looking at the pulleys it looks like you have smaller pulley on the motor which drives a larger one, but I have no idea about the gear factor. Also, it seems like your whole motor/gear assembly is shaking. Does it supposed to be like that?



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    That gear system is definitely jumping some gears at that speed. Like stated above, I would look at the R&P setup to see if its suppose to be that loose. Also, cut the accelerations down to 200ipm and see if it still jumps gears.



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Quote Originally Posted by firepong View Post
    That gear system is definitely jumping some gears at that speed. Like stated above, I would look at the R&P setup to see if its suppose to be that loose. Also, cut the accelerations down to 200ipm and see if it still jumps gears.
    You mean the speed not the acceleration...



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    The speed is already super slow. The machine should be rated for 1200 inches per minute rapids, and we're nowhere CLOSE to that.
    Gantry is super square. It moves extremely smoothly (one finger to push it back and forth) and sometimes slides several feet after you let off of it. At no load, it should EASILY be able to coast at that speed.



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Add more spring force on Rack and pinion by tightening the bolt... Decrease acceleration and Velocity..and start from Low to High and see at what velocity acceleration combination your Gantry is running flawless then decrease by 10% of both... This is because you are not cutting yet and no cutting forces are applied on the system.. My two cents

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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Quote Originally Posted by skylineworkshop View Post
    The speed is already super slow. The machine should be rated for 1200 inches per minute rapids, and we're nowhere CLOSE to that.
    Gantry is super square. It moves extremely smoothly (one finger to push it back and forth) and sometimes slides several feet after you let off of it. At no load, it should EASILY be able to coast at that speed.
    Claiming all this is pointless. Your gears are shaking heavily, that is NOT normal to my eyes. The speed you have is high already, even if the manufacturer claims 1200in/min, which I think is hard to reach unless everything is optimal. It is obvious that you have a problem, you wanted help and we try to help you out. It is not easy since we are not where you are. What sort of power supply are you using? Many things can be wrong, you have to start somewhere. Starting slow is a good way of locating problems, so you should reduce the speed and acceleration to half. You can always increase it later, but first you have to find out what is wrong. Perhaps it's just a simple thing, perhaps not, perhaps a combination of many things.



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Why does the motor bounce out away from the machine? There is a mechanical issue there somewhere. I would not expect to see lateral movement like that. You want the pinion to remain engaged in the rack.
    Kinda glad I went with a fixed pinion drive which has been flawless

    Rod Webster
    www.vehiclemods.net.au


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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    Dual motor rack and pinion drives are great and very reliable and will last longer than fixed pinion setups if adjusted properly. I haven't read through all of your post and settings so excuse me for guessing. It could be a number of things. If this is a dual motor axis, make sure all the settings match exactly if both motors and gearing is the same. If they are a mismatch, it can be very hard to get things in sync. Even if they are the same, then obviously if the steps per or any motor tuning settings are different you'll have issues. Are the dip switches for the driver micro steps the same. Also the drivers if not the exact same make/model same can cause issues even of the micro steps setting are the same. Try it with one motor removed (or not engaged with the rack) at very slow speed... if it works, try the other. If both work independently, you have a setting or hardware mismatch most likely. The symptoms n your video will also occur if the is slipping of any pinion gear etc. Regardless of what you "think" you should be able to run your axis at, start very slow with low accel and speeds and then work up until an error occurs and troubleshoot it. If it's not one of the issues I mentioned above, friction or resistance mechanically will change max speeds tremendously to the neg.



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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    The motors are stalling due to acceleration being too high is my first guess. There are things that can be addressed as well. Typical stalling will not displace the gearing. I see the timing belt drive moving a significant amount when the stall occurs. That is not normal operation.
    How do you re zero the axes?
    At HOME, do you have two separate home switches? Do they operate independently of each other to square the gantry during each home move?

    Lee


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    Default Re: Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + vide

    First, contact CNCRP and send them the video.

    I agree with Rod, that the drive assembly should not be moving laterally like that. It's probably causing some binding as the pinion gets out of alignment with the rack.

    Gerry

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Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video

Gantry is stalling, shaking, and losing steps. At my wits end. Screenshots + video