stepper motor gone wild

Texas Carom Club

Texas Carom Club

AzB Silver Member
Silver Member
I lost my z axis`s coupler so I bought another and now when I jog in z up or down it will stutter up and down
some times a lot down when I go up, sometimes a bit up
and vice versa
I didn't change anything but the coupler and it even looks like the same kind on my y axis
ive tried having the set screw on and off the flat of the motor shaft
ive tried having it really tight and ive tried it at only snug on the set screw and nothing changes

I didn't manage a fix through asking on cnc zone so wanted to ask here cause I know theres atleast a few of you using stepper motors

my machine is the 3020 cnc
Chinese from ebay
 
Last edited:
I know nothing of CNC though I am mechanically inclined.
Only a couple of things come to mind but they may be of help.
Are there internal thrust washers/brgs in the stepper mtr?
IOWs, is the shaft moving in/out of the the mtr?
Could there be an alignment issue?
Has anything else changed?

HTHs, KJ
 
No its tightened
shafts not moving in and out
im leaning more toward an alignment issue but Im the opposite of you
I know cnc and am in no way mechanically inclined for this venture
 
If you know how many steps you motor has check your stepper settings in your software.
 
http://www.carving-cnc.com/media/ca...0/9df78eab33525d08d6e5fb8d27136e95/0/2/02.jpg

Looking at the machine, if this is it, you would have a thrust brg at the end of the ball-screw,
opposite end from the mtr.
Has that been loosened; it may require pre-load.
How did you get the orig. coupler out. My guess is that you had to disassemble to get at it.
If so, your reassembly may not be perfect. I suspect something is binding.
If MC2 reads this thread he may jump in with a suggestion or two.
Be patient, he's a busy guy. Good Luck.

KJ
 
You probably have one of a few of problems.

First, I would check to make sure your coupler isn't slipping. I know you've just put it in, but I've seen much crazier things. The way I would check is to turn on the control so the stepper is locked and try to rotate the lead screw. Get a good grip on it and see if it turns before the motors breaks it's hold.

If that is tight, then I'd check to see if you may have partially dislodged a connector, or maybe damaged a wire during the install of the coupler. Based on your description, you may be losing one of the phases of the motor intermittently.

Last but not least is alignment. Make sure you don't have any binding. You should be able to rotate the screw by hand, when the control is turned off so the motor isn't holding. You'll be turning the motor as well, so there is some resistance, but it shouldn't be too much. If you're not sure whether the resistance you feel is too much, then remove the motor or the coupler and rotate the screw then. It should be smooth and pretty easy to move the axis with just your fingers. This will give you a good baseline for what it should feel like with the motor attached.


OH, one more thing. Make sure the motor isn't loose. If a stepper can twist around, it will not perform very well and will miss position a bunch.


I hope that helps!

Royce
 
KJ Cues said:
http://www.carving-cnc.com/media/ca...0/9df78eab33525d08d6e5fb8d27136e95/0/2/02.jpg

Looking at the machine, if this is it, you would have a thrust brg at the end of the ball-screw,
opposite end from the mtr.
Has that been loosened; it may require pre-load.
How did you get the orig. coupler out. My guess is that you had to disassemble to get at it.
If so, your reassembly may not be perfect. I suspect something is binding.
If MC2 reads this thread he may jump in with a suggestion or two.
Be patient, he's a busy guy. Good Luck.

KJ
Click to expand...

Ya thats it
I dont know what a thrust brg is
dont know if it loose
Or what a preload is

yes I took it off by hand unscrewing it from tue motor
thinking if it had an extra set screw it may increase rigidity
th en it got lost and then ordered another online
and now im here
Im thinking its my reassembly but I dont have the knowledge to diagnose it myself
 
RBC said:
You probably have one of a few of problems.

First, I would check to make sure your coupler isn't slipping. I know you've just put it in, but I've seen much crazier things. The way I would check is to turn on the control so the stepper is locked and try to rotate the lead screw. Get a good grip on it and see if it turns before the motors breaks it's hold.

If that is tight, then I'd check to see if you may have partially dislodged a connector, or maybe damaged a wire during the install of the coupler. Based on your description, you may be losing one of the phases of the motor intermittently.

Last but not least is alignment. Make sure you don't have any binding. You should be able to rotate the screw by hand, when the control is turned off so the motor isn't holding. You'll be turning the motor as well, so there is some resistance, but it shouldn't be too much. If you're not sure whether the resistance you feel is too much, then remove the motor or the coupler and rotate the screw then. It should be smooth and pretty easy to move the axis with just your fingers. This will give you a good baseline for what it should feel like with the motor attached.


OH, one more thing. Make sure the motor isn't loose. If a stepper can twist around, it will not perform very well and will miss position a bunch.


I hope that helps!

Royce
Click to expand...


Far as I can tell its not slippinh and the motor isn't loose
 
Loose wire or connection between motor and controller gets my vote - only becasue I've seen it before and your symptoms match.

TW
 
Pure insanity or who knows
while fiddling around with the set screw on it today a co worker comes by asking whats that
and I demo it for him getting to the problem of the z and its working now
I don't have any idea of how or why but what ever slight adjustment I made earlier has for now atleast I can jog up n down in z normally
now will it be okay while cutting
who knows im only gonna cut wax and wood with it from now on anyways
 
Not too long ago when I was setting up the Z on my new rig, I had much the same symptoms. I checked for alignment and all the suggestions above. Then I was back in Motor Setup in Mach3 and noticed that somehow my acceleration and speed on Z had "moved" to 0.:eek: I set it back to 10 or so and VOILA! no stuttering, grumbling, etc. on Z.
Just another data point.
Gary
 
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