Strange stepper behavior

Hi, I'm getting some strange behavior from my steppers and I don't know why.
They start fine but pretty soon the start to jitter

It's kinda hard to explain so I made a vid of it. Here.

I have a Sanguinololu board using Sprinter, and I'm using Pronterface on my computer.

As for the motors themselves, they are Astrosyn steppers Type 17PM-K502-P1ST (That's all they say on the anyway, I just got a bunch off ebay)

I'm at a loss here, no idea what's causing it. If anyone has any ideas it would be very helpful. Thanks.

If the steppers are not getting enough current they will jitter and not rotate continuously, if using ramps try turning the pot clockwise until they don't miss steps anymore.

If you try to run the steppers at a feedrate that is too high they will only jitter. Have you calibrated steps/mm in your firmware? Have you set feedrates too high?

If you run the steppers hard they will get hot and at temps above 60 deg celcius they start to give me problems with reduced torque and missed steps.

Looks like the current is set too high to me. They run OK for a while until the chips get too hot and start cutting out, cooling a little and cutting back in. That is the pulsing effect you see in the second half of the video.

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[www.hydraraptor.blogspot.com]

Thanks guys, I adjusted the pots on the stepper drivers and they are all working now

I have 8 motors Type 17PM-K502-P1ST, same as yours.

I cant find documentation about it;

Please could you explain the parameters for voltage and current you are using ? Max Volt, Max Amp etc ?

I have a generic TB6560 4 axis controler rated at 12-36V and 1.5-3.5A, and doubt if can use it with the motors.

Thanks in advance,

I am in the process of building my first prusa v2.
I am having a similar problem with two of my pololu drivers.
The z axis is not working, but x, y, e axis work ok.
I tried swapping z stepper motor connectors with y, and y has the same issue, but z works.
I reverted back to the original setup, but now I swapped the pololu drivers of z and y axis.
Now, z works fine but y has the same issue.
It must be an SMT issue on pololu drivers.

Is there any way to check/fix SMT related problems?

im new to repraps.

when you say steps per mm, it is a theoretical calculation based on the knowledge of your equipment or you physically measure? or a mix of both? so say if my Z axis is based on 200 steps/rev and it does 1.5mm on a machined thread, i should program the firmware to read 133.333 steps per mm right?

i have yet to recieve my arduino, but my ramps board is already here. looking at the ramps board with polulu driver

power supply on the left, each board with its mini VR pot on the right side.

the flat detent is about facing 9.30am .... which "current" position is this?

i have also read the ramps wiki, i dont seem to find data on the relative turning position of this VR. the VR seems to be continous turns w/o a end stop.

aplavins Wrote:
-------------------------------------------------------
> If the steppers are not getting enough current
> they will jitter and not rotate continuously, if
> using ramps try turning the pot clockwise until
> they don't miss steps anymore.
>
> If you try to run the steppers at a feedrate that
> is too high they will only jitter. Have you
> calibrated steps/mm in your firmware? Have you set
> feedrates too high?
>
> If you run the steppers hard they will get hot and
> at temps above 60 deg celcius they start to give
> me problems with reduced torque and missed steps.

redreprap Wrote:
-------------------------------------------------------
> when you say steps per mm, it is a theoretical
> calculation based on the knowledge of your
> equipment or you physically measure? or a mix of
> both? so say if my Z axis is based on 200
> steps/rev and it does 1.5mm on a machined thread,
> i should program the firmware to read 133.333
> steps per mm right?

Yes, except that most people run at x8 or x16 microstepping, so multiply that 133.333 by 8 or 16, depending on your driver settings.

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A quick update, the ebay seller "reprapdiscount" shipped two pololu drivers for free. Nice guy.
Replacing the damaged driver resolved the Z axis issue altogether All axes are running smoothly now.