Installed new motors, not working!

Hi,

I recently bought some new motors for my printer, NEMA17 2AMPs from ebay (Motors Ebay Page - if you want to have a look at the specs) and today got them all attached and plugged in only to find that I can't get them to work properly. The problem is: whenever I try to move any of the motors they do one good move and then start clicking and skipping for any subsequent moves. This keeps happening until the printer is reset. The other thing is that the motor drivers, A4988 Stepper Motor Drivers (Drivers ebay page - again, if you wanna see specs) are getting extremely hot quite quickly...

Have tried: Removing belts in case they were too tight - same problem
Adjusting the potentiometers to many different levels - at lower levels they moved less, at higher levels they moved more but still same clicking and skipping.
Flipping plugs - No change, other than direction

Personally I'm not super savvy with electronics so I don't really know what I'm looking for however I have a sneaking suspicion that it might be an issue with the drivers, although I have seen people using the same drivers for larger motors so...
Using a RAMPS 1.4 on an Arduino Mega 2560.

Happy to answer any other questions or try anything to test it.

Thanks,

Chris.

Hi,

Set the drivers to 0.85v.

++JM

Those little drivers can't handle 2A. If they got "extremely hot very quickly" you may have destroyed them. Look into higher current rated drivers such as this.

Edited 1 time(s). Last edit at 09/20/2015 12:17PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote

Those little drivers can't handle 2A. If they got "extremely hot very quickly" you may have destroyed them. Look into higher current rated drivers such as this.

I agree. A4988 drivers can only handle about 1 amp, with proper cooling somewhere around 1.5 amps can be attained. Try changing your drivers to drv8825. They can handle 2 amps without cooling easily.

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Prusa i3 Rework - Ramps 1.4 - E3d Lite6 - Full Graphic LCD Controller

Hi,

Guys, it's not because the motors are rated 2A
you can't make them work with allegro drivers.
I ran 17HS8401 motors with some A4988,
since two years now and
neither the drivers or the motors get too hot.
The 17HS8401 are rated 1.8A btw.
Just set the drivers on the proper voltage and this will be ok.
For 2A rated motors, just set the output voltage to 0.85v.

++JM

2A rated current is not an ideal choice for the motors. It's more usual to choose motors rated at between 1.2A and 1.7A for repraps, so that A4988 and similar drivers can get closer to the motor rated current before they overheat. However, it's often possible to run the motors at 50 to 60% of their rated current and get adequate performance. So try turning your drivers down to run the motors at 1A or a little higher. If your drivers have the usual 0.1 ohm sense resistors, that corresponds to Vref of 0.8V or a little higher - similar to the 0.85V suggested in the previous reply.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hey guys, thanks for the replies, decided to try the DRV8825s so ordered some from China for a fraction of the cost. They've just arrived and the problem seems to be solved so thanks for the advice!