Installing a new Sterpperdriver

[ji11 3]

Hi Ultimakers,

I bougth a new set of stepperdrivers and was wondering how to install them in an appropriate way.

While the how-to about the stepperdrivers [ http://wiki.ultimaker.com/Electronics_build_guide ] goes into detail on setting up the current depending on the motors temperature, it only tells little about the real deal.

The only thing i could find, is that 1.5 A are more than enough. They dont tell you how to set it, before connecting the stepper...

Since i do not want to harm the motor i would like to know how to measure the current.

And in the event of breaking something (+ being curious ) i was wondering where to get a replacement extruder-stepper.

Regards

ji11

 

[owen 19]

Hi ji11

you won't blow your stepper motor if it goes wrong you'll blow the driver board

You can look up the spec sheet for the driver and it shows a pin that you can measure a voltage from that is proportional to the current. It's quite hard to get to though.

Easier to follow the wiki and adjust in very small increments going by sound. The stepper motor growls when too high and misses steps when it's too low.

Important not to turn it up too high. The driver board will blow very quickly, believe me I know :-|.

 

[zuma 0]

Dear Owen,

I have been looking, as have others according to my searches, for the spec sheet that you mention above for the UltiStepper Drivers; in order to find this pin that you measure voltage from and haven't had any luck.

Any suggestions on where to look? The Ulti wiki page only has a CAD drawing and no info.

Also, when you say the "driver board" will blow, are you referring to the UltiStepper Driver itself (I think it is A4988 Carrier board) ? So basically you will kill the UltiStepper, not the main electronics board that the UltiStepper plugs into?

Thanks for the help.

Z.

 

[owen 19]

Dear Owen,

I have been looking, as have others according to my searches, for the spec sheet that you mention above for the UltiStepper Drivers; in order to find this pin that you measure voltage from and haven't had any luck.

Any suggestions on where to look? The Ulti wiki page only has a CAD drawing and no info.

 

Hi Zuma

See this page http://www.pololu.com/catalog/product/1182

Down the bottom it talks about the ref voltage to set for the current and in the picture of the bottom of the pcb it has a white circle around the test pad

 

Also, when you say the "driver board" will blow, are you referring to the UltiStepper Driver itself (I think it is A4988 Carrier board) ? So basically you will kill the UltiStepper, not the main electronics board that the UltiStepper plugs into

Z.

 

Yep, that is correct you kill the A4988 Carrier board, not the main board.

 

[zuma 0]

Dear Owen,

Thanks so much for getting back to me. There was a guy offering a bottle of liquor to the person that found them this information. If I come across his post again, I'll refer him to you ;-)

Thanks again.

Z.

 

[gr5 2,196]

Apparently there are several manufacturers of the A4988 stepper driver. Only one of them is pololu.

There's some more details here on locations to measure vref (scroll down to pololu section):

http://apatureresearch.wordpress.com/2013/03/15/3d-printer-part-2-the-brains-and-the-brawn/

You can see the vref test point just above the trim pot and almost under the heat sink on 3 of these 4 pics here:

http://www.flickr.com/photos/ultimaker/8210300863/sizes/k/in/photostream/

 

[gr5 2,196]

Oh - and it looks like the test point is for *bottom* side access. For top side access you can just measure the voltage at one of the trimpot pins or according to the above website, the metalic part of the potentiometer that rotates can be used to measure vref.