Hi Tom,
have received my motor brackets today and immediatly started testing. Adjusted the current by trial and error which was no big deal and everything runs smoothly and silent after a couple of minutes. But then, hell broke loose
I use two identical NEMA17 motors. SY42STH47-1206B --> Link to datasheet, page 16:
http://www.kosmodrom.com.ua/pdf/SongyangPdf.pdfI've tried to adjust the current by measuring Vref. I set both 8825 to 0,41V. My motor specs are 4V and 1,2A so I thought I'm safe but while one motor (RA) is purring like a kitten at goto speed 512, the other one (DEC) becomes hot es hell... to hot to touch in fact. The DEC motor is also rumbling and chattering and is very loud. DRV8825 chips become hot as well at 0,41V
If I lower Vref to eg 0,20V the motor becomes louder but temp is going down as well as torque. If I raise Vref higher than approx 0,30V the motor becomes to hot.
Wiring: According to my datasheet yellow and white are the "middle wires" so red+blue and blk+grn are the pairs. I have soldered one pair to the middle pins and the other pair to the outer pins. Think thats fine.
Step Angle: Reseller datasheet said 0.9 so I asked uncle google and found the (hopefully) original datasheet which told me 1.8 degree
I have changed this with the confi utility but it's all the same.
Summary:
RA runs on 0,21V on speed 512 very silent without getting too hot (you can touch it) --> OK
DEC becomes too hot no matter what I do. If I'm below 0,21 torque is too low for moving the scope and if I raise Vref the motor and the DRV8825 becomes way too hot.
Any idea what I've messed up? Why does the DEC motor becomes so hot though Vref is so low?
Cheers
Martin