After a year of testing here is my Closed Loop stepper drive .
Its available Jan 1 2016 at Viper Servo motor products
Money back satisfaction guarantee and 1 year warantee
Manufactured in Canada
for more information, contact
Larry kenny
LarkenTechnology
613 746 5685
Viper Servo motor products or Larken Automation
https://www.youtube.com/watch?v=EYXU...ature=youtu.be