Figure 6 
View of interior of stepper 
motor drive assembly. The 
stepper motor drives 
through a toothed nylon 
belt, which can be adjusted 
for tension. The 
declutching devices can be 
seen at the outer ends of 
the assembly. 
  
  
128 
Figure 
Thompson-Watts Coordinato- 
graph. General view 
showing stepper motor 
assembly in place. 
  
Figure 7 
Rear view of 'Astrosyn' 
stepper motor.