Changes

In this arrangement friction on the thread due to weight of the load is the principle constrain on the choice of motor torque. A conservative approach to this choice would be to allow up to 5 lb of weight per support point, dry-sliding coefficient of friction between pieces of aluminum of 1.4, about 1/8" lever arm of the torque shaft. Torque capability an order of magnitude above that required to overcome the situation of these parameters (14 oz⋅in)  

In this arrangement friction on the thread due to weight of the load is the principle constrain on the choice of motor torque. A conservative approach to this choice would be to allow up to 5 lb of weight per support point, dry-sliding coefficient of friction between pieces of aluminum of 1.4, about 1/8" lever arm of the torque shaft. Torque capability an order of magnitude above that required to overcome the situation of these parameters (14 oz⋅in)  

[[Image:LinEng_4118-01_StepMotor.jpg|Lin Engineering 4118L-01 Stepping Motor (1.9" variety)]]

[[Image:LinEng_4118-01_StepMotor.jpg|frame|Lin Engineering 4118L-01 Stepping Motor (1.9" variety)]]

The 83 oz⋅in Lin Engineering 4118L-01 (1.9") Step Motor has been chosen. The unit is close in price to the lower torque models and does not exceed the 2 A limit of the inexpensive [[:media:StepMotorDriver_R208-manual.pdf driver]] (meant for lower-end motors).  

The 83 oz⋅in Lin Engineering 4118L-01 (1.9") Step Motor has been chosen. The unit is close in price to the lower torque models and does not exceed the 2 A limit of the inexpensive [[:media:StepMotorDriver_R208-manual.pdf|driver]] (meant for lower-end motors).  

The combination of these devices have been found easy to control: the driver has simple direction and step resolution selection pins and uses TTL pulses as step commands. The shaft of the motor, which comes smooth (as in the adjacent picture) when bought from distributors. However, it tested to be more than soft enough to machine a flat into it. A cylindrical "sleeve" with threaded outer surface may be inserted over it and tightened against the flat a small headless screw.

The combination of these devices have been found easy to control: the driver has simple direction and step resolution selection pins and uses TTL pulses as step commands. The shaft of the motor, which comes smooth (as in the adjacent picture) when bought from distributors. However, it tested to be more than soft enough to machine a flat into it. A cylindrical "sleeve" with threaded outer surface may be inserted over it and tightened against the flat a small headless screw.

== See Also ==

== See Also ==

* [[:media:StepMotorDriver_R208-manual.pdf R208 Step Motor Driver]]

* [[:media:StepMotorDriver_R208-manual.pdf|R208 Step Motor Driver]]