Computer Controlled Dobby Parts List (Stepper Motor Version)

General Comment on design:
This design uses common parts from the "Maker" community, it's a dynamic marketplace in both availability & cost.
This is a concept which could be applied easily to Do-It-Yourself design but wouldn't lend itself too well to a production environment
since things tend to change quickly & without notice.   

Item			Quantity		for			From
Mechanical Parts:
 Stepper Motors 	1 for each shaft	Moving Shafts		See Note 1  (42BYGH404 from Circuit  Specialists)
 5/16" Shaft Couplings 	1 for each shaft	Connect rod to motor	Amazon
 1/4" Shaft Collar 	2 for each shaft	Hold thread to rod	Marshalls Hardware (over rod size to hold connecting thread)
 5/16" Rods		1 for each shaft	Support shafts		Home Depot
 Side walls		2 (Left & Right)	Structure/Motor Mount	See Note 2
 Top			1			Structure		3/4" x 6" x 26" (depends on loom)
 Cord			about 2' per shaft	Connecting Shaft to Rod

Electrical Parts:
 Arduino Mega 2560	1			Smarts			Amazon (Elegoo, See Note 3)
 Prototyping Shield	1			packaging		Amazon (pack of 10 mating with the Mega 2560 pinout)
 ULN2003A Driver	5			Motor Control		Mouser (See Note 4
 12V power supply	1			Electrical Power	Amazon
 Foot Switch		1			"Advance button"	See Note 5
 

Notes:
1. Motors are key in function & cost - The 42BYGH404 I used I selected in spring of 2019, it has about 3 in-lbs of torque, I bought 10 for about $6 per.   It is a NEMA 17 motor which defines the mounting pattern for a 1.7 inch motor, any size could be used - all it affects is the height of the 
  Dobby Assembly  I'd recently noticed a NEMA 23 motor with more torque for a lower price.
  These are 6 wire motors allowing a center tap on each coil to simplify the electronic drive - if you want to use 4 wire motors you will need to
  reverse the polarity of the coil and the electrical circuit is a bit different, using a L293D to control each motor is an option (at higher cost)

2. Side walls - I used laser-cut acrylic with a touch of petroleum jelly to lubricate the ends of the shafts.  

3. "Arduino Mega2560" essentially a generic term for an interchangeable board, the units I bought from Amazon were built by Elegoo

4. The ULN2003A is a 7 channel Darlington driver.  Each motor requires 4 drivers, one motor for each shaft (8) needs 32 driver channels @ 7 drivers
   per package gives 5 drivers, for 4 loom shafts 3 ULN2003A, for 12 shafts 7 ULN2003A.    I used the prototyping shield board plus pin headers to mount the drivers, soldering 

5. Foot Switch - I used a doorbell button mounted in a piece of wood, overlaid with another piece of wood to buffer pressure from your foot to the    button & keep it clean.  I used 1/4" phono jacks to allow the foot switch to seperate.  Could also be any foot button & connectors.
   Press button raises shafts, release lowers shafts & advances the user interface software to next weft shot