# Two steps forward, one step back per second?

Discussion in 'The Projects Forum' started by Obfuscator, Jul 17, 2016.

1. ### Obfuscator Thread Starter New Member

Dec 9, 2010
2
0
I need to make a 200 step/360 degree stepper motor do two increments of 6 degrees forward, one increment of 6 degrees back every second and have the sequence continue to cover 60 seconds in 1 second increments (one revolution of 360 degrees) so that each increment is 6 degrees or as close as possible for a clock which expresses two steps forward, one step back and keeps virtually perfect time. In the answer to a post a few years ago, the sequence for 3 seconds covered by a 200 step/revolution stepper which stepped exactly 18 degrees in 3 seconds is:

second 1 = 3 x 1.8 degrees = 5.4 degrees
second 2 =3 x 1.8 degrees = 5.4 degrees
second 3 = 4 x 18 degrees = 7.2 degrees
Total degrees/3 seconds = 18 degrees

This sequence is repeated 20 x 18 degrees/3 seconds = 360 degrees/60 seconds

I have figured that my stepper should do:

second 1 = 7.2 + 5.4 - 5.4 = 7.2 degrees
second 2 = 5.4 + 5.4 - 5.4 = 5.4 degrees
second 3 = 5.4 + 7.2 - 7.2 = 5.4 degrees
Total degrees/3 seconds = 18 degrees.

This sequence is repeated 20 times for 60 seconds.

Is that correct to achieve two steps forward, one step back?

2. ### crutschow Expert

Mar 14, 2008
16,180
4,322
That is a weird sequence you have, but it should do what you want.

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3. ### DNA Robotics Member

Jun 13, 2014
199
61
I seem to remember that some stepper motors in old printers were 180 steps per revolution. Maybe Epson? That would make things easier.

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4. ### Obfuscator Thread Starter New Member

Dec 9, 2010
2
0
That would be very helpful. I have a source of old multifunction printers but I need to know the model number.