Linear actuator / Stepper Pusher / 28BYJ-48 / M5 rod

Edit to add V2:

• frame V2 with standoffs, through holes to screw it down to a plate. Frame narrowed in the front to have two stand closer together
• M5 top to screw on to the front, not to scratch and pushed buttons and to have option to adjust length. M5 thread needs to be cut manually after print

• example picture of two unit, small PCB with an Arduino nano, two A4988 driven by a 18650 and step up module to 9V I previously made a lever for a 9g servo pushing buttons - which becomes too weak quite easy.
  https://www.thingiverse.com/thing:2806324

  This setup uses a 28BYJ-48 12 V Motor, converted to bipolar and a A4988 stepper driver.
  Such a cheap stepper is capable of about 5Ncm of what I've read.
  ... With the M5 setup to convert rotation to linear, this results in roughly 25N pushing force, along with 10mm travel.
  It is not fast, but gets the job done;-)

  You will need besides the motor and the electronics 3 nuts M5 and about 50...60mm threaded rod M5.
  The motor is held in place by two screws M3x8, threaded directly into the plastic.

  One M5 nut is pushed into the coupler which is then pushed onto the motor shaft.
  I aligned the other two M5 nuts on the threaded rod and fixed then with a drop of super glue.
  These nuts then slide inside the frame.
  Thus one rotation of the motor pushes the rod along with the two fixed nuts 0.8mm according to thread pitch forward.

  Both parts print upright without support and like 8mm bridging requirements.
  Printed mine in PETG.

  Print Settings

Printer Brand:

Anet

Printer:

A8

0.2

Infill:

20%