DIY - Self Made STEPPER MOTOR (electromagnetics)

Step 1: Intro to DIY Stepper Motor

Hello all ,the. DIY stepper motor is made of an electromagnetic stator and permanent magnet neodymium rotor.

Sequential and alternate activation of stator using mosfet helps the neodymium magnets placed rotor to rotate to a particular step angle.

This project is carried out for developing a student kit for bringing better understanding about internals and concepts of stepper motor.

Questions:

1. What is solenoid and electromagnets ?
2. How Polarities of electromagnets are formed and reversed?
3. What are permanent magnets ?

Not Much a difference between the both , Solenoid and Electromagnets are coils of conductors that create magnetic field lines around it when electric energy is applied.

Simply Alternate to permanent magnet which has fixed north and south pole, but here with electromagnets the north pole and south pole can be reversed by reversing the direction of the current flow. As an addon the Magnetic field can be switched on/off by switching the current on/off.

The current entering point or positive supply end of the electromagnet is called South pole. The current leaving point or negative supply end of the electromagnet is called North pole.

Does that Make Sense ? A little…….

Step 2: Making and Machining of the Base

The base plate of hylam is routed in the router to create a slot at the center for rotor bearing and other slots for stator holders.

The mosfet clamps are also placed in the base plate

Other stator Holder parts are routed and placed to complete the setup.

Refer: Images above for Hylam machining

Step 3: Stator Coils and Electromagnet Winding

Thus 22 gauge or approximately 0.8mm copper wire is used to make an electromagnet by winding the copper wire around the bolt.Washers and Nuts helps to place the bolt on hylam made stator holders. The bolts are winded with three layers of copper to make electromagnet.

The Electromagnets are placed in hylam stator holders such that the Head of the bolt faces inwards. The ends of coil wire enamel are stripped with an emery abrasive sheet or by heating the enamel with a lighter.

Same way, Eight such bolts are winded and placed in the stator holders such that the head of the bolt faces inwards. Thus each head of the bolt facing inwards constitutes a polarity dependent on positive and negative supply.

The positive end or positive supply (+) voltage where the current enters the coil is the South Pole

The Negative end or Negative supply (-) voltage where the current leaves the coil is the North Pole.

Thus after placing all the bolt heads facing inwards the coils are connected to form pair’s shown below. Therefore 4 pairs of Electromagnets with north and south poles are formed.

Note to Remember:

The positive supply where current enters the coil forms a south pole and Negative supply where the current leaves the coil forms the North pole.

Images
1. The Image depicts wiring loop for creating 4 Electromagnets.

2. The Images above with pair of bolt represents a single Electromagnet where poles facing inwards

Step 4: Rotor Design With Permanent Magnet

The Rotor is made of a wooden piece attached to the base plate through a 608zz bearing, the wooden piece is attached with neodymium magnets with even spacing .

Most importantly the magnets are placed in such a way that the same polarity of the neodymium magnet is facing outwards(ie. either North or South). I have placed the magnets in way all the north pole facing outwards.

The south pole of magnets are glued strongly to the wooden circular rotor piece.

Note:

The Rotor Magnets pole facing is depicted in the above image;

Step 5: Wiring and Working

The Mosfets uses the Negative switching option so that the Negative supply to the electromagnets comes via mosfet.

The ends of coils connected to other poles via wires.

• The Arduino is used to switch the excitation in a sequential manner 1-2-3-4. (Note: Arduino Code, I have just used digital Write on pins 2,3,4,5 one by one without 1 second delay causes the excitation one by one)

The Four Electromagnets with North and South poles facing inwards are alternately excited one by one.

Each excitation causes the permanent magnet to attract the south pole and repel the north pole ( ie. Since in the rotor all the permanent magnet are with north poles facing outward attracts south and repels north)

North- South Attracts

North- North Repels ( like poles repels and unlike poles attracts)

Thus Each excitation will create a particular step angle of rotation.

The sequence of Excitation 1--2--3--4.

Step 6: Conclusion

Make a try with , Excitation of different sequence of electromagnets. Obtain accurate step angle by placing the permanent magnets and electromagnets at distance.
youtube: https://www.youtube.com/watch?v=8i2UTiUnvJo