3D Printed Stepper Motor

Intro: 3D Printed Stepper Motor

I recently came across this instructable of a 3D Printed DC Motor and I figured I could take it a step further; Literally. I designed this stepper motor with eight electromagnets, six neodymium magnets, with a 3d printed rotor and stator housing. This is specifically a permanent magnet stepper motor capable of 15 degree full steps and 7.5 degree half steps. There are many different types of stepper motors but most of them work very similar to the one I have designed here. This is an educational display to show others how stepper motors work. I designed this to run on a 5-12VDC power supply so it will work with most USB power supplies.

I am also doing a giveaway on my Youtube channel. I will be giving away an arduino, transistors used in this project, and some switches. More details in the last step of this instructable.

If you like this project, please vote for me at the top.

STEP 1: What You Will Need

1. Six 1/4" neodymium magnets.

2. 608ZZ Bearing

3. Eight 8d 2-3/8" nails - Not critical what nails you use as long as they fit.

4. Magnet Wire - I used 0.315mm magnet wire but this is not critical.

5. Arduino Uno

6. Four Transistors - I used PNP transistors I had lying around, but you can use whatever transistors you want or MOSFETS as long as you make sure they can handle the current your motor will draw. Read the datasheet carefully for specific recommendations. On 5v mine motor draws about 1 amp and on 12v it demands about 3 amps.

7. 3D Printed Rotor and Stator

8. Glue

9. Electrical Tape

10. A compass

STEP 2: Print the Dodecagon Rotor and Octagon Stator

STEP 3:

Use a compass to determine the poles of your magnets and glue the magnets with the north poles facing outward. If your magnets are strong enough, the compass on some smartphones will show you the polarity of the magnets.

STEP 4:

Press fit the bearing into the stator and then press the rotor into the bearing. I was pleasantly surprised how well the bearing press fit into the stator. When 3d printing, holes tend to want to shrink inward and end up smaller than expected so I usually oversize them a bit.

STEP 5:

Cut 9 pieces of wire to 25 feet and wind them with a drill. Use a compass and a battery to determine the configuration required to give you the south pole at the head of the nail. Use a marker or heat shrink tubing to mark the negative lead of your electromagnets. Wrap the sections of the electromagnets with electrical tape where they will come in contact with the stator housing. This serves two purposes. It firmly secures the electromagnets in place and also insulates the housing from any heat the coil may produce. The coil pairs draw about 1 amp with the 5V power supply I am using. The transistors I chose can handle using a 12V power supply that the coils draw about 3 amps from. The problem with the higher voltage supply is that if I leave it running for a bit, the coils start to get warm.

Warning:

I designed this to run on a 5-12VDC power supply. If you decide to stray off the beaten path, use Ohm's Law to determine what size coils you want. V = I*R

Remember, the fewer windings on your coil, the lower the resistance is going to be. If you are not careful, your coils will pull more current than your power supply or transistors can handle and bad things will happen.

STEP 6:

Push the electromagnets into the stator until they're about 1/4" from the neodymium magnets. You can slide the electromagnets in and out as you wish, but I didn't want them too close because the nails will become magnetized much faster. That's the downside of using the nails. The motor will still work once they become magnetized, but it will be less efficient. Welding rods are a good alternative to the nails if you have some laying around.

STEP 7: Solder Everything Together

Wire up your coil pairs in series and connect them so that all the south poles of the electromagnets face inwards. The resistor I used in the schematic is a 1k resistor. The purpose of this is to prevent the digital pin from "floating" high when in the off position. Again, make sure to use a transistor capable of holding up to the current that your coils will be demanding.

Load the source code to you arduino and you're ready to go!

If you like this project, please vote for me at the top.

STEP 8: Pay It Forward!

I will be giving away an arduino, the transistors used in this project, along with some switches and jumper wires.

Rules for the giveaway:

Subscribe to my YouTube Channel, like this video and leave a comment on the video saying what you would like to see me build next. On September 1st I will randomly select a subscriber's comment and ship them out for free! Thank you guys for being such a welcoming community!

Comments

[themoreyouknow]

I was taught in science class in school that iron stays magnetized and steel does not. iron nails are commonly sold as wire nails and are cheaper than steel nails. steel is much harder to bend. you might have better results with the latter, and be able to locate them closer to the magnets.

[jman 31]

Hey there, I'm an electrical instructor at a Technical college. I love this instructable because it showcases exactly how steppers work. I am almost finished with mine with the LED upgrade and I will be using it as an object lesson for my students. I have one question though.... It seems you have the PNP transistors hooked up in an NPN configuration with the load on the positive side. Maybe I'm confused as to how PNP transistors work, but am I correct there? Obviously it works, so no problems there, but I have NPN transistors and I want to make sure I wire it correctly.

[dicoy]

Is welding rod a better alternative than nails to avoid magnetizing? What would be the best choice for that?

[Proto G]

There's no need in this scenario. Even if the nails eventually become magnetized, the motor will still work. Ferrite rods would be the optimal choice.

[CrisC2]

Great project. Wondering what you would need to increase the torque of this motor? And is there a special Arduino code?

[DylanL4]

You know what the next "step" is.... (sorry could help it)... to make a complete 3d printer using the 3d printed stepper motors...

[tomatoskins]

This is awesome! Thanks for reaching out to me as I've been out of town and would have missed this. Great job!

[Proto G]

Check out my latest instructable. I added LEDs to the motor to help visualize which coils are energized.

[Proto G]

Thank you, I'm glad you like it! I'm making an axial flux stepper motor next. It will actually be strong enough to use in a future project!

[gfalcone1]

Great! Congratulation!

[Proto G]

Thank you!

[bpark1000]

Portescap made stepper motors by using jigs to hold all the parts of the stator in position while molten plastic was injected. This made a lightweight, inexpensive, rugged motor. (Unfortunately, after they cheapened the process, the plastic deformed with age and the motor jammed. Customers then became leery of the process.)

[BrianT5]

Great instructable! I have a basic knowledge of electromagnetism, so my question relates to the winding of the coils around the nails. You use an electric drill (great idea!), I see that the coils have a tendency to cross over one another during winding. How will this affect the strength of the magnetic field, do you think? I have seen this type of winding on cheap commercial motors. If it is worthwhile, I am thinking of setting up my hobby lathe to do the winding so that the windings are sequential with no random cross over. Thanks again for a great idea.

[bpark1000]

Crossing over of the wire in the winding has no affect on the magnetic field outside the internals of the coil (the fields of the crossings cancel) What counts is the number of turns, and the total winding resistance. The only affect would be a "practical" one (if the winding were so sloppy that you couldn't get as much wire in the space). That is not an issue in this motor as there is lots of space available, and the efficiency and the power density is not important in this demonstration motor.

[bluebriant]

Thanks for the reply. If the fields cancel, then this would reduce the magnetic field?

[bpark1000]

No. At least not the one that counts. When you have a wire in a helix carrying current, there are 2 magnetic fields created. One is along the axis of the helix, and powers this motor. The other loops around the cores (like the coil windings) and provides no useful purpose in this motor. Left-hand and right-hand wire helices produce fields that add up along the core, but cancel out the useless looping fields.

[Proto G]

Thank you! I saw no noticeable difference in the coils that I carefully wound with no cross over and ones with cross over in terms of their magnetic performance. It is better, but not noticible at such low power.

[zurkog]

I think it'd be cool (and educational) to stick 8 LED's near the tips of the electromagnets so that you can actually see which pairs are being energized.

[Proto G]

Yeah, my second version will definitely include LEDs.

[CFW]

Nicely done!

I've used it to explane to my students how magnetism can drive a motor and they understood it clearly.

Do continue the good work.