There are many ways to make a motor. Here is some info to help understand the various differences in motors and motor parts. I have also attempted to explain the workings of a motor in a brief and concise manner. I have tried to provide simple to advanced info, so don’t get discouraged if you don’t understand something. Some of the pictures have larger versions if clicked.
Words you’ll encounter:
· Can- the main housing of the motor
· Endbell- The end “cap” on a motor can. Holds the brushes and supports the back end of the arm.
· Armature (aka arm)- The spinning rotor inside the can
· Rotor- The “arms” on the armature. This is what the coils are wrapped on.
· Laminations- The flat “plates” that make up the rotor on an armature. Many of them are stacked together to create the rotors.
· Electromagnet ( aka electro-mags)- When electricity passes through a coil of wire, it creates a magnetic field. This is called an electromagnet
· Coil- the wraps (coils) of wire on the armature that make electromagnets
· Winds (aka Turns or Wraps- sometimes shortened to “T”)- How many wraps/turns/winds on each arm of the motor
· Permanent Magnet- The magnets in the can
· Brushes- The part that puts electricity to the commutator and coils
· Commutator (aka Comm)- The comm. Is connected to the arm and the coils. It conducts electricity to the coils.
· Wire Gauge (aka AWG (American Wire Gauge))- A measurement of wire diameter. The smaller the number, the larger the diameter.
· RPM- Rotations per minute. A measurement of spinning speed.
· Can- the main housing of the motor
· Endbell- The end “cap” on a motor can. Holds the brushes and supports the back end of the arm.
· Armature (aka arm)- The spinning rotor inside the can
· Rotor- The “arms” on the armature. This is what the coils are wrapped on.
· Laminations- The flat “plates” that make up the rotor on an armature. Many of them are stacked together to create the rotors.
· Electromagnet ( aka electro-mags)- When electricity passes through a coil of wire, it creates a magnetic field. This is called an electromagnet
· Coil- the wraps (coils) of wire on the armature that make electromagnets
· Winds (aka Turns or Wraps- sometimes shortened to “T”)- How many wraps/turns/winds on each arm of the motor
· Permanent Magnet- The magnets in the can
· Brushes- The part that puts electricity to the commutator and coils
· Commutator (aka Comm)- The comm. Is connected to the arm and the coils. It conducts electricity to the coils.
· Wire Gauge (aka AWG (American Wire Gauge))- A measurement of wire diameter. The smaller the number, the larger the diameter.
· RPM- Rotations per minute. A measurement of spinning speed.
1. Background info
As you know, magnets can attract or repel each other. An electric motor has 3 coils (electromagnets) and 2 permanent magnets. By turning on the correct electro-mags at the correct time, they attract/repel the permanent mags in the can and spin the rotor. This timing is done via the comm and brushes. There are 2 brushes (positive and negative) that sit opposite each other on the comm (which has 3 pick up areas). As the motor turns, 2 of the pick up areas on the comm make contact with the brushes at any given time, and electricity flows through the coil those pick ups lead to. This happens very rapidly.
As you know, magnets can attract or repel each other. An electric motor has 3 coils (electromagnets) and 2 permanent magnets. By turning on the correct electro-mags at the correct time, they attract/repel the permanent mags in the can and spin the rotor. This timing is done via the comm and brushes. There are 2 brushes (positive and negative) that sit opposite each other on the comm (which has 3 pick up areas). As the motor turns, 2 of the pick up areas on the comm make contact with the brushes at any given time, and electricity flows through the coil those pick ups lead to. This happens very rapidly.
Anytime an inductor (in this case the coil) passes through an electric field, it creates a voltage. This is how generators work. This is still true when the motor spins under it’s own power. But, this voltage is going the opposite direction of the voltage we are putting into the motor to make it spin, so it subtracts. This is called back voltage or back EMF. At a certain speed, the back voltage equals the voltage we put into the motor, and (in a perfect world), when the motor is maxed out in RPM, and no electricity flows, thus no current. However, there is friction etc, so the resulting current at full RPM is the amount necessary to overcome this resistance. Thus the lower the magnetic interaction between the coils and magnets, the faster the motor. However power is lost, so ground speed (which involves LOTS of resistance) is highest with a good balance of power vs speed.
2. Winds/Wire (coils)
One of the biggest determining factors in motors is the wire- How many winds and What gauge wire. In general, bigger gauge wire and fewer winds will make a faster/more powerful motor. The downside (limitations) are current flow- the less resistance (less length, bigger gauge), the more current it’ll draw. There are limits to what the batteries and electronics can handle. Second is heat. Two things determine the strength of an electro-magnet- The length of the wire and the current flow through that wire. By using less wire of a larger gauge, much more current can travel, so power is gained or maintained. The material that makes up the wire also effects the current. Most wire is copper, but some use silver wire, which is more conductive and will increase the current and power accordingly.
3. Armature
There are several styles of armatures. Here’s a description of the common versions you’ll encounter:
There are several styles of armatures. Here’s a description of the common versions you’ll encounter:
Standard/Stock:
A typical “short” armature. RS motors use these. Fairly high spinning speed but low power. Approx 8mm long using 16 laminations.
Long arm:
A longer version of the standard arm. High power, slightly reduced speed. Approx 11mm long.
Spiral Arm:
A long armature with the laminations twisted to make a slight spiral. This reduces the effective magnetic force and thus increases rotation speed. Behaves similar to removing a few winds from the coils of a long arm.
Slotted Spiral arm:
A spiral arm with some of the middle laminations removed to make breaks or “slots” in the rotors. Typically available with either 1 or 2 “slots”. Both version perform similar, 2 slots is a little more extreme than one. The slots reduce the electro-magnets permeability, and thus reduce the magnetic strength making the motor spin faster. They also promote cooling. Performs similar to removing a few wraps from a normal spiral arm.
Spiral arms can help reduce the startup current because they spin faster than other arms with the same number of wraps, so more winds can be used to achieve the same speed.
4. Commutator
Two types of commutators are also typically used.
Two types of commutators are also typically used.
Standard/stock:
What RS motors use. Copper contact pads set on a small diameter shaft. Gets the job done, but not very efficient.
Fat Commutator:
Comes in either Copper or Silver. Silver is more conductive, but only a thin coating is used, which typically wears off fairly quickly. Silver also helps reduce arcs/sparks and prolongs the brush life and reduced heat. “Fat” is referring to the diameter of the comm, which is several mm larger than stock. This improves the connections and reduces shorts/sparks that happen when the brushes move between contact areas. Improves torque and helps cooling.
5. Brushes
The brushes get power to the armature. This is a very important job. Several varieties are available:
The brushes get power to the armature. This is a very important job. Several varieties are available:
Stock/Standard:
Carbon:
Typically ~20% more efficient than stock. That means 20% more power will actually get to the motor. Faster and more powerful.
Silver:
The most conductive, but unfortunately a softer metal. With high heat they will shrivel. Good for use in 4.8v high wind applications. Brushes for Atomic EGR can pictured.
Upgrading brushes is a very important part of motor tuning and provides amazing gains for the cost.
Custom/self Made Brushes:
Custom/self Made Brushes:
Layers of copper brush provide more current flow to the motor giving more power and increases the speed/torque (depending on the type of motor) of a motor.
6. Magnets
As a result of the “generator” effect explained above, stronger magnets will reduce the motors top speed. However, it can also add a lot of power to the motor. Most very hot motors use neo’s to help make up for the low turns. Stronger magnets will also reduce the current draw of the motor. Remember that a fast motor is useless if it doesn’t have the power to push an xmod.
As a result of the “generator” effect explained above, stronger magnets will reduce the motors top speed. However, it can also add a lot of power to the motor. Most very hot motors use neo’s to help make up for the low turns. Stronger magnets will also reduce the current draw of the motor. Remember that a fast motor is useless if it doesn’t have the power to push an xmod.
Stock magnets/ An-isotropic Ferrite- Weak magnets.
An-isotropic means the magnetic particles are not lined up and thus is very weak. Provides high RPM with VERY little power.
Isotropic Ferrite:
The common “spinbrush” magnets. Isotropic means it “looks the same (identical) in all directions”. The magnetic particles are lined up and thus strong. Provides a decent amount of power without sacrificing too much speed. Great magnets for motors with winds in the 30ies and up (maybe upper 20ies).
Neodymium Magnets (aka Neo mags or neo’s):
Neodymium is a rare natural metal that has very strong magnetic properties. These will provide great power, with some loss of top speed. Used in most motors with <30t.
7. Motor Can
The can holds everything together and can play very important roles in cooling and efficiency. The motor is the most important place to reduce friction. Every other part of an xmod is geared down. This part has the highest RPM and lowest power.
The can holds everything together and can play very important roles in cooling and efficiency. The motor is the most important place to reduce friction. Every other part of an xmod is geared down. This part has the highest RPM and lowest power.
Stock Can
Metal brushings that the arm rubs on when spinning (Tip- lubricate each end with a little oil). No cooling vents. Once again, it gets the job done, but lazily.
Bearing Endbell (aka BB endbell):
A replacement endbell with a ball bearing. Helps to reduce friction without having to change the whole can, and good for those nut’s who melt endbells.
Bearing can(aka BB (Ball Bearing)):
A typical can with ball bearing to reduce friction. Typically has vent holes to help cooling.
Aluminium Bearing Can:
Give faster cooling, act like a heat sink to high temp motor.
EGR “Atomic” BB can:
Two large vent hole right above the rotors to help facilitate cooling (this feature is currently removed). But the most distinctive and unique part is the endbell. It is entirely open to help cooling, ease of changing brushes, and the application of comm drops. It also holds the brushes in a different manner to ensure they stay opposite each other with fat comms. Special brushes are required for this can (typically comes with the can).
Timing:
Timing changes are accomplished by rotating the commutator in relationship to the rotors. This changes the point in rotation when the coils turn on.
Stock Timing (Comm tabs in between rotors):
The coils turn on leaving one magnet until entering the next. This happens for every coil both top and bottom of the motor.
Timing changes are accomplished by rotating the commutator in relationship to the rotors. This changes the point in rotation when the coils turn on.
Stock Timing (Comm tabs in between rotors):
The coils turn on leaving one magnet until entering the next. This happens for every coil both top and bottom of the motor.
Advanced Timing (rotate Comm CCW from comm end):
This makes use of a slight forward EMF to actually increase the voltage through the coils at a certain point. Not very efficient, but can be very useful. Increases speed, decreases power. Please note- I have heard different opinions on power. The decrease in power theory seems more accurate to me (several respected sources have performed tests).
This makes use of a slight forward EMF to actually increase the voltage through the coils at a certain point. Not very efficient, but can be very useful. Increases speed, decreases power. Please note- I have heard different opinions on power. The decrease in power theory seems more accurate to me (several respected sources have performed tests).
Retarded Timing (rotate comm CW from comm end):
Useless. Less efficient than either stock or advanced timing. Big loss of power.
Useless. Less efficient than either stock or advanced timing. Big loss of power.
I want to personally thank ScienceMike, Ph2t, Flashsp-2 and everyone who asks questions for teaching me this info over the last couple years. Most of this info I learned just by reading posts on xmods forums and I hope this compiles it into a more concise, easy to read post. Some of what I’ve written is very advanced, and I didn’t go into too much detail to save space/time. If you don’t understand something, please ask about it. We all will learn. Pictures are courtesy of Maine-iac-motors, Performance Xmods, FreestyleXmods and Radio Shack. Big thanks to those shops and their owners!
Enjoy and keep modding,
- creative
- creative
main source: http://www.xmodworld.com/node/15403
