Fucking Machine Design

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The glorious fucking machine is a popular project, and one solved in many different ways. Some of the common problems include range of movement, motor power, motor control, and many others.

Sex Machine Design Challenges

Motion Source

Prime Mover Advantages Disadvantages Learning Resources
DC Motor
  • Simple to power
  • Easily Reversible
  • Plentiful, easy to upcycle
  • Many sizing / gearing options
  • Power controls are plentiful and easy to implement
  • No Positional Control
  • Small inexpensive motors lack torque and likely require additional gearing

Stepper Motor
  • Position control possible!
  • Fine control of motion
  • Control complexity
  • Often low torque, will need additional gearing

Jeremy Fielding - Beginners Guide To Using Large Stepper Motors: #087

Servo Motor
  • Position control possible!
  • Fine control of motion
  • Control complexity
  • Cost, servos in the size required to drive most sex machines are generally targeted towards industrial customers.

Pneumatic Cylinder
  • Mechanically Simple, already produces linear motion
  • Powerful
  • Control can be controlled without electronics (pneumatic logic)
  • Requires pressurized gas source
  • Dangerous levels of force need to be avoided

Mechanical System

Rotary to Linear

Most motion sources described above start often with a rotary motion. Generally, most machine designs will want to convert that rotary motion to a linear action. There are a few ways to accomplish this.


A fair number of machines solve the problem of converting a rotary motion to linear using a crank. This crank is often in the form of a disk. Attached to this will be an intermediate linkage which then attaches to a final shaft. The final shaft is constrained to a single plane, and the intermediate shaft allows for the change in angle as the crank shaft rotates.

Example of Crank Mechanism

The stroke length is 2x the radius of where the intermediate shaft connects.

The force of the motor is reduced as this radius is increased.

Rack and Pinion

Rack and pinion animation.gif

The rack and pinion setup is like a spur gear, with the larger gear laid flat. This is useful setup that has some control challenges.

Notable Uses:

Linear Motion Control

With the rotary motion made linear, generally there is a need to constrain the motion.

Linear Rails, Drawer Slides


Simple power controls

DC motors are widely used because of their ability to be easily controlled. Voltage applied to the motor will start and maintain motion. Reversing the polarity of the voltage supply will reverse the motor.

Most sex machines utilizing DC motors will incorporate a speed controller. DC Motors speed control is accomplished by varying the voltage to the motor. DC motors described in this section are assumed to be Brushed Permanent Magnet DC Motors. Although the concepts are similar for other types of DC motors, there may be some specific challenges related to other configurations. Brushed Permanent Magnet DC Motors are the most common to be found in hobby sources, however brushless motors are now common in tools. These motors are usually AC Polyphase Permanent Magnet motors and require an appropriate controller to operate.

DC Speed controls can be found from many online retail sources, this allows control of DC motors without having to build your own controller.

Sizing A DC Speed Controller

The speed controller will have to operate at the correct voltage for your device. Often the DC controller is separate from the voltage source, so it will have a range of allowed voltages. Common voltages for hobby motors are 12vDC and 24vDC. These voltage levels are safer under normal circumstances. 12vDC will be most common and recognizable for hobbyists, however as 24vDC devices are common in industry it is possible to find many options.

The power rating of a DC Speed Controller will be expressed in watts or amperage (current). Watts are (in the simple form) [ Voltage x Current = Watts ] so it is possible to work with either value. The amperage of the motor will be specified as Full Load Amps (FLA) or Watts or Horse Power. To convert from HP to watts, multiply by 746.


1/4HP motor rated for 24vDC is [0.25HP x 746w = 186.5w]
This lets us calculate the amperage at 24vDC, [ 186.5w / 24vDC = 7.8A ]
For this example we would need a controller capable of at least 7.8 amps at 24vDC
It is important to have additional current capacity, so it would be advisable to multiply the required by at least 1.25, giving us 9.75A minimum design requirement.


Reference numbers

These numbers are just to give you the ballpark of where a machine could be. Your preferences may vary.

Thrusts/strokes per second
For penetration - about 0,5 - 3 strokes/s or 30-180 rpm
Thrust length
For penetration - 3 - 15 cm depth
Thrust Torque
For penetration - 3 Nm
Noise level
Noise reference
Noiseless < 28 dB
Quiet < 35 dB
Discrete < 45 dB
Bearable 45 - 55 dB
Noisy 55 - 65 dB
Industrial > 70 dB



Other adoptions

Forced Oral

Slapping / Spanking Machine



Open Source Machines

Commercial Machines