Make Architecture



Involute Gear Plug-In Demo

  • Draw a circle in Rhino which will be the pitch circle of the gear.

The pitch circle is an imaginary circle on a gear that divides the gear teeth into addendums and dedendums (see diagram below).

For example:

I drew a circle with diameter equal to 6″.

  • Run the Involute Gear Plug-In. You will be asked to select the pitch circle of the gear.

  • You select your circle and press Enter. You are provided with the following options:

The plug-in demonstrates a summary of the data of the gear, given the selected circle and the default values of the plug-in. You can edit any of these values.


the number of teeth of the gear


the module of the gear m is the ratio of the diameter d of the reference circle divided by the number of teeth z:

module = reference diameter/ number of teeth     or     m =  d/z


The circular pitch p (the pitch is the distance between equivalent points on adjacent teeth) of a gear is defined as:

circular pitch = circumference/ number of teeth     or       p = π*d / z


Pressure angle is general the angle at a pitch point between the line of pressure which is normal to the tooth surface, and the plane tangent to the pitch surface. Pitch point is the point of intersection of the pitch circle and the profile of the tooth. See diagram below:



Defines the bevel angle of the gear. By default is set to 0.


Number of points that define the involute curve of the gear tooth.

  • I defined my gear by setting the number of teeth to 20. The gear is generated and the summary of the new data is displayed in the command window.

  • If you want to design a second gear that will mess correctly with your first gear you have to make sure that they have the same pitch.

p1 = p2

If we assume that we have one gear with pitch circle diameter d1 and number of teeth z1 and another gear with pitch circle diameter d2 and number of teeth z2 then the relation that connects the pitch circle diameter and the number of teeth of the two connected gears is the following:

If:   p1 = p2


π* d1 / z1 = π* d2 / z2

d1 / z1 =  d2 / z2

d1 / d2 =  z1 / z2

  • You have to make sure that:

The pitch circle passes through the point where the teeth touch when one gear meshes with another.

The two pitch circles come in contact (See diagram below)


  • In Rhino:

Generate the pitch circle for the second gear. Run the Involute Gear plug- in. This time, after you have the pitch circle selected, set the pitch value equal to the pitch value of the previously generated gear.

The pitch value of my previous gear was 0.942.

I set the same value for the current gear.

Given the input pitch value, in order to keep a whole number of teeth the system will adjust the diameter of the pitch circle.

Rotate each of the gear so that their pitch point ( point of intersection of the pitch circle and the profile of the tooth) is on the same line.

Bring the pitch circles in contact.


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Instructor: Nick Gelpi TA: Skylar Tibbits TA: Varvara Toulkeridou
Class Times, Monday, 1-4pm - room 5-216
4.184 is an intensive introduction to methods of making explored through a wide range of brief but focused 1-week exercises. We'll engage the real and leave behind representation in the focused context of this class gaining skills for utilizing a range of fabrication machines and technologies from lasercutting, waterjet, 3D printing, welding, formworking-molding, casting, gears, joints and composites.
In this workshop we'll constrain ourselves to the territory of the 1:1. Students will represent architectural constructions at full scale and develop a more intimate relationship with technology by engaging the tools and techniques that empower us. We will gain access to the most cutting edge machines and technologies in the MARS lab at the Center for Bits and Atoms.
The second layer of information for this course will be to look at a series of case studies in which construction methods and technologies have played a dominant role in the design process .
Over the past 20 years, architects have focused on the technology of representation to create new ideas of what architecture could be. Looking back today, much of that research failed to substantially change the way we design buildings by focusing on apriori formal configurations. This class makes the contention that this failure comes from a lack of considerations of the potentials within fabrication knowledge. We look to the future of what building might become, given the expanded palette of personalize-able technologies available to us as architects. Students will participate in curious technological and material investigations, to discover the potentials, known and unknown, for these various technologies.
The sub-disciplines of what's drawn and what's built have been compartmentalized and disassociated as the representational tools of architecture have distanced themselves from the techniques of making. At the same time the technologies for “making” in architecture have provided us with new possibilities for reinventing how we translate into reality, the immaterial representations of architecture.


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