1.2_press fit curves [S chair_design+CNC cut]


The shape of the curving chair comes from the measurement of my own body (with Alex Farley’s help). We quickly traced the quads of the curves and I then modeled this in Rhino.

Editting process of the two curves shape.

James (the TA) helped me to model the ribs tangent to the curve using his wizard Grasshopper skill. A script he developed allows for the Rhino model made into cut files (with 10% tolerance) – we decided to go with 0.48″ of maximum material thickness; that’s 0.53″-0.55″ with the script tolerance.


The final cuts were executed on a piece of 4′ x 8′ (48″ x 96″) plywood using the newer ShopBot CNC machine with 1/4″ drill bit. Below are screen-shots of the setting up process we did in the PathWorks program previous to the cutting action.

When checked, we found some unclosed curves which confused the cut path in deciding whether one side is inside or outside.

Instead of going back to Rhino, we use the join command to close the curves and added the T-bone corner detail.

However, later on we found that this is not an ideal option as ShopBot only cuts inside or outside the closed curves instead of understanding whether the logic of the notches.

First cut path for the (inner) notches only.

Second cut path for all the (outer) curves.

After hitting the calculate button, we set up the zero positions for the X, Y and Z axes. ShopBot has an advantage in this that there’s a metal plate and an alligator clip which finds caliper the Z axis on the material itself; with the TechnoCNC, you have to judge by eyes.


At the speed of 16000 rpm, it took almost 1.5 hours to fully cut the pieces.

This shows the problem of closed but untrimmed curves mentioned above. Now the pieces require a post-cut touch up which will not only involve sanding, but also cutting process.

A benefit of this type of (mistaken) cut technique is that the inner notches actually held the pieces in place whist the machine drilled the curve profiles as opposed to cutting everything at one go which will eventually displace and shift hence less accurately follow the cut profiles due to the drill rotational forces.

4.196 Special Problems in Architectural Design Complete Fabrications Nick Gelpi Mon-Fri, Jan 5-7, 10-11, 13-14, 18, 20-21, 24-25, 27-28, 01-04:00pm, 3-402/7-432studio, 1st mtg Wed 1/5 Pre-register on WebSIS and attend first class. No listeners Prereq: Permission of instructor ; Yr-1 MArch students who have completed 4.123 only Level: H 9 units Standard A - F Grading Can be repeated for credit Lab Fee: 150 A comprehensive introduction to methods of “making” explored through a wide range of brief but focused exercises. Skills = developing complex geometries from flat components; fine-tuning press fit construction, molding and casting, and making repeatable molds for customization. A two-part workshop, the first half will contextualize contemporary tools and techniques within the trajectories of historical case studies of building, combined with hands on familiarization of tools. The second half will implement the tools of our workshop in the context of Design. Working on group design build process for three MIT 150 FAST installations, students will test and influencing designs through the instrumentality of production. These hands-on design build projects are intended to produce reciprocity between skills and design, making more complete the problems of fabrication. Subject limited to year-one MArch students who have completed core-1 studio. Contact: Nick Gelpi, 9-224, 253-9415, -


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