Tuesday, October 12, 2010


A helix is actually a very simple shape for parametric modeling. Think of it as a segment of a shell that is rotated and translated (offset) with each increment. You can make one in Autodesk Revit very easily.

Create a family with a generic model. You can make an extruded box drawn in an elevation view. I drew a reference line to define an angle through the family center. Rotate the box to align with the reference line. Create a parameter for the angle. Make sure that its type is "angle". Draw a angular dimension on the reference line and associate it with the angle parameter. Create an index and a angle_increment. Create a formula for calcuating the angle of rotation from the index and angle increment. That's all there is to the family. (I have added some extra parameters in anticipation of changing the radius of the helix and the size of the patch.)

In a project file, you can insert the helix facet. Insert 20 or 30 copies. Change the index of each copy and it will spin around the axis to the right location.

Monday, October 11, 2010

Simple parametric family in Revit

One of the coolest things about Autodesk Revit is the ability to make shapes that are governed by formulas. This is the essence of algorithmic design, and while several other tools on the market are more flexible and powerful than Revit in this regard, there are interesting things one can do in Revit's BIM environment.

There are several concepts that one must grasp. First, a new Revit family should be drawn using reference planes and references lines. It is easier to impose constraints on the reference planes than it is on the model lines and model geometry (model lines tend to lock to reference planes and points by default and it can be unpredictable or unwanted.) Use dimensions to establish the essential geoemtric relationships of your family, such as lengths and angles. Second, the Revit family must have named parameters. You associate these named parameters with the dimensions and angles in your geometry and model. Third, there must be an "index" value that triggers the formula. Typically you will type in the index value and then the formula will calculate the geometry parameter. Finally, you must enter a formula using the index (or indices) that will calculate a geometric relationship.

Once a family has been created in this way, you can insert multiple instances of it into your project and then set different values for the index. The geometry will alter for each instance based on the formula.

Below you will see the same project file after changing the formula in the beam family.

Here it is with the cosine determining the angle of the beam. (I am sure that I have not done this in the simplest way, but I added the extra calculated parameters just to convert the units of the parameters so that the formula would not complain about "inconsistent units". Apparently the cos function requires that the input value must be in degrees. Input value in integer or number does not work.)

Monday, February 22, 2010

Making cut paths using Revit

We have been cutting wood with our CNC router
for several years, both in two axis applications and three axis. However, we have rarely cut other materials and I suspect few people realize that we
can cut almost anything. I decided to do a project with aluminum to show off the capability of cutting other materials. Besides, anything you make out of aluminum will look beautiful.

The project is to design a canopy over a train station platform that would be 240 feet long. Build a model of the structure at ½” = 1’. The models will be ten feet long which is an awkward size to move around. Consequently, the models must be manufactured in two 5 foot sections.

Aluminum cost us about $215 per sheet of 3/16” thick by 4’ by 8’. It is not cheap but it is not prohibitively expensive either. I used grant funds to buy a sheet for each of my students, and some for me too.

Cutting aluminum is just like cutting MDF or plywood except the particular settings for revolutions per minute and linear feet of movement are different. Chuck called his suppliers and other experts and also experimented to find good settings. Slow is good, plus we used a blower to air cool the bit and push the shavings away.

One of the problems that we encountered was that the bit lifted the aluminum sheet off the bed and then mangled it. We designed the locations of drill holes in AutoCAD so that we could screw the sheet firmly to the sacrifice board without damaging the pieces of the model.

Just like cutting MDF or even laser cutting, I needed to create a cut path sheet in AutoCAD to load into MasterCAM for running the CNC router. The AutoCAD drawing needs to be the accurate size of the model (120’ in the design should be 5’ in the model) and all lines need to be polylines (PLINES). It is helpful to have a 4’x8’ rectangle drawn to represent the sheet of stock material.

My process involved making the model in Revit. I created sections through the model at the location of every part profile that I would need. I then used a sheet template to create a new 4’x8’ sheet and laid out all of the parts on the sheet carefully to avoid wasting material.

There are numerous steps to convert the Revit sheet to the DWG file, but it is really pretty easy. The sheet can then be exported to a DWG file. The file will then open in AutoCAD 2010 as a Paper Space sheet. This peculiar command will save a Paper Space DWG into a new Model Space flle.

Each part exists as a BLOCK, so it must be EXPLODEd. The first time through, the EXPLODE command produces SPLINES, ARCS, LINES and other objects. The PEDIT command will convert a SPLINE into a PLINE. I recommend converting all SPLINE segments into PLINES and then using PEDIT Join to recreate closed loops. If you join a spline into a PLINE then the spline will not become a proper curve. So convert the spline to a pline first and then join it.

I used the OFFSET command to create new paths to cut holes in the largest elements to make them lighter and more elegant.

The DWG drawing was then saved as a DXF 2004 file because that is what MasterCAM wants to import. It imported without errors and Kyle rotated it in MasterCAM to the orientation that the router expects. He set the tool cut depth, linear speed and revolution speed and designated the order to cut the profiles. When designating the order, it made sense to first cut all of the holes so that we could put screws in each hole, and then pick parts in a proximate pattern to avoid moving the head needlessly. Cutting at first produced rough and rather nasty edges, but after adjusting the cut settings and adequately securing the stock the cuts came out beautifully. Here are the parts laid on tables awaiting assembly. The scrap is also beautiful and reminiscent of a dressmaker’s remnants.

It is all pretty easy and straightforward. I am dying to see 110 feet of aluminum canopy models lined up outside Langford Architecture Center!

Sunday, February 14, 2010

More form making with Revit

Here are some of the sketches that I have produced with Revit to model a train station canopy.

The basic idea is to make a swept blend form that has two profiles parallel to the track and a path perpendicular to the track. The form can then be chopped into various sectional ribs and purlins that create the primary and secondary strucure of the canopy.

One conceptual trick is to use the offset command on the profiles P1 and P2 to make several profiles and eventually several concentric shells. One shell will eventually be the purlins, one shell will be the beams, and perhaps a final shell will become columns. If you edit the basic founding curve then you have to recreate all of the subsidiary profiles. That is not difficult, but it seems like there should be an easier way.

Once the form has been created and tweaked and shaped, you need to cut it up to make the structural mmbers. I built a new family of void boxes that can subtract away the bays leaving just the structural members. The family is parameterized to include bay spacing, a bay depth, and a structural thickness. It also has a parameter that works with the array object to repeat the bays.

One instance of this bay family cuts the purlin shell into individual purlins. Another instance cuts the beam shell into beams. A third instance cuts the column form into columns for each bay.

I am not really satisfied with the columns. I cannot figure out a way to shape the columns so that they are responsive to the roof form above them. Of course, one could just use form making tools on each column individually.

I have posted a bunch of screen dumps that might serve as inspiration.

Monday, January 18, 2010

The Case for Building Homes in Architectural Education


In 2007, the Department of Architecture adopted a track focused on home architecture as one of three alternative paths to completion of the degree of Bachelor of Environmental Design. Under the curriculum devised at that time, students are provided with a broad suite of alternatives that include a traditional and conventional path in the Architectural Studies Track, an exploratory and self-directed path in the Research Track, and a construction-oriented path in the Home Architecture Track. While the Research Track largely consists of a customized degree plan of 13 credits in the senior year, the Home Architecture and Architectural Studies Track are based around studio sequences and integrated technical courses.

The Home Architecture Track consists of an eight credit experience in the fall semester and five credit studio in the spring semester. The fall unit combines ARCH 407 design studio with ARCH 432 and ARCH 436. The intention is that students will conduct a construction project at the Architecture Ranch and will gain hands-on experience with construction, structures, systems, detailed design, and project management. The spring semester consists of a final design studio (ARCH 408) that allows students to apply the practical skills that they have learned to produce innovative designs for homes that can then serve as plans for construction in the subsequent fall.


There are several motives for introducing the Home Architecture Track. The BED curriculum dates from the late 1960’s and is long overdue for a deep reexamination within the context of 21st century social needs and technological opportunities. The tri-partite form of the new curriculum allows the department to preserve the tried and true conventional sequence of courses while experimenting in new curricular forms. The Home Architecture Track is one of the experimental forms that has the potential to achieve a national and international reputation for excellence and help our department to establish itself as a leader. A minor consideration is the existence of the Mitchell endowment that provides funding and expects a commitment to residential design and construction.

Similar programs already exist at other schools throughout the United States. The Department of Energy Solar Decathlon Competition has been run through several cycles and has included up to 20 schools in each cycle. Several schools, such as University of Colorado, Virginia Tech, Cornell and Puerto Rico, have repeatedly participated in the competition, demonstrating a deep and strong commitment to home building. The list of participants is shown at http://www.solardecathlon.org/

Other schools have a commitment to home building independent of the Solar Decathlon competition. The University of Kansas has operated Studio 804 since 1995, building 14 projects of startling beauty. Auburn University is highly celebrated for its Rural Studio, which often involves building houses. The University of Kentucky has also built several houses under the leadership of Professor Greg Luhan, including the Resonance House, also seen in a video and the S.ky Blue House. The Yale building project was conceived at Yale University by Charles Moore, and has built houses for 40 years. Building houses in an architecture school has become a mainstream activity that is extremely attractive to students, former students, funding agencies, and the general public.

The regional context for Texas A&M establishes further motive. Hurricanes of recent years have devastated the housing stock in Texas, Louisiana, Mississippi, and Mexico coastal regions. The recent earthquake in Haiti is another example of the clear need in our region for disaster relief and provision of affordable houses to disadvantaged communities. As a land grant university, Texas A&M has a mission to provide service to the public and particularly the lower income residents of our region who have been harmed by these events. Recovery will take decades. Our department can seize the opportunity to lead recovery and serve the public in a very genuine and tangible way by helping to rebuild devastated communities and strengthen communities that are at risk.

In addition, the colonias of the border region have long been a focus for college research and service. These communities continue to have extreme needs to develop of residential resources.

Focus on innovation in residential architecture has strategic value for the department in two key areas. Green architecture and the concept of triple bottom line sustainability have come into strong focus as national and global priorities for current and future development. Global warming is a dominating issue of the 21st century (http://www.pewclimate.org/docUploads/Key-Scientific-Developments-Since-IPCC-4th-Assessment.pdf). The Intergovernmental Panel on Climate Change (IPCC) has identified decreasing energy consumption in buildings as the highest priority for immediate action in slowing the trend toward global warming and the reducing the impacts of climate change. Energy efficient residential architecture is a key part of surmounting the challenges that society faces from climate change. Texas A&M has an obligation to search for solutions to these problems. Demographic changes in Texas, the nation and the world are also a key driver for focusing on residential design innovation. Demand for housing and new residences will increase rapidly due to population increases, population migrations, disruptions due to environmental stress, and other factors. Texas A&M should provide leadership in finding solutions to the problems that will arise.

As compelling as these motives are, perhaps the most important motive for introducing the Home Architecture Track is the educational experience that it provides to students. Beyond the technical knowledge and skill obtained in architectural education, our department can provide experiences that are life-changing in the maturation of individuals that they offer. The Solar Decathlon effort that culminated in 2007 was a highlight life experience for those who participated. Students learned to work as a team, learned to accept responsibility, learned to provide leadership, learned to follow leadership, and learned how to achieve something bigger than the individual. They learned all of these within the context of architecture and construction. These are lessons that are at the core of behavior of a competent and successful architect. No other experience that our department can offer comes close to the experience of building a house in preparing a student be an architect and designer.

Resource requirements and availability

The Home Architecture Track will require reassignment of resources and generation of new resources, but should not adversely impact any other programs within the department. Personnel assignments, space allocations and funding availability are all needed.

The Home Architecture Track consists of 4 courses: ARCH 407, ARCH 408, ARCH 432, and ARCH 436. Accommodating one cadre of 16 students should require approximately 1 FTE at the typical teaching load of two courses per semester per faculty member. The skills required of faculty members probably suggest that the load should be spread over two or three faculty members. An efficient offering of the courses and the needs to achieve sufficient student-power to construct a house may more realistically require two sections of 16 students.

A willingness to redefine curricular content and expectations to accommodate the objective of building a house can lead to a relatively straightforward implementation of the track. The structures component should focus upon residential construction and structures, such as lightweight wood framing, wood joinery, slab-on-grade and simple foundations, SIP construction, cabinetry and fabrication. The systems component should focus upon residential systems, such as single zone mechanical systems, solar hot water, photovoltaics, simple water and sewage systems, home theaters and audiovisual design, and residential sustainable systems. Skills in these areas are typically within the expertise of architects, home designers and tradespeople rather than professional engineers.

Faculty assignments could be achieved as follows:
Fall Semester
ARCH 407-501, 16 students, Faculty 1
ARCH 407-502, 16 students, Faculty 2
ARCH 432-501, 32 students, Faculty 1 or Faculty 3

ARCH 436-501, 32 students, Faculty 2 or Faculty 4

Spring Semester
ARCH 408-501 Faculty 1
ARCH 408-502 Faculty 2

The fall semester staffing presents some challenges. A most efficient staffing would make use of two faculty members, one who combines expertise in design, structures and construction, and one who combines expertise in design and building systems. Alternatively, a specialist in structures and construction and a specialist in building systems could be assigned to work with two design instructors. Outside consultants in residential building technology could be provided to enhance the educational experience. For example, a contractor with expertise in photovoltaic system design and installation could provide a hands-on workshop, and be either uncompensated or provided with a stipend.

Graduate students, if carefully chosen, may be able to provide very tangible support through GAT positions. Risks are significant that the fall semester house building effort would be overly demanding of the time of a graduate student. It may be inadvisable to hire an M Arch student for this position as commitment to completion of the M Arch program should take precedence for that student. However, many of our PhD students have substantial experience in architectural practice or even building construction and could be of great support for the ARCH 407/432/436 sequence.

Another model for staffing could include hiring an expert from practice, either architectural practice or construction practice, to provide instruction and guidance during the fall semester. Funds from the Mitchell endowment could be devoted to this position.

Space needs are not exceptional. ARCH 407/432/436 can be taught in a normal studio setting with special activities at the Architecture Ranch for actual construction. If permission can be obtained, the sequence can be held entirely at the Ranch, relieving some demand upon space on the main campus during the fall semester, when demand is highest. ARCH 408 can be taught in a normal studio setting.

Funding for the house construction is probably the main barrier. However, informal conversations with students and former students suggest that building a house is an exciting and attractive prospect that could be funded through private donations. Cooperation from local builders and even regional and national builders is also highly probable. Contributions from material suppliers should also be achievable. A concentrated fund raising effort will be necessary to raise the funds. Mitchell funds can be used in the spring of 2010 to undertake a fund raising effort.
The Brazos Valley Affordable Housing Corporation has offered funds for building an affordable house (approximately $80,000). The house could be built at the Ranch and then moved to a lot for sale to a client. BVAHC suggests that it could be kept at the Ranch for up to a year to enable testing and monitoring before it is moved. Alternatively, our department could build the house on site or even design the house and provide plans to BVAHC for construction by them.

The funds needed for a meaningful experience are not overwhelming. Recently, the Auburn Rural Studio built a small house for $20,000. A goal of raising $100,000 in materials and cash contributions, coupled with funds from the BVAHC, should be adequate for a first prototype. This first prototype should be modest in size, use relatively conventional construction technology, and relatively conservative building systems. By setting our sights appropriately and avoiding high risk through too much experimentation, the program can get off to a solid start.


In summary, the potential benefits are substantial while the costs are significant but not excessive. The primary benefit is an enhanced educational experience for the students who participate, increasing their confidence, leadership ability, and practical knowledge of architecture. An additional benefit is the public service provided by a continuing program of building affordable and prototype homes. The research benefits are also substantial, as we can use the homes as test beds for innovation in energy efficiency and sustainable design. The public relations benefit could be the most important value, as a continuing program can achieve national attention, attract support from agencies, inspire students and student applicants, and rally former students.


At this point, January 2010, the recommendation is to proceed with the Home Architecture Track by implementing the following steps:

  • Incorporate courses into the course schedule for Fall of 2010.
  • Conduct a competition to select a design for construction from the products of one or more studios in the spring of 2010.
  • Commit administrative leadership and resources at the department and college level to raise funds for construction of the first house.

The Home Architecture track can become a highlight of the Department of Architecture and help propel us to achievement of the consensus Top Ten position that is our stated goal.