http://www.timefold.com/guests/hoco/cgi/nosecalc.cgi

To use the calculator you create two data files on your computer. Then you browse for them on the nose calculator page, select what you want to generate (e.g. an image, labels, etc.) and then click "Do It Now".

To create these data files you'd need to design a tensegrity structure. Read about that on the Building a Model page.

Once you've uploaded a pair of files the nose calculator will remember them for you for up to a day, as long as you don't leave the page or upload new file, whichever comes first.

When generating images, be sure to hold down the shift key and click reload in the window displaying the image if you have already generated an image once. This ensures that you see the latest version of the image, and not the one cached in your browser.

If you want to keep an image, put your cursor over it and choose "Save Image As..." from the menu that appears when you hold your left (or only) mouse button down.

The nose calculator is based on the premis that you are building a symmetrical structure out of struts which are connected together at verticies whose coordinates you have reflected in your vertex data file. It assumes that the struts will need some extra length so that a hole can be drilled in its end where the vertex actually goes.

For more information on how struts can be cut and made into a structure, see The Home Dome -- lots of pictures of the whole process from measuring struts through final assembly.

The measurements of X, Y and Z for each vertex are points. The nose calculator assumes that the struts will be joined together by drilling a hole near each end of each strut, and connecting struts through those holes using carriage bolts. So, the nose calculator needs to know how much length needs to be added to each strut so the hole is far enough from the end of the strut that there is sufficient mechanical strength. That is, if you drilled too close to the end, the carriage bolt might tear through the end of the strut during one of those 70 MPH dust storms that have been known to hit the playa.

So, the nose calculator allows you to specify the length of material to be added to each strut and this is called the "end bonus". An end bonus of 2" means that you are planning to drill the connecting holes centered 1" from the each end of the strut.

The Margin for Error value allows you to input a reasonable margin for error in measurements you'll be making when you cut. This is useful because would you want to not use the remaining portion of a strut simply because it was\ 0.0001 too short? No, you'd look at it and say, "What luck! It's already the right length!". If you think the closest you'll be measuring is 1/16" then enter the decimal equivalent of that.

The kerf width measurement accounts for the thickness of the blade or abrasive cutting wheel you are using to cut the conduit. If you are using a pipe cutter (the kind they often use on plumbing pipe and even copper tubing) then you may find that you have a kerf of 0 -- that is, no material is lost when a cut is made. But any kind of sawing action will remove material equivalent to the thickness of the blade. The nose calculator accounts for this because when you add up all the kerfs, it can be quite significant in any given length of conduit. This is especially true because the nose calculator endeavors to place struts in a given conduit to minimize waste. Sometimes the waste in a given length of conduit is less than the sum of the kerfs. Without taking them into account there wouldn't be enough conduit left for the last strut in that case.

The fact that the nose calculator assumes your structure is symmetrical means that you only have to measure and enter data for roughly half of your verticies. This saves a lot of work, and also allows the nose calculator to render half of the image when that makes sense (such as for a side view). Some of the struts will be on the line of symmetry, so the struts data file lets you identify these by noting that only 1 of them is required. The nose calculator treats these slightly differently than those that are mirrored left and right.

At this point there is no way to create a non-symmetrical structure using the nose calculator, but at some point in the future I might adapt it to do so.

The nose calculator also lets you specify a list of struts whose coordinates you want to see. This is useful to learn the size or position of various parts of your structure. For example, the Desert Nose has a deck inside. When I ask for the coordinates of one of the struts in the deck I can read the height of the deck as the Z coordinate of the strut I chose.

The nose calculator examines your vertex data to produce dimensions (Length, Width, Height), based on the maximum values for the Y, X and Z dimensions respectively. That's right: Length is determined by Y, Width is determined by X, and height is determiend by Z. This is because when I taped my Desert Nose model onto 10 squares/inch graph paper to measure its verticies, the X axis was in front of the nostrils and spanned left and right. The Y axis when down the centerline of the nose, from between the nostriles back to the furthest portion of the nose bridge. The Z axis was up out of the graph paper (normal to the sheet). That is, the Z axis was its "height".

I measured my vertexes by creating a tiny plumb bob. I You can make one by taking a needle and threading some thread through its end. Then taking a lead fishing weight about the size of a BB and clamping it on 3/4 of the way away from where you fastened the thread. When you hold the thread the needle should point straight down.

I'd hang the thread over the vertex and use my finger to dampen the swinging. When it was still I'd make a dot on the graph paper right under the point of the needle. This would give me the X and Y coordinates. For the z Coordinate I'd use a metal ruler I had which had its measuring region begin right at its edge. Another technique I'd use was to take two drafting triangles and use one as a base and one as a sliding measure. Then I'd make a small pencil mark on the base triangle when the sliding measure lined up with the position of the vertex. Then I'd measure the height as the distance from the edge of the base triangle and the mark I'd made.

Once you make your measurements and create your data files, you can generate some images to look for errors in your data. I found several errors in my data including:

• Incorrect coordinate values (transposed X and Y)
• Two struts had the same number
• There was a missing strut

It would have essentially been impossible to spot these errors without the nose calculator. I created many views of one slice or another from different perspectives to be able to spot what was wrong.