The Torus

Hi All,

In week three we will be making the Torus. And a Ferrari!

Theory, Russell:

A Torus is a shape defined by two circles. It has a revolved radius and a ring radius.

The revolved radius is indicated here by the letter 'b" the ring radius is indicated by the letter "a".

In metal shaping the Torus is a shape known as a Reverse Curve. In contrast to the curves of the Bowl, which go in the same direction, in a reverse curve the curves of the sections at 90 degrees go in opposite directions; you can see this clearly in the image by Sinead Martin below ...

  

Sinead Martin in the final stages of planishing her reverse curve.

Imagine your 240mm x 120mm piece of aluminium being divided into three strips along its length. To achieve the reverse curve the long outside edges need to have more area that the inside strip. You can achieve this is two ways, by stretching the outside edges or shrinking the inside strip. Daniel will demonstrate a technique for shrinking the inside strip and Gabe will demonstrate a technique for stretching the outside edges. 

If you are ambitious you can also turn the outside edges back around to make the shape look even more like a Torus, seen here in an image by Sonia Cunningham:

    Sonia Cunningham's reverse curve with the outside edges rolled over. 

Option 1, Shrinking the center strip: Daniel

Daniel follows the method described by Wray Schelin which uses a depression carved into the radius of a stump to shrink the center. You create a fold around the outside which traps the aluminium as you work back towards the center. This works like a three dimensional tuck (as opposed to the two dimensional tuck of the Bowl). The metal doesn't like to cross over fold or crease around the outside edge because the aluminium sheet is stronger there because of the fold/crease.  

 

Option 2, Stretching the outside edges: Gabe

In this option Gabe will use the English Wheel to stretch the outside edges. It's a bit slower, but quieter and more controlled. This technique is good for making subtle curves.

 

Option 3, Stretching the outside edge using the Shrinker/Stretcher Tool. 

We won't demonstrate this technique, but we do have a Shrinker/Stretcher in the workshop so I thought you might like to see it in action. This method leaves marks in the aluminium and can tear the aluminium easily. Having said that, in some situations (turning short flanges for example) it is your best option. See Lazze demonstrate this below.




Making a model Ferrari, using Slicer: Martin.

This is how you'll make the template for the motorcycle fuel tank in the second half of the course. You can download a model of the Ferrari 250gto yourself and experiment with different ways of configuring the software to create a template for shaping the aluminium panels. It's an incredibly powerful piece of software and very useful for quickly prototyping your digital designs; see the demonstration below to see it in action:



You can download Slicer for free through the Autodesk student portal. 

I would also highly recommend Fusion360 ... it's a modeling software that is easy to learn, fully parametric and links directly to manufacturing through 3d printing, CNC machining and laser cutting. It'll take your digital modeling to a level beyond Sketchup!

https://www.autodesk.com/education/free-software/featured

Enjoy!

Russell