The Tray

Hi All,

You'll be working in pairs to create the Tray in today's class. 

Theory, Russell:

The Tray is an open box shaped form which has radiused corners so that the edges can be turned up continuously around its whole perimeter.

You can see the development of the tray in Sonia Cunningham's work from last year here.   

The main technique we will be using is called Hammer forming. In this case we will be hammer forming around a male buck.  

In the video below you can see a very heavy steel hammer forming buck. It consists of two parts that are clamped together. The bottom one is your goal shape and the top one follows that shape but is usually a bit smaller. The purpose of the top shape is to clamp the material in place so it doesn't move when you are striking it or lift up in the opposite direction to your blows so that the edge is less sharply defined.

As the demonstrator below works along the edge you can see the tucks that form on the outside radius (where the aluminium is shrinking). It's almost impossible to see the stretching that is happening on the inside radius; but it is happening and his advice regarding starting from the top and working down to avoid splitting the aluminium is evidence for the stretch.


  
Our hammer forming buck will be made from scrap timber that you can find in the workshop. While not as strong as a steel buck timber is usually fine when forming soft aluminium or when you only have a few parts to make.

Follow these steps:

1. Find a student from a different discipline, or different year in your discipline, or someone who you haven't met before.

2. Jointly determine the length and width of your trays (we recommend a maximum dimension of 220mm in the long dimension).

3. Jointly determine the corner radius of your trays. This will be driven by the size of the dolly you can find or make.

Note: there are a collection of steel disks/cylinders in the metal workshop that you could use as dolly's, but you might make your own out of timber. Keep in mind larger radius's are easier to form. 

4. Individually determine how far the edges turn up on your tray. Keep in mind the further the edge turns up the harder it is to form the radius's on the corners. Turn the edges up at 90 degrees from the base.

5. Once finished place your trays so that the open edges on each tray touch ... they should match perfectly. Use still images and video captures to demonstrate your skills.

Marking Out, Martin:

We have provided a template to laser cut that you can use to help mark out your tray and your bucks (the zip file contains an Adobe Illustrator file and an AutoCAD file, both are the same).

See if you can figure out our recommended dimensions by analyzing the completed template.

Mark your tray out on the aluminium. We recommend you cut your aluminum sheet to the outside size on the guillotine and trim the corners with the aviation snips. Debur the edges. Use a engineers square and scribe to mark the lines in the aluminium. 

Here is a suggested procedure:

Cutting and shaping the hammer forming buck, Gabe:

Mark out some pieces of flat timber with a pencil or pen to use as your hammer forming buck. Cut with the band saw or ask for assistance with the new table saw. Use the sanders to clean up your radiused edges.

You could also create some implements for hammering the edges down. You hold the implement between the hammer and the aluminium like a chisel. Their purpose is twofold; to enable getting into tight corners and turning any lump of material into a hammer (with a soft, un-marking face). The tools made from timber and nylon to the bottom left of the image below are what we mean. The two wavy shapes are hammerforms and you'll recognize the mallets.

Folding the edges and Turning the Radius, Daniel:

Clamp the aluminium between your two pieces of timber and slowly work your way around the perimeter until the edges turn down at 90 degrees to the base. Follow Daniel's advice and the advice from the video above to avoid creases at the corners.