Prototyping: Part 5 – Design & Fabrication

2011 June 6
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Photos are courtesy of Jamie Mulhern (verticals) and Acme Metal Works.

This week, we continued with the assembly of the prototype and did some plasma cutting to separate the roasting bowl from the upper ring that will hold the return vanes. By the end of the week, we were able to run the bowl to make sure everything is working properly so far. All of the work was done at Acme Metal Works in Gilbert, AZ.

First, the bowl and shaft assembly, along with the drive gear were installed into the base table.

The control panel for the motor was mounted on the edge of the base table.

At this point, the bowl is ready to be plasma cut.

Tom Eckholdt begins the plasma cut while a co-worker slowly rotates the bowl. The idea is to make a cut that is at exactly the same point relative to the table surface.

As the plasma cutting continues, the upper ring begins to lift off.

After finishing the cut, the upper ring is set aside for further assembly.

The bowl is now at its final height. Tom checks the “run out”, which is a measure of the out-of-roundness in the bowl. Due to stresses being relieved during plasma cutting, the bowl warps slightly and needs to be carefully bent back into alignment.

Next, it is time for a test run to make sure that the bowl is balanced and the shaft and bearings are aligned properly.

The bowl is run up to maximum speed of 200 RPM and all is well. There are no vibrations and it runs smoothly. It also powerfully ejects any object dropped into its center: proving that centrifugal force is very much alive!

The bowl is cleaned and surfaced and the center cone fit is checked.

Meanwhile, the return vane strips have been delivered from the water jetting subcontractor. The vanes will ultimately be fit into the upper ring.

Next week, the upper ring will be installed and the roaster prototype delivered to our test area for initial testing.

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One Response
  1. Keith P permalink
    June 13, 2011

    I hope that you are feeling much better this week. I will have to catch a glimpse of the roaster at a future U-Pick date (if not another time).

    Have a great week!
    ~Keith

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