When I lent my services to a collegue who was working on a film about 12 years ago, I was introduced to the world of cnc. I remember watching this huge machining centre milling out a slab of mdf and turning it into a fantastic set of gears. I knew that it would have taken me hours to achieve the same thing with traditional power tools. I decided then that I would invest in a cnc router for my own business Oxenham Design. At that time I could turn on a computer, but even to check email seemed like a crazy set of operations. I persevered and learned every piece of relevant software I could get my hands on. I am now fortunate enough to be using Vectric's ASPIRE software, and Techno cnc routers, which has helped us to create some amazing projects, both in part, or in full. I thought that this blog would be a great place to share "behind the scenes" adventures with the software, materials and equipment we use, as well as the projects we build.

Monday, 26 September 2011

The money pile grows!

On Sunday, we de-molded the small pile of change we made on Saturday. It came out really good actually. Because the coins were hot glued together, and the undercuts were filled with clay, I was to scared to move the mold to the vacuum chamber for de-gassing in fear I might open up a seam in the original and have coins get trapped in the liquid rubber. So we just left it on its own to de-gas. I was anticipating a few air bubbles around some of the edges, but there were none. Everyone gets lucky sometimes! After that Jody moved onto casting 15 piles of coins from this mold. The next step was to lay all 15 piles out, glue them to a backer board and fill all those new undercuts so the new rubber wouldn't creep where I didn't want it. We were able to de-mold this new rubber today at around noon. I could tell it should have been left a bit longer as it didn't want to release all that easily, but I needed a volume measurement to see how much resin we actually needed as opposed to what the math led us to believe. I was pretty close at 5.5 cups, but the actual volume was 5. This means we would order a 5 gallon kit, which is actually 5 gallons of part A, and 5 gallons of part B, for a total of 10 gallons. And a little left over. It's handy stuff to have around.

So with Jody out picking the resin up, I had to pickup the materials for the coin mound structure. I was able to break down some of the parts in Aspire for a better sheet yield, so I got all the parts onto 2 sheets of 5/8" plywood.

When I first got notified about this job, I modeled a quick computer render of what the piles dimensions would be. After I had the final model sizes in the computer, I spent Sunday evening sculpting the computer model into a more shapely lump.
Once I was happy with the lump, I added a flange to the base for when I slice it, this will give me a flat plane on which to lie everything in the computer.

Next I sliced the file into polylines which will become the ouline shapes of the ribs I will cut on our Techno cnc.

Once the ribs and back of the model were generated, I exported these as DXF's into Aspire, and added a few lines to make the final ribs for cutting.

 I also laid out a half circle arc for the front of the lump, and cut in pockets so the ribs would slot into the half circle ring and the back. It took about 40 minutes to cut both sheets up, and about 40 minutes to assemble it all.

 First thing tomorrow I will cover this lump in wire lathe, and we can start to get the coin sheets attached. I am really hoping by the end of day the whole mound will be silver. Lets keep our fingers crossed!

On a quick note, each small pile contained $15.25 worth of coins. Each large sheet was made from 15 small piles plus an additional $4 in filler coins. We will use around 20 large sheets totaling a real coin total of  $4655.00 worth of quarters and dollar coins!!!

No comments:

Post a Comment