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.

Wednesday, 21 November 2012

Advance to Boardwalk!

First up on the Monopoly build is the iron! It may be because it looked the easiest, I don't really know.
This will be a straight build, with no 3d work on our Techno cnc.
I was able to export the .stl mesh data from Hexagon to Corel. I'll use this data to pull sizes and angles from.
It turns out that at this scale, the irons handle is so close to 5/8" diameter, that I could use a piece of acrylic rod we had. I laid out the size and angles for the handle on a piece of melamine, then using a torch, was able to quickly heat bend the acrylic rod to the needed shape.
They have requested that we make the base of the iron around twice as thick as the cad file, as to read better on camera. I made the decision to cut the handle down a little to compensate for it.
For the gripping portion of the handle, I had a piece of pvc pipe that was SO close to the size, I decided to use it. I split the tube down the middle, hoping it would close in a little, like EVERY other pvc pipe seems to do, but no luck! It held its size steadfastly. I ended up gently heating it, to open it up enough to fit over the rod. While it was still warm, I closed it back together, and glued the seam.
I pulled the profile shape of the iron base out of the drawing, and toolpathed it in Aspire for cnc-ing. I cut this from 3/4" pvc. I took the handle angles, and set up the drill press. I punched the holes in about 1/8", so the handle has a secure mounting method.
Once the handle was securely glued in, I drilled through the bottom of the 3/4" pvc, so I could screw the handle in as well. An on-set iron malfunction is no fun for anyone. The final piece was a plate of 1/4" pvc glued to the bottom of the iron to cover the screws, and get to our 1" thickness goal.

The iron will sit clamped overnight, while we moved on to the other elements.
Next on the list was the hat. I figured this was the most amount of work, and wanted to get started on it right away.
The stl file mesh was pretty dense on the hat. In fact, it was so dense, using it for anything but a size reference was impossible! I re-drew the form on the left at a way lower polygon count, in a usable mesh for this build process. I never had any intention of 3d machining the hat anyway. . I was hoping, in the beginning, to just wrap some styrene around a form. But it became very evident that the top portion of the hat actually has a 1.5 degree draft. Darn! I was able to un-wrap my new mesh in our other software package, which would give me the flattened shape, allowing for the draft angle.
The left side is my imported mesh, and on the right is the unwrapped template. I'll cut this from .060" styrene sheet.

 I'm also cutting a slightly larger one to wrap around the first one. This will allow me to overlap the seams, and make the wall thickness 1/8" thick. The double wrapping will also help the styrene hold its shape securely.
I cut the top plate for the hat from 1/4" styrene, leaving a rabbet for my double wrapped piece to securely glue to.
While the upper portion was setting up, I cut the brim of the hat out of 3/4" pvc.
The brim of the hat has a definitive curve to it. I decided that the best way to tackle this would be to make a wood cradle, with the same curve as the cad file of the brim of the hat, and drape form the pvc. I havent actually drape formed 3/4" pvc, but I figured the process would be the same as other materials, but the heating time would vary. I did this at home, as I only have a small oven at the shop.
Well, it turns out that 12 minutes at 375 degrees is the perfect time and temp. The hot pvc draped beautifully into the wooden form. Unfortunately, the house now smells like cheap beach-balls. Glad I didn't throw it in the oven with the chicken Jody was making for dinner!

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