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, 12 March 2012

Slicing and Dicing Oxenham style!

Today I headed out to our styrofoam supplier to pick up all our sheets that we will be cutting the shark dispenser out of.  I actually had to do 2 runs, as I couldn't fit all 26 sheets into my Caravan at once. We ordered 3"- type 2 styrofoam. I went with type 2 for this job because it's going to get approx. 1/4" of urethane hardcoat sprayed all over it, and we may need hog out additional space inside to fit the dispenser unit it houses. Normally I would use the denser type 3, but that would just be adding useless weight considering the coating. By the time the order was ready, and I got back to the shop, it was already 5pm and I still had to cut out a small beer tap handle I modeled for a customer over the weekend. So the foam will fly first thing tomorrow. I did enjoy the time I spent last week, and weekend, working only in the computer, but the craving to make something real was gnawing away heavily by Sunday morning!
One of the most time consuming computer jobs was slicing the shark up into machinable slices. We have decent gantry clearance on our Techno cnc, but that's only one of the considerations when choosing the slice thickness. We are fairly limited on time for this job (story of my life!), so I'm going to use a modified 1/2" drill bit as a cutter. This will allow room for the cutter to rapid move above the material, as well as cut through the whole 3" in one pass, removing the time required for a roughing pass.
 Just a reminder of what the finished job will look like. The opening in the chest is for people to be able to see what's happening inside the dispenser. I do believe he gets a speaker installed into the roof of his mouth as well.

After most of Saturday, this is the shark exploded into the 3" sections, ready for bringing into ASPIRE!
As Aspire will fill in any undercuts when importing the pieces, it was very important to pay attention to how I was splitting it up. Some pieces will be split further in Aspire, and lots will have to be double sided machined to get all the detail.

This is an example of the arms and fins that I let Aspire slice up. One of the most usefull toolsets in Aspire, for this kind of work, is the "fit vectors to bitmap" feature. It  allows me to quickly, and very accurately, apply machining boundaries to the top and bottom of each piece, without killing myself by hand-drawing them in. Doing it this way drastically reduces machining times by having the cutter only cut the critical geometry of the part, not the whole thing. Anytime I can reduce unnecessary cutter movement, I reduce the time each part is on the machine.

On another note, I have been invited to teach some of my skills in Indiana in June. I am very excited!!! A fellow forum member, and Aspire user, by the name of Robert Jones will be holding a "sign camp" at his place and asked if I would be interested in showing some of our tricks methods. This is very flattering to say the least!
One of the neat things is that everyone who signed up for this camp will be receiving a 24"X24" HDU sign. I will be demonstrating some of the ways we finish our signs, and they will get to try out the techniques on their own custom pieces. So on Sunday I was able to finish up a design for Diane and Ernie Balch, They sent me some artwork, and mentioned they like to fish. So based on the information they sent, as well as knowing the finishing we will be exploring, I came up with this design that Robert will be cutting on his router for them.
 Simple and fun, I like it!