I was home today, sick with some sort of a cold. Late this afternoon, around 5PM, I felt like sitting up at the computer for a while and installed software from eMachineShop. I have to muck about in Windows running it, but the software itself is pretty well done.

EMachineShop is CAD software. You are limited pretty much by your imagination, but you can design any piece you need, in just about any material, made with just about any processes. The software analyzes your part(s) and gives you a quote, including shipping, for the parts. Obviously, the more complex (or exotic) the machining process and/or materials, the higher the cost. When you’re happy with it, click “Order” and your design goes to them and in a few weeks (21-25 days for my design) you get your parts at your door.

For my part, I need a 36-1 ignition trigger wheel. There are 4″ wheels available, but the maximum size to fit in my space is 3.2″.

It took a little bit to get the hang of the software. I needed an “array” command like AutoCAD, but I could not find one. It may be there under a different name. In any case, I drew a 3.2″ circle, a 3″ circle and a 2.8″ circle. Then I drew lines from the center of the circle to a point outside the 3.2″ circle, specifying the line’s angle in 5 degree increments. Using the intersection tool, I broke each of these elements into segments where they intersected and basically erased any line that wasn’t a 36-1 wheel. I have removed extra material opposite the missing tooth to keep the wheel balanced. As calculated, this deeper slot should actually be a teeny bit shy of balancing the wheel, meaning I can use a file to remove more material to balance it manually, plus it’s not really diametrically opposed to the missing tooth. Perhaps by the time I’m ready to order the work, I will remove two smaller notches on either side of the opposite tooth. [ed note: Later when the stock ignition rotor was removed, I noted that it’s hardly balanced at all. The two punched holes would probably need to be doubled to even come close to balance. Consequently, I think I worried too much about balance, but *my* trigger wheel is very close to balanced!]

The software lets you play around with which machines and materials to use. I need something ferrous for the sensor to work. Plasma cutting and laser cutting looked the most likely and laser turned out a little cheaper when cutting more than one.

1 laser cut wheel is $197, but 2 is $192 and 3 is $192.82. The price each keeps dropping as you add more units. For example, 10 units are $225, only $28 more than only 1.