prototyping process
Making this project was easy. In fact, you can enjoy this kind of success by following my simple 28 step process:
Haha. 
Now that I’ve gone through the process once, I think I can probably eliminate a lot of these steps next time. In the grand scheme of things, this project went surprisingly smoothly. I think I’ll need to credit the copious amount of time I spend going from Sketchup to illustrator then back to sketchup.
here was the original prototype sketch:
This is the concept sketch for one column of the digital I/O pins:
Why did I choose these components?
well, I sourced a lot of my parts in person from Halted. Although I did spend a lot of time getting to know the Mouser catalog… AND, a paper-version of this monster did just show up on my doorstep today. I did source the 2 terminal screw headers from there so smartly they sent me their whole catalog in dead-tree version… smart. I’ll likely go through their electromechanical section with a fine tooth comb to locate acceptable replacement parts… but for this initial version, the decisions were based on what I could put my hands on and actually try out the feel of the controls.
- slide switches: these had the nicest control size to price ratio that felt comfortable for having to buy this many of them for the project. They were surplus, so if I had to locate them again I may have problems. Or I may have to get really good at reading and interpreting datasheets.
- SPDT switches: I liked the size of these controls. There isn’t a whole lot of variety in this department for the kind of control I wanted. It seems to go from teeny tiny little switches to small, to freakishly giant, to ridiculous. So I went with the small ones.
- rotary pots: these are kind of standard issue pots.. The thing I learned was that there are two kinds out in the market. Linear taper and logarithmic taper styles. The logarithmic style are sometimes called “Audio taper”… and I figured if I needed to affect the curve of data coming from a control, I could easily do that after the data is captured from a linear taper source.
- breadboard: My mom bought this for my science project my brother and I did for my 8th grade science class. *cough*mostly him*cough* … back in 1988. So I had it laying around. I tried 4 different stores to locate a new crisp clear known-good breadboard the same size and had no luck. I was trying to avoid having to order something online, but it looks like I won’t be able to avoid it if I want to replace the current one.
After acquiring most of my parts and measuring them all, I went to Illustrator to lay out the panel with the intention of taking the design to TechShop and cutting the panel on the laser cutter… I ended up cutting it out of thin plywood with a scroll saw instead but the process was still extremely helpful. Here’s what the Illustrator layout looked like (before discovering some problems with the way I have the orientation key holes laid out for the rotary potentiometers, and of course the corner stand-off fiasco…
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Here’s the same illustrator layout taken back to sketchup for a more official pre-visualization.
I actually discovered some issues with the way I was going to handle the slide potentiometers and came up with a fix in sketchup to visually design something nicer. Then I went back to illustrator and applied the changes I made in sketchup to the layout. Check out the sliders between these two versions:
Even after I cut the panel’s holes and populated the componentry to the panel, I discovered things that I never would have been able to catch until it was too late. So, that’s what makes a good reason for version 2.0.
Ok, so once I had my panel mostly done, I needed to build a box to hold the panels. Sketchup is really great at making all of the hard joinery decisions really obvious, and then makes it easy to pull exacting measurments without having to second guess yourself. This box turned out *great*. Possibly the best box I’ve ever made, and relatively stress free because I knew my measurements would be good.
and while this photo isn’t the final product, I think you’ll agree that this method can produce very close approximations of reality.
