原创 Inamorata prognostication engine design (Part 3)

Pedagogical	=	Educational
Phantasmagorical	=	It's pretty darned fantastic
Inamorata	=	The woman with whom one is in love
Prognostication	=	Predicting the future
Engine	=	Machine

One way to think of this is as a high-tech, Steampunk version of a Magic 8 Ball. The idea is that I will be able to use it to predict whether or not my wife -- Gina The Gorgeous -- will be in a good mood when I next see her and whether or not the radiance of her smile will fall upon me and lighten my life.

 

Actually, when I come to think about this, it dawns on me that I really don’t need a prognostication engine to tell me my future, because I already know the answer to my question (LOL).

 

I gave a presentation about this little beauty at EE Live! 2014. I am happy to say that this presentation was very well attended -- possibly due to the free bacon and beer -- and the audience was very enthusiastic about my project.

 

So, let me bring you up to date with the current state of play. In my previous blog on this topic, which I posted just before I set off for EE Live!, I'd just taken possession of the machined brass panels. These were created for me by my friend, master machinist David Guthrie. David is the General Manager at MaxFab Precision Metal Fabrication & Machining, which is located just down the road from my office.

 

When I returned from EE Live! David presented me with the remaining parts -- a variety of bezels that will be used to highlight the various knobs and switches. In the image below we see all of these pieces on my breakfast table.

 

In the following image we see the bezels sitting on top of their respective panels. The five big holes without bezels are for the analog meters. These don’t need brass bezels because they already have their own black Bakelite equivalents.

 

In the fullness of time -- after I've artificially aged the brass to look like it's circa 1900 -- each of the small holes at either end of the bezels for the toggle and momentary push-button switches will be filled with a mother-of-pearl dot. Behind each of these dots will be one of Adafruit's Flora NeoPixels. Similarly, each of the 16 holes in the round bezels associated with the five potentiometers will contain one of these mother-of-pearl dots. In this case, I'll be using one of Adafruit's NeoPixel rings behind each potentiometer. And, of course, everything is going to be controlled by an Arduino Mega.

 

OMG! While bouncing around the Adafruit website to get the URLs for the links in the previous paragraph, I saw that the little scamps have just introduced Diffused 8mm Through-Hole NeoPixels. If I were a betting man, I'd wager that I'll be finding some use for these little rascals in the not-so-distant future. But we digress...

I dream of having a proper workshop. If I had the money, I'd build something at the bottom of our back garden and equip it with all sorts of woodworking and metalworking tools. It would be wonderful to be able to spread out over multiple worktables and have things like circular saws and suchlike all set up and poised for action.

 

Oh well, I can but dream. In the real world, I have a little corner area in our garage where I store my rolling tool cabinets. Gina is a realtor, which means she works weekends. Thus, as soon as she drives off to work, I leap into action -- I wheel out my rolling tool cabinets -- set up a folding work table -- run an extension cable to power my drills and suchlike -- and start work on whatever project I'm currently playing with.

 

In the case of this past weekend, I decided to construct a jig to hold the brass panels for my Inamorata Prognostication Engine. In the fullness of time, these panels will be mounted in a beautiful wooden radio cabinet circa 1929. The point is that I don’t want to be working in this cabinet while I'm connecting everything together and prototyping things -- instead, I want easy access to the backs of all of the switches and knobs and meters.

 

My first step was to cut up some 3/4" plywood to make a base and two side supports as illustrated in the following image:

 

 

Next, I glued and nailed two 1/2" x 1/2" strips to each of the side supports as illustrated below. The gap between the strips is to accommodate a pressed board mockup of the radio cabinet's lower wooden panel at the bottom, and the larger brass panel at the top. Since the pressed board is a fraction of an inch wider than the brass panel, I used small pieces of pressed board to set the gap.

 

 

The following image shows the jig approaching its final stages. Now, I don’t know if you noticed in the earlier pictures, but the main (upper) brass panel is wider than the secondary (lower) brass panel. My life would have been so much simpler if they were the same width, but the difference is dictated by the way in which the two panels will eventually be housed in the radio cabinet. The problem is that, if left to its own devices, the lower brass panel -- which is to be located behind the pressed board -- would simply fall over.

 

 

I don’t want to go into two much detail here, but my solution is rather cunning. If you look at the image above, you'll see that in front of the pressed board at the bottom there is a 1/2" x 1/2" strip glued and nailed to the baseboard. There's a similar strip behind the pressed board, with an extra gap between the pressed board and the strip to accommodate the lower brass panel.

 

Also in the image above, you can see a bunch of clamps at the top of the pressed board. These are holding a sandwich of three pieces of wood together while the glue dries. It's probably easier to see what's going on using the following diagram, which shows a cross-sectional view (but without the side supports and their associated wooden strips).

 

Remember that the two 1/2" x 1/2" strips at the bottom are attached to the base -- they are not attached to the pressed board front panel, which is free to slide up and down in the grooves between the strips that are attached to the two side supports (again, the side panels and their associated strips are not shown in this image). At the top of the pressed board front panel we see the sandwich of three pieces of wood. These are the pieces that are being held together by the clamps in the previous image.

 

The end result is that I can slide the pressed board front panel up an inch or so, press the lower brass panel against the back, and then slide the pressed board front panel down, thereby locking the brass panel firmly in place. Next, I slide the upper brass panel down into the grooves in the side supports. The end result is as shown below.

 

And here's another shot from a slightly different perspective:

 

I don’t know about you, but I think this is starting to look rather tasty. The next step is to temporarily attach the bezels, along with the buttons, switches, potentiometers, and analog meters, and to then start wiring everything up.

 

At the same time, I'm going to start experimenting with different techniques to age my brass so that it looks as though everything was fabricated more than 100 years ago. I've got a bunch of small brass offcuts to play with. Some of the techniques I've heard about thus far are to use salt and/or vinegar and/or baking in an oven. I've also heard that putting liquid ammonia in the bottom of a plastic container and then suspending the brass in the ensuing vapor can return good results. And someone told me that the Disney Imagineers use cow manure, but I'm not sure where to lay my hands on that (no pun intended).

 

I will of course be reporting further as things progress. In the meantime, I welcome any comments and/or questions and/or suggestions.