In an earlier post I mentioned that I’d used a tube of silicone to put a drop of silicone on each solenoid, to reduce the loud ‘clank’ when the solenoid strikes the chime. I found out that a drop of silicone is way too much: the chimes hardly sounded at all.
I then found these fabulous 21-gauge glue syringes on Amazon. They’re perfect for painting just the right amount of silicone on the tip of the solenoid. They’re easy to use: pop the syringe open, squeeze a little (very little) silicone out of the tube into the syringe, touch the tip of the syringe ‘needle’ (really a thin metal tube) to the solenoid tip, then gently squeeze the syringe plunger as you paint the silicone onto the solenoid tip.
The photo below shows the result: a pad of silicone that’s about 1/2 the thickness of the drop shown above. I still have to experiment / adjust a bit: I thought I painted all the solenoids with about the same amount of silicone, but the chimes sound very different from each other. I suspect that I just have to be more careful about painting exactly the same amount of silicone on each solenoid.
Since my last post about the glockenspiel, I’ve been taking a vacation from my vacation (aka working). Today I turned back to the glockenspiel and wired up the first of the 5 lighted switches.
The hardware is lighted buttons from Sparkfun in various colors, some 4-wire phone cable I bought years ago, and 4-conductor 0.1″ connectors. The heat-shrink tubing keeps the 5 pins of the button from shorting to each other. Two wires run the LED, and the other three make up the button (common, normally open, and the unused normally closed).
I had a little trouble reading the switch: whatever I did, the output was close to ground. After much experimentation, I realized that the pin I was using (pin 52) is used on the Arduino Mega 2560 for part of the SPI bus. Once I moved the input to an unused pin, it worked like a charm, with the internal pull-up resistor to keep the parts count nicely low.
In my previous post, I started putting the glockenspiel case together. Now I’ve bolted the glockenspiel harp and circuit boards into the base of the box, and temporarily mounted the handles and buttons. I still need to wire up the buttons.
In other news, I’ve tried out various ways of damping the initial, loud “clank” when a solenoid strikes a chime. A piece of scotch tape on the top of the solenoid had no effect at all; a dab of silicone (which someone else suggested) can make just the right sound, but I’m a little puzzled about how to repeatably put just the right amount of silicone on each solenoid.
In my next post I reflect on how Design Thinking could have improved the project.
After a pile of routing I’m now nailing and gluing the Robotic Glockenspiel box together. Since this is a first prototype (the flat chime harp is too large to be practical), I’ve made the box sides from 3/4″ x 6″ “white wood” (fir or pine) instead of hardwoods, and made no attempt to conceal the nails.
The base and top of the box are 1/2″ plywood with a nice veneer; the sides are fir/pine. The base is held in place by 1/2″ wide and 3/8″ deep dado joints in each side; the ends are connected via rabbet joints (which you can see in the photo). I’ve routed holes in the front for the 5 buttons that will control the glockenspiel, and scroll-sawn holes in the back to plug in power and usb cables. I also used a flush trim router bit to make all the sides the same height (for some reason one of the boards I bought was about 1/16″ wider than the other).
I’d hoped to plug/unplug the SD card from the back, but found the thickness of the box walls would require a huge hole to get to the SD card. So instead I cut a small hole, then decided to plug/unplug the SD card from the inside.
I plan to connect the lid via a 30″ cabinet hinge from Lowes. I’ve routed out an indentation in the back of the box so the hinge will be flush with the top of the box.
Since this weekend is the end of my end-of-year vacation, progress on the glockenspiel will likely be a lot slower from now on.
The next step is to drill all the mounting holes, put a clear finish on the box, then mount the chimes and circuit inside the box. I plan to figure out the lid later.
In my previous post, the robotic glockenspiel played its first tune. This post is an update on transcribing more tunes.
I’ve been busily transcribing public domain Christmas carols from “The Oxford Book of Carols” and other sources of public domain carols, so the glockenspiel has more material to play. All the carols are checked into the SD folder of the Robotic Glockenspiel Git repository, and are part of that open source project.
In other news, I bought this edge guide for my router, so now I can cut the grooves that will hold the base of the glockenspiel. Next I need to learn how to make rabbet joints, so I can put the glockenspiel box together.
My next post is about crafting the cabinet for the glockenspiel.
Et proiectus est talpa – "and the mole was cast out"