The mighty Jabba asks why he must pay fifty thousand.
Because he's holding a thermal detonator!
With Star Wars day fast approaching I felt it was only appropriate that my next project was a Star Wars one. I figured that the thermal detonator was the way to go.
There are quite a few examples of replica thermal detonators out there as well as the official Lucasfilm licensed master replicas props, but I've not come across any instructables for one yet, so I've happily obliged.
I used a 3d model created by Oubliette as the basis for my detonator, it's a good quality model that prints well and assembles nicely, the model is available on Thingiverse, also be sure to check out Oubliette's website.
This instructable covers the 3d printing of the prop, the painting (including a handy weathering technique) and the electronics to generate the lights and sounds of the prop.
May the 4th be with you
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Step 1: The 3d Printed Parts
I printed mine using the following settings on a XYZ DaVinci 1.0:
- Infill: 90%
- Layer height: 0.1
- Supports: Yes medium density
- Speed: Standard
- Shells: Normal
Once you've printed the pieces you'll want to check everything fits, if you find things are a little tight you may want to sand the areas where the different parts meet. Remember that if things are tight now, they'll be even tighter once you've put a few coats of paint on.
Step 2: Painting and Weathering
To paint the Thermal Detonator and apply the weathering effect, you'll need the following colours:
- Metallic Brass / Gold
- Brilliant Metallic Silver
- Matt Black
To create the weathering effect, you'll need the following additional items:
- Small paint brush for applying water
- Clean and dry toothbrush
Lightly sand the 3d printed parts with a fine sandpaper (P120) to smooth prior to painting, taking care to remove any dust with a tack cloth. I then primed the pieces using an all surface primer and left to dry for a few hours. The top slide switch grip piece is then painted in the matt black.
First Coat of Colour and Paint Weathering
To create the weathering effect we will first paint the main detonator parts using what will be the rust / corrosion colour. Spray the top section, bottom section and main slider piece in the gold / brass. I did a coat of the metallic brass, then after allowing a few hours to dry I followed this up with a coat of metallic gold, immediately followed by another coat of the brass. You will want to want to allow this 24 hours to dry as the paint needs to be 100% dry before the next stage.
The weathering effect will be achieved by using the salt and water. Using a paint brush apply water to the areas that you want to have signs of corrosion, you'll want to focus on areas where moisture and dirt would naturally collect (such as in and around grooves).
Take the salt and sprinkle it over the thermal detonator, you'll find that the salt will stick to the wet spots and begin to crystallise. Once you've covered the wet areas in salt you'll want to leave it for at least an hour to let the salt dry thoroughly.
Once dry you can gently blow off the loose bits of salt, you can then spray paint the rest of the thermal detonator in the final colour. I opted to use a brilliant metallic silver. Allow another 24 hours for the paint to thoroughly dry.
Now comes the fun part, using the toothbrush you can remove the crystallised salt to reveal the corrosion, this should leave you with a fairly good weathering effect. Test fit the assembly again, you'll want to make sure the paint hasn't stopped things from fitting together nicely.
Step 3: Intro to the Electronics
Using lighting and sound on a prop really adds that extra dimension and brings things to life, the thermal detonator is no exception.
To re-create the light effects we will be utilising the following items:
- 1x 08M2 PICAXE Microcontroller
- 3x 3mm Yellow LED's 2.1v forward voltage
- 1x Red LED 2.1v forward voltage
- 1x 10Ω Resistor
- 4x 120Ω Resistors
- 1x 100nf Capacitor
- 1x Roller-switch
To re-create the sound effects we will be utilising the following items:
- Adafruit FX Mini Sound Board
- Adafruit 2.8W Class D Audio Amp
- Visaton K50 8Ω Speaker I'd recommend using a small profile speaker to save space
Alternatively Adafruit also have a combined sound board and amp, though stock is limited as I believe the item may have been discontinued.
The whole thing is powered using a 4.5v battery source, I used 3x AAA batteries for testing purposes and these are replaced with 3x N batteries in the final assembly to save space.
Experimental: I've included some PCB design files for the circuit. One design is intended to use serial communication with the soundboard to trigger sounds, the other uses the GPIO based triggers. It also includes a tilt switch and a DIP switch to give more functionality. More info to follow once I get the chance to build and test...
Step 4: Lighting and Sounds
The circuit is assembled as per the schematic provided. The on/off switching is achieved using the roller switch. When the top slider is slid back to reveal the red LED, the roller switch opens. This closes the circuit, activating the lights and triggering the sounds.
You'll find that the batteries are one of the more troublesome aspects of the build. You'll need something small enough to actually fit inside the Detonator enclsoure, but also large enough to operate the electronics for a suitable length of time.
AA and AAA batteries are too large to fit inside the enclosure, so I opted for the smaller N batteries. I recommend using a battery holder like the one shown in the photos as it will make changing flat batteries easier. But as I was in a hurry, I soldered my wires directly to the batteries.
Flashing Light Sequence and the PICAXE
The yellow flashing lights on the front of the detonator are designed to replicate the pattern and timing of the movie prop. It only appears on-screen in ROTJ for a few seconds so the start of the light pattern is replicated from the movie scenes, the rest of the pattern is taken from the Master Replicas prop. This light sequence is achieved by using a PICAXE microcontroller, the code I used to program the chip is provided below. I happened to have a spare 18 pin PICAXE to hand so I used that in my build, but to save space I'd recommend you use an 8 pin chip instead. The code below is intended for a PICAXE-08M2 wired as indicated by the circuit diagram.
Main: high c.0 low c.1 low c.2 pause 2000 high c.0 high c.1 low c.2 pause 2000 high c.0 low c.1 high c.2 pause 2000 low c.0 high c.1 high c.2 pause 2000 low c.0 high c.1 low c.2 pause 2000 low c.0 low c.1 high c.2 pause 2000 high c.0 high c.1 low c.2 pause 2000 low c.0 high c.1 high c.2 pause 2000 goto main
The Adafruit soundboard is surprisingly easy to program. Triggers are set by simply naming the audio file, using a file name format that corresponds to the relevant trigger switch. For more information follow the tutorial on Adafruit. I've only utilised the main detonator sound effect, but it is also possible to add additional effects (i.e. detonator explosion when the prop is shaken) through the addition of tilt switches etc.
As an alternative to the adafruit sound board you could also use a PlecterLabs board that's pre-loaded with a Thermal Detonator sound font that includes various other effects and features.
The most complicated part of final assembly is actually getting everything to fit, be as conservative as possible with cable lengths when soldering everything together, you want to minimise unnecessary usage of space as it gets very tight in there! You'll see fromt he photos that I wasn't particularly neat and my strip/vero board is quite large, but even so everything fits.
I placed the components into my detonator enclosure in the following order:
- Amp at the bottom - it is the narrowest so it can sit nearer the base of the curve
- Soundboard next
- Then the custom built circuit - as it is the largest
- The batteries next - all of these should sit just around the height of the three yellow LEDs
- The speaker goes next - you'll see that my speaker is actually quite chunky, a smaller one would fit even better
This should conclude your build, I hope you enjoyed the Instructable.
Note: that I have not included the thermal detonator sound effect audio file as part of this instructable as I am unsure of the copyright status. I believe it was taken from a Master Replicas thermal detonator prop that was created under license from Lucasfilm so I am not able to re-distribute it openly :( If you turn to Google you should find some sound effects you can use.