A few months ago, Hack A Day featured an ingenious hack called the Reverse Geocache Puzzle by a gentleman named Mikal Hart (please note that “Reverse Geocache Puzzle” is Mikal’s trademark – my unabashed clone of his project will hereafter be known as the Frustromantic Box). As soon as I saw it, I knew I had to build one. It took a lot longer than I thought it would, but I had the finished product ready in time for my wife’s Christmas present. She still hasn’t opened it, so I have to be a little cagey here.
I’ll describe this project in a series of posts. This post – the first – will go over the high-level design of the box.
The goal of the project is to produce a box that is locked from the inside and will only unlock itself at a specific location. The Frustromantic Box actually has two locks (a lid and a drawer) that can be toggled independently. Here’s the parts list:
Woodworking Parts:
- 5′ of cherry 1″x6″ for the sides of the box
- 5′ of cherry 1″x3″ for the lid of the box
- 1/4 sheet (4′x2′) of 1/4″ birch veneer plywood. This is more than necessary, but it was the smallest amount I could buy.
- Small can of Varathane Gel Stain (602 Cherry)
- Small can of Varathane Professional Clear Finish (Clear Gloss 900)
I bought all the above supplies from Windsor Plywood. If you’re a novice woodworker like me, I strongly recommend building a prototype out of pine first. I used a router, a mitre saw, a table saw, a biscuit joiner and a scroll saw to cut the various pieces to size. I used a couple of these speed clamps to assemble the pieces.
Electronics Parts:
- Arduino Duemilanove
- Arduino Protoshield
- Mini Self-Adhesive Breadboard
- HD44780 LCD Display
- Icecube Light Pipe Switch
- Polulu Pushbutton Power Switch LV
- Full Rotation servo
- EM406A GPS Sensor
- Hitec HS-81 servo
- Panasonic PNA4602M IR Receiver
You can tell from the links, I ordered almost all the parts from Sparkfun. Those guys are great. However, the Light Pipe switch was a real pain to use. If I were to do it again I think I’d order this pushbutton switch from Seeedstudio (also a great place) which is the same one that Mikal used in his project. The HS-81 servo I picked up from a local hobby store when I decided to add a locking drawer to the box. The IR Receiver is used to activate the “back door”, I just had it lying around from an earlier project. The full rotation servo is unnecessary and makes the Arduino software a little more complicated than necessary. In hindsight I probably should’ve got this servo instead.
Miscellaneous Parts:
- 1/4″ eyelets (I got a pack of these from Home Depot)
- 1′ threaded pushrod + clevises (also from the local hobby shop)
- 1/4″ dowel (Home Depot)
- Ikea MOLGER toiletry container thingy
- Ikea BJURÖN plant container thingy
- 2′x2′ velvety cloth (I’ve no idea what the proper name for this textile is, I used it to cover the bottom of the box)
- Lee Valley Concealed Lid Hinges (this was a bad idea)
The eyelet holes should be just big enough to accomodate the pushrod, with a little bit of wiggle room. We will transform the Ikea bits into a crude drawer. I recommend against using the concealed lid hinges. My experience with those hinges is, you can either have the lid flush with the top of the box when closed, or you can have the lid open a full 90 degrees. You can’t have both. If I were to do it over again, I’d just use some nice stainless steel hinges and chisel out whatever notches are necessary.
I didn’t take any pictures of the build process, so I’ll show that using some SketchUp models. But here are a few shots of the finished product:
Continue to Part 2: Assembly
Hey, cool! Thanks for sharing.
Mikal
Thank you! It’s an incredible idea, and I couldn’t have done it without TinyGPS and NewSoftSerial.
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How cool… I’d like to see the top and how you locked the box.
Congrats. It looks great.
Thanks! I posted a couple pics of the top and the latches. The top is just birch veneer plywood, the latches are servo-driven like the original design.
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This seems like quote an amazing project. I’d love to do something like this for a loved-ones birthday/christmas.
I noticed on your electronics list you seem to be missing the GPS unit, which I saw in the electronics diagram a few pages over.
If I had to guess I’d put this project total at around $200? Close at least depending on what you already had and tools available.
anyway, great job! thanks for the write-up.
Hi, Jeff,
Whoops, thanks for pointing that out. I’ve updated the parts list. The GPS component is an EM406A. Yeah, I think the total cost was somewhere between $200-$300.
Any arduino compatible boards should work; it doesn’t have to be the Duemilanove. Even the ones based on the Atmel168, like the Diecimila, right?
Also, I’m thinking I will use reverse spring hinges (if I can find a supplier) with a string connected to a stepper motor. This way when access is granted the motor turns, letting the string out and the lid slowly opens on its own.
That’s a good idea about the hinges, Jay, please let me know how it works out.
Yes, any Arduino-compatible board should work. I used up nearly all the digital I/O pins on the Duemilanove, though, so you might want to be careful about that. Altogether I think I used up about 50% of the available program space.
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Thank you so much for sharing. Between your details and Mikal Hart’s I was able to put together a similar box which I titled the “Proposal Box”. Of course I used it to propose to my now soon to be wife. It could not have turned out any better! I’m already thinking about doing this with yet another adventure. Thanks again for sharing your hard work.
Congratulations! Glad to hear everything worked out for you.
Look very nice.
What happens when the battery dies?
I am looking forward to creating this amazing cache container. I am afraid that I may get it started but never be able to finish it.
Thank you all for sharing.
Andrew
Hello,
The link for the Pushbutton switch is not working. Can you post the correct link for it.
Andrew
Really? Both the links (the light pipe switch and the polulu switch) work for me…
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How sensitive is the box/how close to the location do they have to be to unlock the box?
Hi, Troy,
The GPS is sensitive to within a few meters, but the software will unlock the box when it’s within 1km. Part of the reason for that was, the first location was at a spot on a beach that is underwater at high tide.
I have built a box with code based on Russ’s posted code (some calculation changes with Russ’s help) and the box will open down to 50m to 70m. You could probably go down to 10m but it would make the final few tries quite frustrating.
I have found 70-100m is fine.
Hey
first, thanks for the nice tutorial.
can i use something other as the Polulu Pushbutton Power Switch LV?
i didnt find the button in some other shops and only for this one thing a order from spark fun is expensive.
thx
Hmmm… not sure about that. Maybe you could hook something up with a solid state relay? If you figure it out let me know.