I'm searching for the best housing for a re-imagination of the thermal fishing bob.
I'd like to replace the Country Time Lemonade container with something sleeker and more functional. This may involve fabrication in the shop or collaborating with a manufacturer to get custom parts made remotely.
Basic parameters of the new object:
- spherical
- floats
- white opaque
- ~5" diameter
- can be opened to insert electronics
- can be water sealed (additional step may be necessary)
We (thanks OBMG!) brainstormed a number of existing objects that fit at least some of these parameters:
- ping pong balls
- beach ball
- easter eggs
- cupcake containers
- Russian nesting dolls
- wiffle balls
- PVC caps
- balloons
- "shade balls" (see here and here)
This suggested the following processes, some of which can be done on site at MIT:
- Vacuum forming (youtube video)
- Blow molding (youtube video)
- Hypnotic video about making ping pong balls here
I'm also contacting manufacturers to see if this can be custom made offsite:
An Alibaba search is next on the list...I've had good luck with manufactures found there in the past!
Thanks everyone for the great suggestions in the comments and elsewhere! I put together a summary of sources I've found since the original post:
Current winner: acrylic ornaments size 1 size 2 size 3
Other options fishing bobbers (@warren)
towfish (@mathew)
beer ball/party ball (@DavidMack @liz) (hard to find! some forums suggested these might not be sold now)
LED balls version 1 version 2 version 3
ice cube trays to use in molding & casting parts version 1 version 2
Brainstorming points of interest:
- rubber wine glasses
- rubber balls with a slit hole in them
I've also put together a list of Alibaba manufacturers to contact.
Re: electronics (@warren)
Don (@donblair) and I have been working together base regularly on this--our long term plan is to use this as one of the first breakout boards for the Riffle. For this round of prototyping it's been easier to get things going on Arduinos (Riffles are still a time intensive board to put together). We did recently transfer to the 3.3V Arduino Pro Mini since it's a closer cousin to the Riffle than the Uno--so hopefully it'll be a seamless transfer to the Riffle when it's good to go. Data logging and GPS are other things we're adding as it'd be nice to complement the real time display with logged data that we can dig into a bit.
Also, for this particular implementation, the larger size is an intentional design choice as it is better for visibility from a distance, especially given the number we're initially planning to put in a chain (~5). It is interesting to thing about another version that's smaller--more of a point source net of data--as a potential next step or alternative direction.
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first thing that comes to mind is a beer ball--do they even make those anymore?
also look at "floating pool lights" Maybe you can get them wholesale somewhere.
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Hi, I think the enclosure could be a lot smaller, if you build on some of the other work folks have done on thermal fishing bob designs, for example, the 555-based analog design work, which'd be super tiny, or the Digispark based version I posted on @kgrevera's post a while back:
http://publiclab.org/notes/kgrevera/07-06-2015/cape-cod-thermal-fishing-bob-field-test#c12101
A TinyDuino could also run off a coin cell battery, making it even smaller.
The original idea for the TFB was to have it fit inside an actual fishing bob:
That way, it can be cast from the shore and dragged back slowly for a thermal image. This also means that you need to be measuring only one temperature at a time, because the color indicates a single temperature at a single depth. This simplifies the design dramatically, making it much easier to construct. A single thermistor and a single RGB LED plugged into a DigiSpark or a TinyDuino has only 4 parts:
= <$26
Instead of adding complexity to the device, we could keep construction time and cost very low, and cover a large area quickly by casting it with a fishing rod. To measure at depth, you can put the thermistor deeper with a fishing weight, just like you'd do with a hook.
For a container, I think an old film capsule could work, since it'd seal nicely (you could use plenty of silicone glue or hot glue to seal the thermistor through a hole cut in the bottom) or you could go the @donblair route and use a tiny Dasani water bottle. Don's done a lot of work to get a good seal on a bottle cap, and is also working with thermistors.
Scratching the outside of the bottle with fine sandpaper would also help diffuse the light to make it easier to see.
What do you think?
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