One of the worst things about sewing is finding out that your bobbin — that’s the smaller spool that works together with the needle and the larger spool to make a complete stitch — ran out of thread several stitches ago. If you’re lucky, the machine has a viewing window on the bobbin so you can easily tell when it’s getting dangerously close to running out, but many machines (ours included) must be taken halfway apart and the bobbin removed before it can be checked.

Having spare bobbins ready to go is definitely the answer. We would venture to guess that most (if not all) machines have a built-in bobbin winder, but using them involves de-threading the machine and setting it up to wind bobbins instead of sew. If you have a whole lot of sewing to do and can afford it, an automatic bobbin winder is a godsend. If you’re [Mr. Innovative], you build one yourself out of acrylic, aluminium, and Arduinos.

Here’s how it works: load up the clever little acrylic slide with up to twelve empty bobbins, then dial in the speed percentage and press the start button. The bobbins load one at a time onto a drill chuck that’s on the output shaft of a beefy 775 DC motor. The motor spins ridiculously fast, loading up the bobbin in a few seconds. Then the bobbin falls down a ramp and into a rack, and the thread is severed by a piece of nichrome wire.

An important part of winding bobbins is making sure the thread stays in place at the start of the wind. We love the way [Mr. Innovative] handled this part of the problem — a little foam doughnut around a bearing holds the thread in place just long enough to get the winding started. The schematic, BOM, and CAD files are available if you’d like to make one of these amazing machines for yourself. In the meantime, check out the demo/build video after the break.

Still not convinced that sewing is cool enough to learn? Our own [Jenny List] may be able to convert you. If that doesn’t get you, you might like to know that some sewing machines are hackable — this old girl has a second life as a computerized embroidery machine. If those don’t do it, consider that sewing machines can give you a second life, too.

Thanks for the tip, [Baldpower]!

[Sigurd] manage to obtain an old vending machine from his dorm. The only problem was that the micocontroller on the main board was broken. He and his friend decided they could most likely get the machine back into working order, but they also knew they could probably give it a few upgrades.

This system uses two Arduino Pro Minis and an Electric Imp to cram in all of the new features. One Arduino is connected to the machine’s original main board. The Arduino interfaces with some of the shift registers, relays, and voltage regulators. This microcontroller also lights up the buttons on the machine as long as that particular beverage is not empty. It controls the seven segment LED display, as well as reading the coin validator.

The team had to reverse engineer the original coin validator in order to figure out how the machine detected and counted the coins. Once they figured out how to read the state of the coins, they also built a custom driver board to drive the solenoids.

A second Arduino is used to read NFC and RFID cards using a Mifare RC522 reader. The system uses its own credit system, so a user can be issued a card with a certain amount of pre-paid credit. It will then deduct credit appropriately once a beverage is vended. The two Arduinos communicate via Serial.

The team also wanted this machine to have the ability to communicate with the outside world. In this case, that meant sending cheeky tweets. They originally used a Raspberry Pi for this, but found that the SD card kept getting corrupted. They eventually switched to an Electric Imp, which worked well. The Arduino sends a status update to the Imp every minute. If the status changes, for example if a beverage was dispensed, then the Imp will send a tweet to let the world know. It will also send a tweet to the maintenance person if there is a jam or if a particular slot becomes empty.

The Chaot is my contestant for the LMRv4 Donor Appreciation Robot Challenge. 

The machine creates a random number using physical chaos and combines the random numbers to an four digit index.
This index can be used to select a winner.

Content

• Draw Winner Using a Magnetic Pendulum
• Idea Finding
• The Making-Of
• Used Parts
• Current Issues
• Thanks To
• Further Reading

Draw Winner using a Magnetic Pendulum

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