Simple Handheld Rewinder

Hi everyone, this is my first instructable, i'm a DIY enthusiast and i regularly check the projects created and published in this page.

For about 2 weeks my wife got into sewing and we try to get the cheapest materials for our hobbies. By doing so sometimes the materials might not come in the correct form for us to work and we need to workaround in order to turn them into the correct form. Some sewing machines allow to transfer thread from a larger yarn or bobbin (sorry if i name the things worng) to a smaller one, now i don't know if her machine has that ability or not but my wife kept tranfering the thread manually. Therefore i came up with a idea of using some stuff i had saved for a possible use.

A few years back i salvaged motors from printers and other eletrical devices, and kept them for no good reason other than for a possible DIY project. My idea was to use a motor in a simple setup in order to transfer the thread between bobbins/yarns. I searched for the motors datasheets and found that most of these motors (DC in this case, but there are alot of step motors also) dont have datasheets, so i had to tested the motors in a test bench power supply to reverse engineer them safely. Most of these motors are 5 Volt or 12 Volt. Since i had a bunch of 18650 Li-ion battery cells that i got out of a laptop battery i tested the motors for the nominal voltage of these batteries 3.7 V and full charged voltage 4.2 V with the test. There batteries have the most energy density vs price tradeoff, that's why they are used in most laptop batteries and even in the Tesla electric vehicles.

The motor i chose started spining at around 1.5 V and increases speed as the voltage increases. Tested it with a potentiometer so that i could regulate the rotation speed however for voltages under 4.2 Volts the speed isn't a problem. Therefore i just used a two way switch to turn on and off the motor. Why a two way switch you might ask?! I actually have a 18650 battery charger however if it fails i need a way to charge the batteries, so i need an extra 2 wire connection so that they can be charged by an external power supply. For that the battery terminals were set at the common pins, another 2 wire connection to the motor wires and the final 2 wire connection left loose for some sort of charging device (if needed).

The good thing about this type of motors is that you can switch the two motor wires without any problem, since will be my wife using this i feel much safer. Changing the wires will only change the direction at witch the motor shaft spins.

Wiring is done but the shaft ending isn't proper for anykind of yarn my wife had, so i glued a wall plug with hot glue big enough to hold the one her sweing machine uses most. The big deal with this step is to make sure, or at least try, that the wall pulg, or whatever you could use, is aligned with the shaft otherwise this will not work.

Then is just a matter of having the empty bobbin attached to the motor (wall plug) and the bigger bobbin or yarn in some sort of rolling axis, i used a lint roller and voilá!

Hope you enjoy