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An Engineers journey from concept to 3D Print


I’m half way through my 10 week internship at RS Components where I am creating content for the members of DesignSpark. For the past couple of weeks I have been putting into practice my new DesignSpark Mechanical and 3D printing skills which I learnt through a FabLab workshop and during this placement. A project was set to create an earphone cord winder from concept to reality in order to home in my skills and prepare me for applications in the future. An earphone cord winder is something the cords wrap around in order to keep them neat and stops them from tangling in your pocket. After a bit of research looking through the online CAD communities I found many different cord winders of all shapes and sizes that do the job. I wanted to create one better so I put on my engineering hat and thought about how I could improve the designs already online. After a quick brainstorm I thought about adding an unravelling mechanism that makes my winder superior to the rest. 


I was struggling to think of a method that would allow it to spin but not come apart except for the standard nut and bolt technique. This was when I was informed that 3D printers are much smarter than I first thought. It is possible to print parts of an assembly inside each other with a gap separating them to allow movement but also keeping them permanently joined. This method made it possible to create an appropriate spinning mechanism and from there I built my design around it. The initial design more or less stayed the same throughout the whole process showing off a small and simplistic design that fits comfortably in your pocket. 


Although the overall design stayed the same there were many required alterations from the very first print to the 10th. Due to being new to 3D printing it was very much trial and error to understand the method and limitations as well as the strength of the PLA filament used. This is why I ended up with around 10 prototypes! The first problem I arrived at was the beam which connects the two parts together and allowed it to spin. The device was only 4mm thick and a 0.5mm gap had to be left for printing in order to allow movement which meant the beam had a diameter of 2mm. As you can probably tell the beam split once I tried to twist the two pieces apart. Therefore the area around the beam was increased on both parts in order to enlarge the diameter of the beam which improves the strength.


Once the alteration was made the winder was reprinted and returned with better results although it wasn’t spinning like I imagined it would. There were so many factors that obstructed the spinning therefore a few amendments and reprints were necessary to find the fix. The change that made a considerable difference was swapping the cable holding slots with the arches so the earphones would be wrapped more centrally. When the earphones are pulled the forces are around the spinning axis and not in external directions causing disturbance. It still wasn’t as smooth as I liked it to be so I extended the length of the beam and its surrounding tube. I also decreased the gap between them from 0.5 to 0.4mm to make sure it spun parallel with the axis. It was reprinted once again and when I tried unravelling with some earphones it spun well enough.


The next amendment involved the locking mechanism that prevents spinning when wrapping the earphones up. A couple of different locking techniques were tested but both were very hard to move initially and weren’t as smooth as planned. Therefore the gaps between the pieces had to be enlarged to ensure there was enough clearance. The grip on the lock was also redesigned taller with an improved grip to increase the ease of manoeuvrability. These alterations made the mechanisms slide easier but were still really hard to move initially and sometimes resulted in breaking the mechanism. I had a rethink and thought I might not actually need a locking system. I designed a couple of arms coming off the spinning part that would be held when winding up the earphones and then they’d spin around the users fingers during unravelling. 


The final required alteration did not include redesigning a part of the device, it involved changing how it was printed. It was always being printed flat on the side with the DesignSpark logo, unfortunately that meant the logo was printed poorly and in some cases couldn’t be made out. To solve this issue I rotated the model 90 degrees around the X axis to have it standing up on its bottom edge. This produced an excellent result with both of the logos visible. Also due to the standing edge being thin there were little supports leaving their mark which allowed for a smooth finish.


The method of making this earphone winder has taught me why 3D printers are essential for modern day inventors and designers. Prototypes can now be printed in a couple of hours as opposed to a couple of days where they would be handmade by a skilled worker. Now prototypes can be created wherever the printer is, enabling a trial and error approach to ensure that the new invention works perfectly. DesignSpark Mechanical allows for quick and easy tinkering on the designs to solve any problems experienced. Exporting the STI file from Mechanical and importing into DoraWare was fast and simple enabling a couple of altered prints a day. DoraWare was used with the RS Printer which I was very impressed with, it churned out the same quality products as the Makerbot and Ultimaker with minimal hassle and a much smaller price tag. Improving prototypes has never been easier with the addition of 3D printers allowing for experimenting of different techniques without the huge costs it used to hold.

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3D print files for this device can be found on Thingiverse - Spinning Earphone Cord Winder

LukeWebsterScott has not written a bio yet…

14 Aug 2015, 14:00


[Comment was deleted]

August 17, 2015 15:12

The RS 3D printer mentioned in the post is RS Part Number 828-6356 ... pn=8286356

Their is also a newer version that has a heated bed and prints with more filament types inc ABS, RS Part Number 862-5705 ... pn=8625705

0 Votes

August 17, 2015 13:34

In this post ( ... o_3d_print); picture number seven (counting from top to bottom) shows a 3D printer apparently sold/made/distributed by RS.

Can someone point out to what machine is it and where can I purchase it?

Thank you all.

0 Votes