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MP3 Player Amplifier

Posted by dougw Top Member Apr 24, 2016

I seem to often have a need to test small speakers, but audio sources these days tend to expect the speakers to have their own amplifier built-in. Rather than always having to hijack some other system and rig up appropriate amplifiers and wiring I decided to make a small test device that can directly drive speakers as low as 4 ohms. Originally, I was just going to build an amplifier, but I found an MP3 player with built-in amp for a ridiculous price of $1.78 with free shipping so this is what I built....


MP3 Player

MP3 Player Lid

MP3 Player Chassis

The idea to make yafrd (yet another filament roll dispenser) originates trying to 3D Print some of these useful support available on internet. Unfortunately I too frequently find objects (and not only in this case) that "in theory" will work perfectly but then when having the components in your hands arises mechanical issues making them almost useless or very difficult to use or build.


Some of the tools I tried was too complex, other was too expansive and in some cases requiring components that was not worthy.

The idea of a filament support like the one shown in the image above was attracting for several reasons, first of all the very small size. With a similar design I found a project using bearings and a complex format for the rotating parts to be considered just an inspiring idea.

I note a curious fact in many projects published ready for download and print on specific sites; one for all  Exploring the tons of project you can find on this site it is frequent to find very good ideas with incomplete parts, as well as projects granted to work by the author but without any image of the final result.

Project aims

Thus, I decided to create one the minimal needs requested to satisfy the reliability was the following:

  • Easy and not too much time-consuming components
  • As less components as possible
  • Easy to use in different conditions, including to be fixed
  • Very few external components needed
  • Robust and durable


The design

The following images shows the CAD parts (designed with Rhino 3D v. 4)

SH-3D03.png SH-3D01.png


The spool is placed on a couple of modules and every module has two wheels that should rotate freely keeping the filament roll in place. To make easy the 3D printing of every wheel it is compound of three pieces assembled as shown in the image below.


Remain two mechanical problems to solve without using a couple of bearing every wheel, redundant for the scope of this tool. The first problem is the screw that should be closed firmly but should not block the rotation and the second is that locking the Allen screw the support should not be deformed. The solution adopted is a double-axis on every wheel, as shown in the following quoted design.

Screen Shot 2016-04-19 at 16.46.42.png

The internal axis (the red one in the design) has an internal diameter of about 4 mm that remain fixed by the Allen screw. The compound wheel has an internal diameter that is about 0.6 mm wider than the internal axis so that the wheel can rotate freely. The compound wheel is also 1 mm shortest than the internal axis (respectively 11 mm and 12 mm) When the screw is locked the external border remain fixed to the internal axis and the drive wheels can freely rotate.

The assembly parts

The following images shows the components to assemble the tool. As you can see, two M4 10 mm Allen screws and two nuts are needed to keep together the wheels. Optionally the four holes on the base support can be used to fix the couple of rotating supports on a base.

IMG_20160409_175255.jpg IMG_20160409_194853.jpg

IMG_20160409_195017.jpg IMG_20160409_195433.jpg

The tools in use

The following images show how the support is kept in place and how it works.



The fully assembled product or the assembly kit is also available on

See also the Instructable 3D Printer Filament Spooler Support Assembly Guide


Curios 3D printed sun clock

Posted by gihu Apr 17, 2016

Hi all,


I just wanted to share with you something that I have recently seen, despite of probably many of you have seen it before...

It is a digital-style sun clock, here is the link


For sure there are in this community people who can improve it !!


3D Printed Phaser

Posted by dougw Top Member Apr 16, 2016

3D printers are great for printing iconic props from the movies. Here is my version of a Star Trek phaser:

If you need the file, let me know.


Triple Gaff 3D Print

Posted by dougw Top Member Apr 2, 2016

The Triple Gaff project is a solution to carrying heavy objects with narrow handles that cut into your fingers.

The Triple Gaff has hooks that grab narrow handles on objects to be carried, but the handle of the Triple Gaff has a large diameter to distribute the load over a larger surface area thus translating the concentrated high stress load from a narrow handle to a low stress load.

The shape is designed to be 3D printed with no support structures.

Triple Gaff

It can prevent finger pain while carrying grocery bags, garbage bags or paint cans.

Plastic Bag Gaff

Paint Can Hook

A paint can puts over 30 psi on the fingers, which is enough to cut off circulation and if carried for any length of time will become painful.

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