What is it

A corner shelf and bracket for mounting a USB charger inside a piece of furniture, like the corner of a bookcase or unit, such as the IKEA Kallax in the picture/videos. That sounds super-niche but take a look at the pictures and think: yeah, I could do with something like this :-)

This was designed with a few goals:

1. The ports should be accessible from the front (not top/etc like some other holders on thingiverse)
2. The shelf should be strong, and no ports should be blocked by the structure
3. The USB charger should be held rigidly in place, so that cables can be easily pulled out or pushed in with one hand
4. It should be possible to remove and replace the USB charger without needing to unscrew anything from the support (so that it can taken out for travel, and then brought back and reinserted)

I believe I have achieved this: the shelf clips together with no screws, the only screws being the supports. The shelf is mounted into the corner of a storage unit so that the USB charger itself is pushed against the upper surface keeping it in place, and the shelf has a sturdy lip at the front to prevent forward movement, and a simple lock piece at the back to prevent backward movement. This lock piece simply slides into place in a groove in the shelf and also into a socket in the supporting wedge.

To remove the USB charger, simply unplug the power cable out the back, pull up the rear lock piece, and then slide the USB charger in reverse out the back of the shelf.

Please take a look at the video to see this in action.
https://youtu.be/g_qAGNxLdkA
https://youtu.be/uHExZCbGDzI

To mount this:
Insert the shelf into the two supporting wedges and the USB charger in-place (to ensure the top of the USB charger is pressed up against the shelf above it). Line up flush with the front of the side wall of your storage unit and screw in with two small countersunk screws

The benefit of mounting in a top corner of a shelf/storage is that it really enables the one handed operation, since the USB charger is unable to move in any direction.
The PA-T11 is almost but not quite symmetrical - it can be used just as easily upside down (in fact you can see in the photo - I've mounted this upside down, so that the power led is visible through the cutaway). So if you wanted to mount at the top-left corner of a unit, instead of top-right, that would probably work too. But the rear lock piece relies on gravity - it would not be possible to flip this upside down and mount into a bottom-left or bottom-right corner space.

Or, if you're not worried too much about the vertical movement (or are fine using two handed operation), you can mount this just about anywhere.

Printing notes

Please print the parts in the orientation provided:

• Shelf: with the triangular holes flat on the printing bed
• Wedge support: with the screwhole vertically
• Rear lock: on its square end, with the triangular plug at the top

For the wedge support:

• First, choose the right version of the wedge support to fit your screws
• 3mm thread diameter with approx 6mm head diameter, or
• 3.5mm thread diameter with approx 7mm head diameter.
• Don't forget to print two wedge supports!

Be warned: I had difficulty slicing this with CURA 4.7.1 / CURA 4.8 - it wanted to insert faces inside the countersunk screw hole (basically filling up the screw hole - which would make this unusable). I found that DESELECTING the following CURA setting enabled CURA to slice this correctly:

• Mesh Fixes : Union Overlapping Volumes

And even then, attempting to include two (or more) of the wedge objects in a single Cura slicing run still caused Cura to mis-slice it and block up the screw hole. So I needed to print one at a time. It's not so bad, it's a quick print.

How I made this

This is my first attempt at designing something in SketchUp that has:

1. clip-together parts that are easily printable without any support
2. countersunk holes
3. circles and angles and intersections of circles at an angle :-)

I'm using SketchUp Make 2017 (the one that's free for personal use) here.

I learned that creating a countersunk screw hole manually using SketchUp is hard! I'm sure there's a better easier way, using a different tool (or maybe SketchUp has some hidden options) but I basically did it the hard way: using the Circle tool, extruding and then widening at different stages, to create the shank, head, and path, and then using the Intersect Faces tool to cut this against the angled wedge face (I then needed to select the protruding parts and delete them, to complete the extruded hole).
And that wasn't even my first attempt, I tried a number of different approaches before settling on a way that worked for me.

I also learned that SketchUp seems to export broken STL when you do this :-) and I needed to use MeshMixer to clean up the results (but as noted, CURA also had difficulty slicing this, even after fixing the STL).

For the 'clip together' solution, I wanted to design something that could be printed with NO SUPPORTS. I wanted the shelf to be restricted from moving relative to the support wedge, but printing out a plug-and-socket would have required support, so I came up with the idea of an inverted triangular plug, mating with a triangular socket on the shelf. The shelf is printed flat so it doesn't really matter what shape that is, but the wedge support is printed on its end (due to the countersunk screw hole) and as a result, the plug must be printable end-up. The triangular plug itself is slightly flattened at the tip, which gives enough support to build subsequent layers, and the angle is high to avoid any overhang issues.

I also implemented a cutaway on the side panel of the shelf. Both the panel and the cutaway are functional: the panel prevents the USB charger from slipping out of place, and the cutaway lets me observe the power light indicator (see wireframes, and photo).

The dimensions of this are designed specifically around the USB charger I have, which is a AUKEY PA-T11 (a 6-port cabled USB charger).
Of course: you could remix this and use this for a different charger with different dimension - or any other thing, it doesn't have to be used for a USB charger!

List of updates

13 Nov 2020

• I tightened the tolerances a little (0.6mm) on the overall shelf length to reduce a bit of wobble/play when plugging or unplugging usb cables.
• I added a variant of the shelf support wedge with a different size countersunk screw hole (so 3mm or 3.5mm screws can be used)