3D Printed Retrofit for a Tablet Stand

The Problem

I purchased this stylish tablet stand, and it worked great for a few months. One of its many features was that it rotated 180 degrees from portrait mode to landscape mode. After 3 or 4 of months of use however, the center axis loosened, and any up and down motion on the touch screen would cause the tablet to rotate. I otherwise liked the stand, so I decided to fix it. Since I almost always use it in landscape mode, I could have just epoxied it in place, but I wanted to maintain the rotation, and I wanted the challenge of fixing it. Here's what I did.

Tools and Resources

• 3 mm Hex Key Wrench
• Metric Ruler
• Tinkercad (free online 3D Modeling software) https://www.tinkercad.com/
• 3D Hubs (for 3D print) https://www.3dhubs.com/
• Pencil
• Double-Sided Carpet Tape
• Scissors
• X-ACTO knife

My first thought was to put rubber stops between the back plate of the front, and the horizontal axis of the stand as indicated by the arrows above. I tried all sorts of rubber bumpers, stops, odds and ends from the hardware store. All of them seem to work to some extent until I rotated the tablet. All of them were either too thick to conveniently rotate the iPad, or would peel off in the process.

So my next thought was to use some sort of thick washer or bushing that would provide extra friction between the back plate and the stand. I had a zip-lock bag full of small left-over packing materials (mostly foam, or rubber). These had come with various gadgets or cases I'd purchased over the years. I rummaged through the bag and found a foam ring that I thought would be the perfect size. I wasn't sure I how I was going to get it on the back plate of the stand, or if I could at all. I would first have to see if I could disassemble the stand.

Disassembling the stand turned out to be simple.

1. Lay the stand on its face.
2. Using a 3 mm hex key wrench, remove the two chrome screws from the back plate, and set aside.
3. Remove the back plate, and set aside.
4. To access the screws on the front of the plate, flip the bottom of the stand back on itself, while holding the face of the stand down on the work surface. The front screws will now be accessible.
5. Again with your 3 mm hex key wrench, remove the remaining two screws, and the shaft plate they secure, and set aside.
6. The base will now be free of the stand. Set it aside.

(I'll be showing how to reassemble the stand later in this Instructable.)

In the image above you see the tablet stand reassembled with the foam bushing in place. The foam bushing helped, but this ultimately failed too. It was too soft, and did not provide quite enough friction. Eventually it became permanently compressed in the horizontal position, and again the tablet began to annoyingly rotate. But I learned a few things along the way.

1. The basic bushing concept was a good one, but I needed a more rigid material.
2. The diameter of the inside opening in the bushing was critical. To install it, it would have to be stretched over the horizontal rotation shaft.
3. I determined that the best way to adhere the bushing to the back plate was with double-sided tape. I tried other adhesive methods with little success. I happened to have a roll of double-sided carpet tape. It is very useful stuff.
4. The foam bushing would be a useful model as I determined dimensions for the custom bushing I would eventually make.

A Custom Bushing

I had taken a 3D printing workshop, and I had recently learned the simple-to-use 3D modeling software, called Tinkercad, so I considered printing a custom designed bushing. But I set aside that idea thinking that the standard 3D printing material, PLA, was too rigid for this purpose. A few weeks later, I took another 3D printing workshop, and learned of Ninjaflex, a flexible 3D printable material that had become readily available. So I decided to create a 3D printed custom bushing. This would be my first 3D printing project.

Measurements

The most difficult part was measurement. I started by measuring the foam bushing with its compressed indentations. Then I made adjustments.

Having toyed with Ninjaflex, I had some idea of its properties. I knew it was definitely more rigid than my foam bushing, so the next thing I did was enlarge the center hole. Like the foam bushing it would have to stretch over the shaft. I also reduced the thickness of the design because I knew it wouldn't compress as much as the foam bushing. Deciding how much adjustment to these dimension changes was essentially an educated guess based on my knowledge of the differences between the two materials.

After settling on these basic dimensions, I went back to the stand, checked my measurements against the stand, and made few more minor adjustments.

Design Element

I decided it would be useful to add horizontal, and vertical "stops" to the bushing. For the size, depth, and even the shape of these stops, I had to make a best guess based upon measurement and interpolation of the indentations in the foam, the dimensions of the stand, plus what little I knew of Ninjaflex.

3D Modeling

This was the easiest part. I used Tinkercad. Tinkercad is a free, easy-to-learn online 3D modeling app. You essentially create 3D models by adding to, or subtracting from, basic solids. The bushing was a simple shape, and it was very easy to create in Tinkercad. I even made some slight modifications to the design in Tinkercad. In the top image, a screenshot from Tinkercad, you can see how I used two cylinders to cut away parts of the basic bushing for the horizontal and vertical stops.

Printing

Since I don't have a 3D printer, nor easy access to one, I saved the design as an .stl file (standard 3D printing format) and uploaded the design to a local printer via 3D Hubs.* You can upload your designs directly to a few select 3D printing companies directly from Tinkercad, but in this case, one of the printers in the 3D Hubs network turned out to be more convenient for me.

* If you'd like a copy of this .stl file, let me know in a comment.

So now I was ready to reassemble the stand with the new bushing. The first step was to attach the the new bushing to the back plate.

Applying the Adhesive to the Bushing

1. I attached a piece of double-sided carpet tape to the back of the bushing.
2. I trimmed the excess carpet tape from the outside with a pair of scissors, and removed the inner circle with an X-ACTO knife.

Aligning and Attaching the Bushing

This was going to be the tricky part. I needed to center the bushing around the central shaft, and align the "stops" so they held the tablet precisely in the vertical and horizontal positions. I decided I could do the former by "eye", but I would create a guideline for the latter.

1. Using a ruler, I made guide marks halfway across the back plate of the stand. It didn't matter which direction the center line went (up and down, or left to right) as long as it bisected the back plate through the center of its axis. I drew the line with a pencil which I knew could be easily erased from the aluminum housing. Ultimately, I would line up the centers of two the four indentations or "stops" in the bushing with this line.
2. Next, I peeled the backing off of the bushing.
3. I stretched the bushing over the cross bar being careful not to stick it down in the process.
4. With both hands each holding one side of the bushing, I "hovered" the bushing until I had two of the stops aligned with the center line. It was now fairly simple to center the bushing around the rotation shaft.*
5. Now that I had it aligned, I carefully placed it into position. I was fortunate to get it perfectly aligned on my first try. Then I squeezed it firmly to the plate.

* Next time I do this, I will make both horizontal and vertical lines, which would make "centering" unnecessary, as aligning the bushing with both axes would also center the bushing.

1. Align the small flat back plate with the back of the base as shown in the first image.
2. Screw this to the horizontal crossbar on stand face as seen in the second image.
3. While keeping the stand face flat on the work surface, flip the stand base over until it's nearly in the vertical position.
4. This step is a little tricky. Lay the rounded back plate over the horizontal crossbar. You'll notice that it doesn't just fall into place. The new bushing prevents this. Nevertheless, the bushing is flexible, and with a little firm pressure on both sides of the plate, it will snap into place.
5. Once the plate is in place as in the fifth photo, screw down the rounded back plate with the remaining two screws.
6. Flip the stand base back down, and you're done.

The bushing serves its purpose, it holds the tablet securely in both the horizontal and vertical positions, which were my basic requirements, but it still is not perfect.

The Design

The design was basically sound, and considering that I was estimating dimensions those were pretty good too. As it turned out the bushing was about a millimeter too thick. I was able to sand that millimeter off the bottom to make it fit. Another unanticipated problem was that the stand face was no longer able to flip 180 degrees back over on itself as had been possible without a bushing, or as it had with the foam bushing. This was not an essential requirement, but it was a useful feature of the original. The unexpected rigidity of the material may have contributed to both of those problems.

The Material

The material was far more rigid than I imagined. While the Ninjaflex bushing was flexible, it was far less compressible than I expected. I had previously held a number of small objects printed in Ninjaflex. To my recollection they were far more compressible than the bushing I received. I'm not sure if this is a fault of my lack of experience with the material, or the actual material I received.

The Takeaway

The basic design is sound, but before I try again, I need to become more familiar with the material, more familiar with 3D printing, and perhaps maintain greater oversight of the printing process, possibly even printing it myself.