A few years ago my wife got bit by the plant bug pretty hard and we accumulated a number of LED grow lights from Amazon that we no longer had a use for. They are bright and extremely light, making them an ideal light to use for my tech workbench in my office.
And, since I had just unboxed my first 3D printer, a Bambu P1P, I figured what better way to celebrate than to design some brackets to hang these lights with it, right?
In this article I’m going to go through the thought process I went through to design these. Even though the general idea is pretty simple, I wanted this project to be practice for learning the design process itself.
Establishing requirements
There were two key design requirements for the clip that attaches to the lights:
- Requirement 1: The lamp is securely held by the clip, and cannot be easily removed on its own, or by casually bumping the light, etc.
- Requirement 2: The clip can be easily installed and removed from the light with one hand. This must be safe enough to do on a stepstool or stepladder.
These requirements seem to contradict each other. But we can meet them by finding right spacing around the object.
Designing a clip that is secure… yet easy to install/remove?
The amount of gap (tolerance) we place around the object going into the clip (on all 5 surfaces that will meet) will determine how this clip will behave to a large degree. If we make the gap…
- Too small: It will fit nice, tight, and secure, meeting Requirement 1 (initially). But, it will be more difficult to install, and probably even more difficult to remove, because you’ll have to deform the clip more to install and remove the object. This will likely cause it to fail Requirement 2.
- In addition, having no gap means that if the materials expand and contract due to temperature changes, it could stress the brackets with repeated contractions and expasions, also likely leading to damage or failure. Thus, this solution puts us at more risk of failing Requirement 1.
- Because the clip must be bent further to open it enough to fit the light in, the material will be stressed more and this could also cause a failure – even on the first installation. Each removal and installation will increase the likelihood the part fails.
- Too big: If tolerances are too big, it will be very easy to install. Too easy in fact, because there will be certain positions or angles where the light can fall out of the bracket on its own, causing it to fail Requirement 1.
So we know that the answer is somewhere in the middle, there’s a balance where the clip is gripping enough of the edge to securely hold it, but there’s enough play to allow you to easily install and remove the light.
Designing for installation while on a ladder
Another design consideration is the process the end user has to go through for putting the light into this bracket. Installing this myself, with two brackets on the wall, I needed to make sure I can clip the light in with one hand while I hold the light with the other – all while on a stepstool – safely.
My first instinct was to design it like a trident, symmetrical and angled on both sides:
But this could cause some issues:
- Only one side of this clip would flex because the other will be anchored to the end of the bracket.
- The user has no clear indication of which side to start mounting the light into.
- The light could “roll” to try to settle into one side, and if not expected by the user, this could damage the light or cause the user to lose their grip or balance. All of which fail our requirements.
As a solution, I decided to square the left end of the clip, which will be the side facing the wall bracket:
With this squared, it creates a “shelf” that can be used to ease installation:
- Insert the back of the light into the clip. The clip will help hold the light in place.
- Slowly rotate the front side of the light up into the clip until you hear a snap.
The beauty of this motion is that it can be managed one-handed. Using both hands, you would bring the entire length of the light up to the brackets, seating it in both brackets against the back. It will mostly guide itself so this action is not difficult to do (but admittedly, still has some danger to it.) Then, once seated, it’s easy to reposition your hands to clamp down on the front of each clip to snap it in. This makes it satisfy our requirements of one-handed, easy installation.
How about removing it?
The removal process is basically the reverse of installation, and has the same one-handed, edge-of-thumb-grip feeling to it:
- Grab the top of the light fixture
- Using your thumb, roll it up under the corner of the clip
- Using your other hand, pressing the light firmly against the back of the clip, roll the fixture back down to release it from the clip.
The act of pushing the light against the back will maximize the gap on the front edge, and reduce the amount you need to deform the clip to release the light, thus making it also easy to remove with one hand.
Printing a prototype to test the clip shape
I extruded the shape to 35mm wide, as that was my original intention for the size of the clip. I only printed the parts that mattered to test the fit. This way, I didn’t waste as much time and materials if something was wrong.
I exported this to an STL, and printed it with the PLA Basic Black I got with the printer. I was pleased to find it fit and functioned perfectly on the first print!
Changes from the prototype
Key issues:
- The clip was a bit stiff and difficult to install and remove.
- The loud snap on installation, as a result, was also not pleasant (especially on a ladder.)
Changes made:
- Reduced the width of the bracket from 35mm to 25mm. With less material across, it was easier to bend the clip.
Adding the arm
With our bracket fitting, we’re ready to move into designing the rest of the bracket, namely the arms that will attach this to the wall. I basically started where the original clip left off and extruded it out to build the rest of the clip.
I wanted this to extend the light about 9″ away from the wall, which is a fairly long cantilever given the clip is now only 25mm wide. While these Amazon LED grow lights are extremely light, I know without any vertically-oriented bracing, these lights would be on my desk before next morning.
I opted to create a C-beam type shape, which allows for two #8 screws for mounting to the wall. The beams had a perfect place to end on the clip, a little taper to match the height will complete the design:
Installation
I mounted these both to studs for a solid hold. You could likely also get away with anchors, but I hate the giant hole those create (and your drill wandering to leave the damn thing 1/16″ off center.)