For my manufacturing and design class
this semester (EK 156), we have a project where a group of three of
us have to come up with an idea for a product, design and model it,
make appropriate models and drawings, then manufacture and machine
it.
After our initial brainstorming session
concluded without any realistic ideas, I stepped outside, pulled my
camera out of my bag, and realized about a minute too late that my
group should make an L-bracket. I've thought about buying one
before, but they cost anywhere between anywhere between $60 and a
$160. Basically, they have two tripod rails parallel to both sides of
the camera's sensor instead of just the one usually found along the
bottom of the camera. This lets you mount your camera in both
landscape and portrait orientations.
I started by grabbing some calipers and modeling the the male mount of the tripod. I have a Dolica Proline tripod, which has a
similar shape to the Arca Swiss style mounts, but is slightly
smaller.
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| Dolica Proline Male Tripod Mount Cross Section |
With this modeled, it was fairly easy to pull dimensions from a camera, and get to work extruding. I have a Nikon D7000, but our goal was to make an L-bracket that could be used across many cameras. I knew that mine was quite large so we designed around that as an upper bound in terms of size, and made sure to make it adjustable (I'll get to that later).
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| Bottom Plate Drawing |
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Side Plate Drawing
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My two team members used my cross section and dimensions from my camera to model the base plate of the L-bracket. Fairly simple design. It has the channel to mount to the tripod, and two holes, and a slot. The slot is for mounting the tripod to the camera. Most camera's use a 1/4"-20 screw, but some heavier duty systems use a 3/8"-16. We went with the 1/4"-20 as it fit my camera as well as a majority of the cameras we were targeting. The other two holes are for mounting the side plate which I was in charge of.
I went ahead and did the design for the side plate of the L-bracket which I very quickly ran into issues with. My main goal was to avoid inhibiting the cameras functionality. My camera, and many like it, have little doors to access I/O ports like USB, HDMI, and 3.5mm jack for an external microphone. There are also controls on the front of the camera for autofocus that I didn't want to have to reach around to activate.
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| I/O |
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| Front Controls |
These two constrained the depth of the side plate, as well as the inner channel for the doors. I didn't realize until I sat down with SolidWorks and a caliper how thin the walls for the mounting channels would be. I initially modeled them at 3/16" each and hoped that when we got to machining, it would be doable.
Before machining, we had to decide on a material. Our initial idea was to machine out of Aluminum to match the original mount and the rest of the tripod. My wallet and I were a little skeptical of that, and after a conversation with the head machinist at our machine shop we decided to use High Density Polyethylene (HDPE). It is significantly cheaper and easier to machine than Aluminum which was important since this was our first real machining project. I talked with Bob, and he said that HDPE was the right choice for our project, but later down the line Aluminum would definitely be an option.
We ordered our HDPE from McMaster-Carr, and made sure to get enough for at least 2 L-brackets. With our material in hand, we got to work. Most of the machining would be on a 3 axis milling machine, and the 2 holes mounting the 2 plates togethere would be done on a drill press. BU's Engineering Product Innovation Center (EPIC, our machine shop) uses GibbsCAM for all of their CNC machines, so after importing our models there, and marking our operations, we sent it out to the machine.
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| Milling the Top and Side Plate |
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| Milled Side Plate |
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| Milled Bottom Plate |
With our plates off the CNC machine, all we had to do was put it in a drill press, and drill out the blind holes for the mounting screws, and mill the dovetail joint that makes the interface with the tripod mount.
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| Assembled L-bracket |
Here's the two plates screwed to eachother. These screws can be adjusted to account for the width of different cameras. The maximum width is determined by the length of the screws. We used 1 1/4" long 1/4" 20 hex head screws, but these can easily be swapped out for longer ones.
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| Assembled-L-bracket |
The slot on the bottom plate allows it to be mounted at different depths along the camera.
After using the bracket for about two months, I've identified a couple of issues that I want to address in the next version I make myself. The first issue is the length of the baseplate. I want it to be 1/4" longer than it is right now. This increases the length of the channel the tripod can mount to, and makes a better fit on the camera itself. The second major change is with the side plate. I know now that I can make the side plate deeper without interfering with the front controls. This would allow me ot make the side plate more sturdy. A welcome upgrade from the last version.
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Proposed Second Revision L-bracket
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From here, I'd like to machine this second version of the L-bracket, make sure it resolves my issues with the current assembly, then proceed to machine it in Aluminum when I'm confident with the design.
Disregarding the cost of machining, which to me was $0 (I pay tuition, but yeah), I payed $20 for a sheet of HDPE, and 3 screws. Much cheaper than mass produced products I was able to find that satisfied my requirements. Even with the issues I have identified in the current L-bracket, it is incredibly usable, and I am thrilled to be using it.
