Homemade wateproof cell phone mount from a fly fishing box

RCinNC

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I decided to put an old Droid Turbo into service as a GPS unit on my bike, but I wanted to be able to waterproof it so I didn’t have to worry about rain, or water crossings. I’ve done the plastic sandwich bag routine in the past, but I don’t like it (plus I wanted something that was actually waterproof), so I began looking around for something I could repurpose into a waterproof case. I stumbled on a fly fishing accessory that fit the bill perfectly.

The item is a Maximumcatch two sided waterproof fly box; it’s what fly fishermen use to hold their flies. I bought the large one, from Amazon, for about 13 bucks.


This is what the box looks like in its pristine state. And here’s what I did to adapt it to the cell phone:



The first thing was to remove the foam that holds the flies in the box. The foam was removed from both sides of the box. I didn’t want the foam in the box, even though it provided some cushioning, because I wanted to be able to open the cover on the box if necessary and I didn’t want the phone falling out.

Those holes you see around the edges of the floor of the box aren’t there when it’s new; I drilled those in the box in order to attach some parts later on.



Next, I removed one of the lids. The boxes are two sided, with a watertight lid on both sides, but I only needed one side. I pushed out the hinge pin with a small drill bit until I could get a hold of it with some needlenose pliers, and then pulled the pin out far enough to remove one of the lids. I’d recommend either taking the lid off or covering it with masking tape while you’re working, to keep it from getting scratched.




Each door has a latch, and one has to be removed. I did the same thing as with the lid; pulled out the pin far enough to take off the latch (on the same side of the box as the removed lid).




The rubber gasket was removed from the gasket channel on the unused side of the box. This is the side where eventually the ball mount will be installed. I’m going to hang onto it and keep it in my spares box, in case the remaining one ever leaks.




I removed the inner wall of the gasket channel on ball mount side of the case the with an Olfa knife and a set of hobbyist sprue cutters. You don’t have to do this; I just did it because I thought it would look better on the finished product.




Here’s the ball mount side of the case, sanded down flush.




This is the magnetic plate, that actually holds the cell phone in place inside the mount when the lid is open. The magnets came from one of those cell phone mounts that you stick into the CD player slot in a car, and a metal plate you stick on the back of the phone holds the phone to a magnet on the mount. I had an old one laying around that was about to get thrown away, so I cannibalized the magnetic part of the mount. The plate is made out of 1/8” ABS sheet, and I cut a hole in the center that was the same shape as the magnetic mount. I glued the magnetic mount to the plate with Weld-On, and reinforced it with JB Weld.




This is the rear of the magnetic plate. The white plastic is .030 polystyrene. It’s there as a shim, to get the cell phone to the correct height so that, when the lid is closed, the lid itself holds the cell phone in place to it can’t move around at all.




Just a close up of the magnets.




This is the mounting plate for the RAM ball, made from 1/4” ABS. The side you see here is the side that faces out from the mount. I used a piece that thick mainly because it makes it possible to recess all the attachment nuts into the plate so they don’t stick up anywhere. It just makes it a little more streamlined. The six #6 nuts around the perimeter of the plate were placed into 3/8” recesses drilled into the plastic with a Forstner bit. I bored about halfway through the 1/4” sheet; that’s deep enough to get the machine nuts below the surface of the sheet. Once the machine nuts were in the recessed holes, they were fixed in place with JB Weld. The squares were cut out of the plate just to make it a little lighter.




This is the other side of the plate. Those are #8 machine nuts, set into 3/8” recessed holes and fixed in place with super glue and accelerator. There wasn’t much clearance between the flats on the nuts and the recessed holes, so I used superglue that would flow easier into the holes and around the flats, rather than the thicker JB Weld.




This is the case with the magnetic plate and the mounting plate installed. The screws go through the six holes in the magnetic plate, through the case, and into the recessed nuts on the mounting plate. I ran beads of RTV silicone adhesive/sealant around all the screw holes and on the undersides of the screw heads, to maintain the watertight seal of the case.




This is a standard 1” RAM ball mount with a diamond base, installed on the mounting plate. The ball cost $6.99 on Amazon.




This is what the case looks like from the front with the magnetic plate installed.




Here’s the Droid Turbo in the case. The magnets are pretty strong; I wouldn’t trust them alone if I was bouncing down a potholed road on the bike, but they actually aren’t what holds the phone in place when you’re riding; the lid of the case does that. The magnets do hold the phone inside the case, even when the case is vertical, when the lid is open.




This is what the active phone looks like through the lid of the case. The clarity of the plastic is excellent, with no distortion.






And here it is, mounted on my handlebars.

I have $20 in the project, though I did already have the magnetic phone mount. I also have sheet plastic on hand from a zillion other projects I’ve done, so I didn’t have to buy any for this one.

As always, I post these DIY projects in case there’s another nut out there like me, who wanders through hardware stores looking at aluminum angle and plumbing supplies and wonders “hmmm, what can I make out of this?”.
 

WrongLane

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I had done something similar a couple years ago, worked great except when in direct sun. The phone would overheat and shutdown.
 

RCinNC

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I had done something similar a couple years ago, worked great except when in direct sun. The phone would overheat and shutdown.
I've heard that from others. So far I've had it out in the sun for several hours with no issues, but obviously that isn't the same as what the sun will be like in June or July. I'm working on some way to vent the case when the waterproof feature isn't necessary, so the overheating won't be a problem.

The bigger problem I've run into is battery life. I'm using an older Droid Turbo, circa 2014. Even with a brand new battery in it, the battery life when running OSMand continuously is about 3-4 hours. That's not enough for a standard days' riding. So now I'm working on a way to get power to the phone and still keep the waterproof feature intact.
 

RCinNC

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Does the capacitive screen still work inside the box?
Well, yes, the screen still works on the phone, but no, you can't manipulate the screen when the lid is closed. The lid is hard plastic, and isn't designed for that sort of usage. That wasn't a problem for me, as it's easy to unlatch the lid and do whatever you need to do on the phone.
 

WrongLane

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RCinNC

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There's no room in the case for anything but the phone. I chose the case specifically because the phone would fit tightly inside it, so there wouldn't be enough room inside the case for the phone to move around. A case would have to be the size of a mini ipad to fit that particular wireless charging stand inside it.

Ideally a waterproof phone would make it easier, but I didn't have one of those. The project was a way to repurpose some free and inexpensive items into a usable waterproof GPS system. It definitely works for that purpose, but it does need a couple refinements if I want to address those issues of power and heating.
 

RCinNC

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Well, I've come up with a solution for how to power the cell phone while it's in the mount, and still maintain the waterproof integrity of the box.

I didn't get any photos of this component under construction, but it was fairly simple. It looks like this:


First I cut a hole in the lid of the waterproof box that corresponded to the location of the USB port on the cell phone. I did this with a drill, and then squared the hole with a needle file.

Next I made the foundation for the waterproof door for the lid of the box. It's a piece of 1/4" thick aluminum from my scrap box. I held the block up against the lid in order to transfer the location of the hole in the lid to the aluminum block. I then drilled out the hole in the block to match the one in the lid, and tapped two 6-32 holes in the block to serve as the attachment points for the waterproof door. In order to get the aluminum block to match the contour of the lid of the waterproof box, I mixed up some Steel Stik epoxy putty and spread it across the top rear part of the aluminum block. I put some masking tape along the lid of the box to prevent the putty from sticking to the lid, then pushed the aluminum block against the lid. The putty follows the lid's contours, and I sculpted it to make sure the joint between the aluminum block and lid was smooth. I left the aluminum block on the lid for about twenty minutes, then popped it off. I smoothed out the putty with sandpaper, and then boxed in the top and sides of the aluminum block with .040" ABS sheet. That was done basically to hide the epoxy putty.

After the aluminum block/putty/ABS sheet combination had set, I attached the aluminum block to the lid of the waterproof box with JB Weld. I made sure to mask around the area with masking tape, so there was no chance of the JB Weld getting onto areas of the box lid that I didn't want. I let the JB Weld set overnight.


This is a closer photo of what the contoured side of the aluminum block looks like, after the block was fastened to the lid of the waterproof box with the JB Weld.


This photo shows how the hole in the aluminum block lines up with the corresponding hole in the lid of the waterproof box.


This shows what the block looks like from the inside of the waterproof lid.

I couldn't find any small threaded knobs at the hardware store that would fit with this project, so I made my own. They're just a couple sections of telescoping styrene tubing, placed inside each other to make the knob as wide as I wanted. I cut off the head of a 6-32 machine screw and put this through the center of the tubing. The screw was then cemented in place with JB Weld. After this all set, I used a small needle file to cut the finger grooves into the knobs.


These are the knobs after shaping.


These are the knobs after being sprayed with truck bed liner.


This is the waterproof lid that covers the power opening in the aluminum block. It's made from a scrap piece of 1/16" hardware store aluminum angle. The gasket was made from a small piece of 1/16" neoprene rubber.


Here's the waterproof door with the attachment knobs installed.


The waterproof door screws into the aluminum block on the waterproof lid, and the neoprene gasket makes a water tight seal between the door and the block. The JB Weld makes a waterproof seal between the block and the lid of the box. When the lid of the box is closed, and the aluminum waterproof door is screwed down, the watertight integrity of the box is maintained.


When I want to power the phone externally, I just have to unscrew one of the knobs and move the aluminum door out of the way towards the rear of the waterproof box.


This is the USB power cable installed.

It's true that the box is no longer watertight when the aluminum door is open. However, the box is sufficiently water resistant that it can remain plugged in to external power even during heavy rain with no issues. In the event that I need the watertight feature, like for a stream crossing, it's simple and quick to secure the waterproof door.


Here it is on the bike, with the waterproof door secured.


And here it is, powered up.

I did submerge the box in my sink at about 8 inches to test the integrity of the waterproof seal. I left it there for a half hour, with no leaks.

Like a lot of systems, it's not perfect. If the USB power cable is installed, I can't open the lid of the box without removing the cable, so that'll make for a little more effort if I have to manipulate the phone screen.

I still don't know if overheating will be a problem, so I'll have to wait or some warmer days to evaluate that. If it does become an issue, I'll probably make a vent on top the case similar to the waterproof door on the bottom, but I'll save that project until I see if I actually need it. Might be simpler just to open the lid on a hot day.
 

Kruzzin5

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Well, I've come up with a solution for how to power the cell phone while it's in the mount, and still maintain the waterproof integrity of the box.

I didn't get any photos of this component under construction, but it was fairly simple. It looks like this:


First I cut a hole in the lid of the waterproof box that corresponded to the location of the USB port on the cell phone. I did this with a drill, and then squared the hole with a needle file.

Next I made the foundation for the waterproof door for the lid of the box. It's a piece of 1/4" thick aluminum from my scrap box. I held the block up against the lid in order to transfer the location of the hole in the lid to the aluminum block. I then drilled out the hole in the block to match the one in the lid, and tapped two 6-32 holes in the block to serve as the attachment points for the waterproof door. In order to get the aluminum block to match the contour of the lid of the waterproof box, I mixed up some Steel Stik epoxy putty and spread it across the top rear part of the aluminum block. I put some masking tape along the lid of the box to prevent the putty from sticking to the lid, then pushed the aluminum block against the lid. The putty follows the lid's contours, and I sculpted it to make sure the joint between the aluminum block and lid was smooth. I left the aluminum block on the lid for about twenty minutes, then popped it off. I smoothed out the putty with sandpaper, and then boxed in the top and sides of the aluminum block with .040" ABS sheet. That was done basically to hide the epoxy putty.

After the aluminum block/putty/ABS sheet combination had set, I attached the aluminum block to the lid of the waterproof box with JB Weld. I made sure to mask around the area with masking tape, so there was no chance of the JB Weld getting onto areas of the box lid that I didn't want. I let the JB Weld set overnight.


This is a closer photo of what the contoured side of the aluminum block looks like, after the block was fastened to the lid of the waterproof box with the JB Weld.


This photo shows how the hole in the aluminum block lines up with the corresponding hole in the lid of the waterproof box.


This shows what the block looks like from the inside of the waterproof lid.

I couldn't find any small threaded knobs at the hardware store that would fit with this project, so I made my own. They're just a couple sections of telescoping styrene tubing, placed inside each other to make the knob as wide as I wanted. I cut off the head of a 6-32 machine screw and put this through the center of the tubing. The screw was then cemented in place with JB Weld. After this all set, I used a small needle file to cut the finger grooves into the knobs.


These are the knobs after shaping.


These are the knobs after being sprayed with truck bed liner.


This is the waterproof lid that covers the power opening in the aluminum block. It's made from a scrap piece of 1/16" hardware store aluminum angle. The gasket was made from a small piece of 1/16" neoprene rubber.


Here's the waterproof door with the attachment knobs installed.


The waterproof door screws into the aluminum block on the waterproof lid, and the neoprene gasket makes a water tight seal between the door and the block. The JB Weld makes a waterproof seal between the block and the lid of the box. When the lid of the box is closed, and the aluminum waterproof door is screwed down, the watertight integrity of the box is maintained.


When I want to power the phone externally, I just have to unscrew one of the knobs and move the aluminum door out of the way towards the rear of the waterproof box.


This is the USB power cable installed.

It's true that the box is no longer watertight when the aluminum door is open. However, the box is sufficiently water resistant that it can remain plugged in to external power even during heavy rain with no issues. In the event that I need the watertight feature, like for a stream crossing, it's simple and quick to secure the waterproof door.


Here it is on the bike, with the waterproof door secured.


And here it is, powered up.

I did submerge the box in my sink at about 8 inches to test the integrity of the waterproof seal. I left it there for a half hour, with no leaks.

Like a lot of systems, it's not perfect. If the USB power cable is installed, I can't open the lid of the box without removing the cable, so that'll make for a little more effort if I have to manipulate the phone screen.

I still don't know if overheating will be a problem, so I'll have to wait or some warmer days to evaluate that. If it does become an issue, I'll probably make a vent on top the case similar to the waterproof door on the bottom, but I'll save that project until I see if I actually need it. Might be simpler just to open the lid on a hot day.
Great job and ingenuity!
 

RCinNC

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Well, some testing of the mount revealed a weakness; the JB Weld did not make a good bond between the clear lid and the aluminum block, and the block (which contains the waterproof door) broke free. I had some reservations about this during the design; JB Weld doesn't stick to some kinds of plastic, and whatever the clear lid is made of, it fell into that category. The solution was to use mechanical fasteners to hold the aluminum block to the lid.



I remade the aluminum block in the same manner as the original, and made the waterproof door a little narrower. I tapped two additional 6-32 holes in the block, and countersunk two holes from the inside of the clear lid. The block was then screwed to the clear lid using two 6-32 screws.



Before the aluminum block was screwed to the clear lid, I put a bead of clear silicone caulk around the perimeter of the block. It was then attached to the block with 6-32 screws, and the bead of silicone was smoothed out.



Since the waterproof door is now a little narrower, the original knobs I made couldn't be used because they were too wide in diameter. They would have interfered with the fit of the USB power cable. I made a couple smaller knobs in the same manner as the originals.



The waterproof door opens in the same manner as before, but since it isn't as wide, it doesn't stick out as far behind the mount as the original did.

I did the same waterproof test as for the original design, and I'm still good with submersion. I just wanted to post this update in case anyone out there decided to replicate this, so I could save them the trouble of trying a design that didn't work out.
 
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