Surface Duo Repackage
The duo is a superb device with a distinctly wide presence and an astonishingly awesome 3:2 aspect ratio. I have found it exceedingly excellent to use on a daily basis around the lab and it is an absolute joy to use for just about any task. The wider nature of the device improves everything about mobile computing. My fingers aren't cramped when typing. I can browse the entirety of Digikey in desktop mode with ease. I can use Firefox like a normal desktop user. Nothing appears minuscule on the display because of its astonishingly low device pixel ratio of just 2.5 and its adjusted resolution of 540x720 in folded mode or 720x1114 unfolded. In addition, the vari-angle display fends off all lighting glare with a simple adjustment. No longer do I need to rest the phone against something. It is simply invaluable for bench work and productivity.
Unfortunately, the Duo was designed to be more of a toy than a proper phone. Let me elaborate. Mobile tech companies have this never ending desire to win at phone limbo. Instead of a broom handle raised above the ground, they bend over backwards to reduce phone thickness for no apparent reason. The Duo's combination of absurd thinness (4.8mm per side), brittle materials, and a non-existent gap between the two sandwiched screens leads to a fiddly and frustrating user experience. The hardware is performant even in 2023, but the overall execution was hodgepodged to put it nicely.
My biggest criticism is that the Duo feels like it will fall whenever screens are switched - and I'm not one with particularly large hands. Since android 10 was not designed for multiple screens, the duo frequently hangs up switching between displays. The easiest way to resolve this is to close and re-open the phone. Normally, this would not be a problem on any traditionally designed device, but the gap between phone halves is a mere 0.045-0.065in or 1.145-1.651mm. This is simply too small of a gap for any human finger to feel purposeful at opening a hinge.
Luckily, closing the two displays against each other provides a reassuring "thunk" but having to do this repeatedly is quite annoying. The subsequent Android releases reduced these occurrences, but you can see where I'm going with this. The opening/closing experience is simply lacking with this phone. I'm after a more ergonomic solution, one that is tried and true and works every time.
A viable solution is to look at the 2008-2012 unibody Macbook pro. Apple implemented a simple rubber gasket that decorates all four sides of the laptop screen. The protruding rubber gasket is recessed from the display edges, leaving a nice gap for a fingernail or meaty part of a finger to slip into, simultaneously creating a nice purchase on the display of the device and adding sufficient padding. This allows for the Macbook to have a very normal and ergonomic opening process. It worked so well that Dell copied it in their Precision line of workstation laptops, shown above. Microsoft oddly skipped this critical design element.
Serviceability
I'm a sucker for fasteners. Yes, I don't mind seeing fasteners adorn my devices even if they are right front and center. I also remissness about the days of old when you could just swap in a new phone battery and be off and running. Meet the newly designed service bays. Standard Pan-head screws greet you and provide excellent positional fastening for the o-ring compartments. The compartment covers are an ABS plastic glass-fiber blend, with captive fasteners. The plastic covers are nice and rigid, easily replaceable and most importantly, RF transparent. The compartments provide easy access to the larger LiPO batteries and add compliant pads for even, mild pressure on the pouch cells.
Durability
I am not a fan of tape dependent phone cases and while the tacked on duo bumpers looks good enough, they tend to pull away from general phone use. This is not acceptable. I was inspired by the dell power adapters from yesteryear and implemented a simple recessed catch into the body of the Surface Duo. There's little machined grooves along the edge of the device that allow for the rubber bumper to fasten to the frame in a solid manner. A combination of these grooved recesses and tape should provide a better phone case experience. Additionally, those who like the phone to bear-it-all can install flush mount rubber pegs that provide a bit of grip to the sides of the phone, yet retain a narrower profile than using the bumpers. I think it's a nice and elegant compromise. If the grooves ever get full of gunk, they are wide enough to be easily cleaned with a toothpick. Thicker Tesa foam based tape is adhered to the back of the display offering more planar flexibility during impact, reducing shock and catastrophic damage to the display from an accidental drop.
Features
Extra thickness means extra features. There's a headphone jack now. A wireless charge coil also joins the party. No more mono speaker configuration, there's one on each side. More importantly, a rear mount camera and flash see the light of day. Ideally, I'd like to shove as large of a camera module as possible in this phone, but I'm still searching for an off the shelf module. Re-purpose a Lumix CM1 anyone?
Water Resistance
The original duo was not rated for any particular level of water ingress protection. Let's fix this. The sim card now features a standard o-ring. The usb-c port and headphone jack sit in a silicone potted machined cavity. The frame of the phone is 6061 aluminum with semi-isolated cavities for the volume and power buttons. The traditional tight weave mesh microphone screens with water repelling coating make their appearance as well.
The original hinge design was fantastic, but due to the additional thickness and heft of the redesigned Duo, the hinges need some beefing up. A scaled up design will do. Unfortunately, the hinge acts as a primary source of water and particulate ingress. One of the most rugged military laptops of all time, the Getac A790, uses a simple cable hidden inside the display hinge - just like the Duo. The secret for a weather-proof hinge is dedicated meandering compartments on either end of the hinge for the cable to snake through along with copious amounts of silicone. It is simple, robust and effective. If this is good enough for Desert-Storm conditions, it's good enough for a phone.
Design for...Manufacture?
What makes this design so unique is how much of the original device is reused. Yes, this is a project for a crazy man, but it is possible to duplicate with the right tools. Once the frustrating process of removing the Duo's displays is completed, its relatively smooth sailing from there. Many thanks to the lovely folks at ifixit and jerryrigeverything for the very risky early teardowns.
The most fiddly aspect is soldering on the additional flex cables used for the additional features. The added headphone jack, NFC coil, and back camera module will require micro soldering experience. While this is a very complicated and delicate process, it is indeed possible. I have designed this repackage process in CAD in anticipation of heavily discounted future access to a CNC. I'm in the middle of a 1990s Anilam 3-axis CNC repair, and I'm almost home free, but more on that another time.
The moon and stars must have aligned because I ended up scoring a stash of 14 broken Surface Duos on ebay for a song and a dance toward the middle of 2022. They were not flawless by any means, and they all required some form of attention. Some had broken LCDs, some had faulty digitizers, some bad USBc ports, while others were software locked. Most importantly, all 14 devices worked. They all booted up, they all have functional buttons and most were not bent, which is a huge plus.
Here's a closer look at the for-parts lot of goods. Thanks again for everyone who commented and chimed in, this is a very interesting and oddball project indeed.
Want more? Here's a behind the scenes look at my workspace and some of the images that did not make the cut to be included in the write-up:
