ZeroWriter Ink Clam-Shell Enclosure

A clam shell enclosure retrofit system for the upcoming ZeroWriter Ink digital typewriter.

6/12/25

So I've had my PoC hinge on my desk, and it has become a fidget toy of sorts; a good way to test the long term usage reliability. It's a good thing I did, because the hinge has developed a good amount of 'wobble' between the two halves. It seems to be something with the center pin, it has a significant amount of wiggle in all axes. I'm not entirely sure if its poor design or if I damaged it in some way during my experimentation. Disappointing regardless. I will have to test the second hinge to see if the problem occurs again. I'm waiting to hear from Southco about this issue and whether its normal or a fluke. 

If the Southco hinges turn out to be duds, I may have to move back the original screw in ones or figure something else out. Which is fairly disheartening to be set that far back. I'm almost considering just hacking together a DiY torque hinge with nuts/bolts/washers. That or go the easy way out and utilize a normal barrel/pin torque hinge; not as pretty but...

I've also been working on the lid design. Considering the Zerowriter is slated to start shipping this month, nothing is set in stone until I can start fitting parts and have CAD files. My concept at the moment is similar to my first crack at a e-ink writer design. This will use the IO directly on the inkplate. It also has the added benefit of using less material and being lighter. Most importantly, however, is that this will allow me to split it more seamlessly into three parts to allow for printing on a standard size print bed (not shown in below concepts, but i'm working on it).

6/3/25

So after some addition monkeying, I've further refined the hinge. The major difference is that left hinge now also includes a wire-passthrough channel and some dimensional changes. There will be some further leg work once I have physical hardware regarding that passthrough. I will likely need to develop a extension cable solution that can be easily fed through.

A design is never 'complete' for me, so I will undoubtedly continue to refined and tweak moving forward and as I discover needed improvements. That said, I'm happy with the base design concept. I think it's  in a very good place  to move forward.

Also worth noting, my previously mention laptop clasp idea pretty much failed out of the gate. Physical laptop latches are just too difficult to source. But given how well the friction hinges function, it's probably for the best. I'm experimenting with physical strapping to prevent accidental opening. That or I'll be going back to magnets.

Admittedly I'm getting a bit burnt on hinges for now, so I'm taking some time now to focus on the physical enclosure, specifically the 'lid' portion. I don't yet know a lot important dimensional details, so my focus is working out the general concepts and then scaling/adding details once the CAD files are available. For example: the texture and attachment of back lid plate, general profile, and (if applicable) closure strap attachment.

5/30/25

So the first official iteration of the hinge work far better than I could have hoped. The keying worked so well the hinges easily stayed in place without the screws. Some minor tweaks needed to the tolerances and shape, but the concept worked really well. This design allows for nearly 180 degree motion, which actually allows the keyboard to set to upward angle instead of flat. I will try to incorporate this into the final design, because its a nice little unintended feature. These hinges also eliminate that spring back/dead zone the other hinges had when closing the lid. These means whatever closure system I use really only needs to prevent accidental opening, rather than being physically shutting the lid fully.

The only issue with these hinges, unfortunately, is the cost of the torque hinge. I will have to see if I can find a cheaper supplier in order to keep the overall cost as low as possible.

I'm going to shift focus a bit and get the cable passthrough portion ironed out as its the final major piece of the hinge assembly needing to be finished. I may try to incorporate it into one of the hinges, but we'll see. 

Here are some concept renders showcasing the hinges.

5/28/25

I think we have a winner! Southco sent me the incorrect hinges (larger and higher torque value), but I was pleasantly surprised that they work very well. The action is smooth and satisfying, I was sitting all day fidgeting with my test print. After my initial PoC, I've changed my gameplan slightly regarding the final design.

• Instead of integrating the hinges into the lid and base itself, I've decided to design them as independent parts. They will be assembled then attached to the lid/base. This allows me to print them in the most ideal orientation for strength and accuracy. It also allows for fairly easy replacement of the entire hinge unit if needed.

Even if I go with a different sub-model hinge, the overall design will remain the same. So now I'm starting the nitty gritty of finalizing the design.

• I need to further refine the slot profile. Because of the taper of the hinge and slight tolerance variances I need to make sure they easily and snuggly press into place. Just a lot of tolerance tweaking here.

• I also need to develop the mounting solution of the hinge assemblies to the lid/base. My plan is to both use a keyed profile and screws to secure it. It's gonna be important that things fit snuggly and prevent any movement, so I may be experimenting with the best profile/design. 

Feels good to be past to testing phase and finally start some 'real' progress towards to final design. Should have some first versions designed in a couple days.  

5/27/25

Still waiting for some parts to arrive, so a bit of a lull in the prototyping action. I drew some basic concept art for an enclosure based on the Southco hinges. Still missing a lot of details, but gives an idea of shape and form. Once again, once I can get my ZeroWriter in hand along with the CAD files things will become far more refined, smoothed out, and hopefully even thinner. 

Since the ZeroWriter is a slab design, it's likely I will have a weight balance issue between the lid and the base. This may cause the unit to tip over when the lid is open. I don't yet know how bad this imbalance will be. It's possible it can be overcome simply by tweaking the design, making the base print denser (and thus heavier) than the lid. Worst case, I will have to include weights in the base. Not a terribly difficult issue to resolve, but something I will have to keep in mind. 

I've order a variety of different off-the-shelf clasping systems I want to play around with. Including some laptop latches from old Thinkpads/Dells. These laptop latches may offer a very sleek solution if I can get them to work with the 3d printed enclosure. Other issue may be availability. Modern laptops have all but forgone the use of mechanical lid latches, so unless I can find a supplier I will be stuck with the unpredictable used market.

For the most part, most these are purely experimental. I may find that none of them offer a compelling solution, and revert back to good ole' magnetics 

I'm also been thinking up a more primitive strap latching system (like I mentioned earlier). My current vision is the use of flat nylon webbing; possibly with it also being able to be used a carrying handle of some sort. Also it being easily swappable to allow for some customization. 

5/22/25

So a partial PoC print showed an unexpected issue. Although the hinge pressed in without issue with a little help from a clamp, I found that cycling the lid worked out the hinge, and it pops out after a couple rotations. Either the tolerances need to be much tighter, or I will need to add passive retention (like a grub screw or end cap). I'm gonna shelve these hinges until the other ones from Southco arrive, I want to try those before fiddling with it further. Those (southco) are tapered, so they may just end up working better. I'm also fairly certain 0.2Nm total may too much for this application. 

5/22/25

A small update the ongoing hinge testing. Designed a PoC for the press fit hinge, and its on the printer and I'll update once I get hands on with it. 

Some samples are on their way from Southco (Southco ST-4A-3S-33). These have the lowest torque value of all the options (0.03Nm vs 0.1Nm). My PoC's so far show that 0.1Nm to be a bit too stiff, but this is also small scale. This is likely to change once you put them in a fully loaded and full scale device. But I like to have options.

This design incorporates a totally press-fit / friction type attachment. Now this eliminates the need for heat inserts, a possible failure point. It also makes the overall assembly process easier. I do have some concerns and I will have to see have testing plays out. 

1. Over time, it is possible that the movement of the hinge could enlarge the mounting hole, causing loose hinges. This is highly dependent on many factors (design, material, etc), so the only way to really confirm this will be rigorous testing.

2. Replacement of the hinges would be challenging for the average user. Press fitting it in is rather simple, but removal would be far more challenging without damage to the enclosure or special tooling. I may be able to design around this. It also is possible that this is a non-issue if the design proves reliable enough.

3. My current supplier notes that a tolerance range of 1-3mm is normal. This is number is unacceptable for this design, as tolerance needs to be very tight and I don't expect users to measure their hinges and make adjustments to the design before printing. If I do select this hinge moving forward, this something I will need to address. 

4. The lid hinge ear is a potential weak point due to the print layer direction. Again, that joint could be more than tough enough, so I need to do torture tests to confirm. But in theory the horizontal layers offer significantly less strength in an area that will see a lot of force. Now, I may be able to design around this issue and strengthen the area. I can also design the hinge ears to be a separate component that bolts to the lid. This technically could make that area stronger, and makes any hinge replacement significantly easier; at the expense of simplicity and ease of assembly.  

So as you can see, at the moment, I'm doing testing mainly on hinges. My goal is to choose the best solution for this device. Once I can choose what torque hinge is the 'best' I will switch to really refining the mounting solution to address any potential issues and finalize the design. I'm also considering mocking up a little test bench to torture test the design. Basically a mechanical device that will cycle the lid open and close hundreds of times to ensure the design is robust enough and note any failures.

After that, depending how long the hinge takes and the state of the ZeroWriter when I finish, I will jump over to the cable pass-through mechanism and really ensure that is refined. And I've been pondering ideas for lid closure clasps (outside of simple magnets) and I may start tinkering with designs when I need a little mental break from hinges.

05/20/25

This is sort of a continuation of me now abandoned E-ink writer system. I'm now piggybacking off of the upcoming ZeroWriter Ink. Given the immense progress that team has made on this device, it makes more sense.

The open source data, including the all important CAD files, are yet to be released. However there are still plenty of components I can work on in the meantime.

Here is a broad overview of what my focus is. I'll post from time to time with little tid-bits and updates. 

Hinge Assembly:

Working from my earlier work, I've been tinkering with the design of the hinge system. This, by and large, is the most important part to get right. There are a couple of considerations:

1. Reliability and robustness after many cycles. The design needs to ensure that hinges don't snap off after prolong use. Being 3D printed, it is necessary to consider things like layer direction, material thickness, heat insert stability, and etc.

2. Smooth operation and angle holding. Essentially, the screen needs to be easily swung open and hold at a variety of angles. Like before, I'm working a couple types of friction hinges to achieve that; more on those hinges later.

3.  User friendly assembly. I'm attempting to make the printing and assembly processes as easy as possible to achieve the lowest technical knowledge threshold needed to put together. 

4. Ease of part replacement. In the inevitable event of something accidently breaking, things need to be fairly easy to repair. This essentially eliminates the use of permanent fixing, like glue or press fit components.

So lets talk about the design. I'm waiting on some friction hinges from China to test additional designs. There are a lot of different shapes and sizes of these things, so it's important that I choose the best one for this application. Right now, I'm focused primarily on three different types. 

1. Embedded barrel: Thus far, I've had success utilizing this type. The mechanical mounting system may offer better long term stability than a press in style. However there are some concerns so far that need to be addressed. Namely regarding plastic fatigue around heat inserts and the cavity the hinge fits into. I'm also wondering if the torque value (0.1Nm) is still too high, but I need to test in a full size unit to be sure. I've printed up some PoC, and after a few revisions I found the design worked quite well. Operation is smooth and alignment is good. I was able to achieve an opening angle of about 130 degrees.

2. Press-fit barrel:  Similar concept to the above, but instead of mount with screws and heat inserts, it presses into a keyed slot. I still need to print up a PoC to see if this is a better option. If I can manage to dial in the tolerances, this may prove to be more reliable than screw mounting. Assuming, that the keyed slot doesn't overly loosen after prolong use. This style also offers a simpler installation.

3. Southco ST-4A-3S-33: Another press fit design. The main differences being that it's actually somewhat available locally (USA) and it has an unusually low torque value (meant for small medical devices)(0.034Nm). This may be a good alternative if the 0.1Nm proves too stiff.

Cable Passthrough
Another important consideration is how the cabling will pass between the two halves. Not only does the design need to protect those wires, but also reduce as much wire fatigue as possible. Also, unique to this design, I want to design it so the user can assemble everything and pass wiring through without having to chop and resolder anything. I have a basic PoC, that works well fairly well. It still needs refinement in the 'knuckle' design to eliminate any rotational friction. Right now, its free floating, but I may need to design it as a pin style hinge.

I don't yet know what the cable length will be on the finished Zerowriter. But I'm operating based on the worst case scenario, which is, it won't be long enough. So I've started working on extension cable / PCB. Due to the connector size, It may be necessary to break out the cable into multiple or a single smaller male plug so that ensure pass-through hole can be as small as possible. 

Lid Closure Latch System
Due to the nature of friction hinges, the lid does close completely shut. Originally I was simply going to use magnetics (like a typical laptop) to snap the lid shut. However I'm toying with the idea of using a mechanical latching or strap; like those straps on old books. Other than seemingly being fun to design and adding a unique visual flair, it does technically offer a much more reliable system that's far easier to manufacture. It also offers potential for end users to customize and add a little individuality to their unit.

I'm also investigating the use of a other purely mechanical systems, like push latches

Enclosure Design
Until CAD files are released, I'm limited on what I can do in regards to a final enclosure design. I do know the finished designs will require a print bed of <275mm. This presents a unique problem, as most commercial printers (Bambu, Prusa, etc) have max print sizes of 254mm. This means that the enclosure halves may be required to be printed in sections. With that in mind, I've been pondering ways to bring those sections together so that it looks good, is secure, and maintains proper alignment. I've decided to wait to do real design leg work until I know what I'll dealing with dimensionally-wise.

I'm also thinking about visual design too. How it looks and feels and the practical application (ie: does it slip in and out of a bag easily, are there areas where dirt/grime accumulate, etc). Again, a lot of design work is really dependent on the specifics of the finished ZeroWriter design/dimensions. So most the concepts I post are just that, a broad idea based on educated guesses. I imagine there will be many many iterations after the CAD files are released, and it'll look radically different in it's final form.