Falk Schönfeld

Flatpak Raspberry Pi case

2026-06-11T00:00:00Z

I've been seeing a lot of compliant designs for 3D printing over the years and when I had need for a case for a RaspberryPi based test computer (RasPi + cooler + relay board + adc board), I took the chance to play around with a design idea which had been bouncing in my mind for a while

Model before printing

Flattened case after printing

Rear showing of the bending marks

Open front for cable access

What did I learn?

Printing all sides flat means all of them are well aligned and stable. I could probably get away with even less wall thickness (currently 2mm, could probably be 1.6mm).

0.4 mm hinge thickness is plenty.

A previous version with a more complicated design chamfered with 45° on all inner edges of all 6 sides for joining the outsides did come together so well. It also had a more complicated pin based design to hold the parts together, which was way more hassle than designing the outer ends as lids.

I really like the screw attachment points interrupting the flexible joint, it gives the entire thing a really well-thought through air. Even though I only added them as an afterthought.

Black is probably the worst color to print such a design. Bending the corners 90° will visibly discolor the PLA. Buuut ... since its black, Edding can and will easily fix it. The problem does not visibly appear at all with white PLA though.

Bendy printer bed levelling with kapton tape

2024-02-12T00:00:00Z

Uneven beds are a staple of 3D printing and leveling them can be an artform in itself to ensure every print sticks. But what do you do when your bed is not uneven, but curvy?

I've written about the Voron I built before. Among other things, Vorons are equipped with an inductive probe to allow leveling both the gantry (the x and y assembly hung up on 4 steppers in z direction) and to create height maps of the print bed for auto leveling. This is no Voron specific feature but quite common in the 3D Printer world.

Auto leveling basically means that the printer takes the shape of the bed into consideration. If a part of the bed is higher, the printer offsets its Z-position in those x/y coordinates to account for it and avoid squishing the extruded plastic too much or too little. However, it would be even better if the bed isn't uneven in the first place.

Klipper, the firmware running on the printer, allows defining the grid which is used to create the mesh of probe points to approximate the bed shape. I chose a 5x5 grid for more detailed resolution. Unfortunately, my bed looked closer to a potato flip than to a flat surface than I had hoped. Luckily, the graphical depiction exaggerates the real values and overall there is only a .2mm difference. Still, about as thick as a single layer of the print.

(It is important to note that this could also be due to a bend y-axis on a Voron, but I do not think this is the case on my printer, since I rotated the beam and the problem remained.)

At some point I had a bit of a mad idea: the Voron has a PEI plate for easier print removal. This means the bed is basically a sandwich made of the following layers (top to buttom):

PEI plate (thin bendy metal sheet covered with PEI surface)
magnet sticker plate
aluminum plate (heated body)
heater pcb sticker

All stickers stick to the aluminum plate. That means the PEI plate is only held on by magnetic force and gravity. It is easily removable and flexible enough to adapt to changes in the underlying surface to a certain degree.

So theoretically it should be possible to even out my potato flip bed shape by placing something thin underneath the sagging parts. Unfortunately, it needs to be both very thin and heat resistant, since the bed is regularly heated up to 110°C.

I chewed on this for a while but then remembered I had a roll of kapton tape lying around. Kapton is a polymide film which is very resistant in a wide range of temperatures and therefore used not just in 3D printing but many applications up to coating NASA's space shuttle wires according to wikipedia:

wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires.

Huh, maybe I should not use it to coat wires then. Good thing I only intend to use it as a standoff.

I basically used my bed mesh feature from mainsail as a guide. Since I had 5x5 probe points, I knew where to place each strip of tape on the bed. While the tape was far from wide enough to cover the entire surface, I figured I could just lay down some tracks and the bendy PEI would cover the gaps in between nicely.

So it was just a matter of iterating layers until the bed got flatter. Kapton film is 0.03mm thick and the adhesive is supposed to be 0.04mm, so each layer should adjust by about 0.07mm. Since I can only adjust upward, I started with a single line in the most saggy part in the middle.

Initial height map

Slowly getting better

This is usable

Overview of dwindling height differences

That brought me to a W shape. So I stuck another layer in each of the minima of the W and things got way more even.On I got lucky that my bed is mostly bend in X-direction, so I laid the tape in Y-direction only affect local parts of the curve.

Once the X-direction looked satisfyingly, I started correcting Y-direction. Now I needed to partition the tapes so the overlap with the others did not mess up existing adjustments.

After I reached a satisfying level, I adjusted my Z-Offset with a few test prints.

Current Kapton shims (and remains of former prints which I should really clean up)

Overall, things stick better to the plate now than they did before and the fix is non-invasive, durable and cheap. I've seen Kapton used as a print surface before this, but not as a leveling help. Although a google search suggests similar attempts have been made. I can only recommend trying the approach.

Getting a grip on longboarding

2024-02-11T00:00:00Z

I recently switched jobs and with a shorter commute skating became a viable alternative to cycling, so I browsed the web to get an overview of longboards in general and bought a used one for cheap on ebay.

Landyachtz drophammer, only marred by inexperienced users like me

Learning to skate has been a pleasant experience so far, but this is not what this post is about. My underlying motivation was that once I am able to longboard safely, I can take it with me on the subway and other public transport as a range extender, even in rush hour.

And while the board is easy to grip on either side to carry, I saw a couple of other boards online which had a cutout grip in the middle. Since I got my board cheaply anyway, I saw no reason not to retrofit one onto my board.

The process was pretty simple:

tape off everything on the board. If you have nice deck art, ensure that your grip won't fall into a nice part of the artwork
draw a line parallel to the board side on the tape as a guideline
grab the right diameter of the hole saw for a comfortable fit for my sausage fingers and guesstimate a good offset between the holes. The holes should overlap but not too much. In my case 2cm between centers turned out to be a good distance. Mark 4 spots for drilling.
ensure the board lays flat on some stable offsets and doesn't move while drilling. Also add a cardboard box or similar to catch saw dust beneath where you want to drill
predrill the holes with a 4mm wood bit
predrill about halfway through the wood from one side with the hole saw. This breaks the surface more cleanly than if you drill through from the other side.
If you predrill all four holes at once, you only need to flip the board once.
flip the board
drill all the way through with the hole saw

Drilling through the board

sand off any sharp edges between the holes of the hole saw
sand until smooth, from coarse to fine grit. Wrapping the sandpaper around an Edding proved to be very comfortable to reach into the hole

Testing the fit

Sanding the grip to make it more comfortable. I wrapped the sandpaper around an edding to get in better.

oil the sawn edges. Use a small piece cut from a sponge held by self closing soldering tweezers to feel real professional while doing so without getting your hands dirty.
sand again to get rid of the grain which stood up
oil again
use a clean part of the sponge to spread the oil which leaked into the grip tape around so there is a smooth transition between the hole and the rest

Finished board

The grip is comfortable to hold and so far I haven't noticed any difference in the handling of the board, so it was worth it in my opinion. Since Landyachtz have a pretty wide logo up top, the Z got cut away. I just blacked it out entirely and now have a Landyacht instead. Let's see if anyone will spot the difference in the wild.

FOCK (Falk's overstaggered Corne Keyboard) - Designing my own mechanical keyboard

2023-06-13T00:00:00Z

After my former dives into keyboards - including the Ergodox EZ, the gboards Buzzkill, and a CRKBD, I decided I wanted something more personal.

After ~~procrastinating hard~~ collecting my thoughts and experiences for a while, I happened to see one of Ben Valleck's videos about designing personal keyboards. (He has since made another more detailed one.)

This made me discover MrZealot's (Bán Dénes) ergogen keyboard generator, which (in their words):

aims to provide a common configuration format to describe ergonomic 2D layouts and generate automatic plates, cases, as well as un-routed PCBs for them.

This got the gears in my head turning again. It took me a while - until my girlfriend caught Covid19 and I had to abandon all my weekend plans to be specific - to turn them into an actual design.

Initial design criteria

Everybody wants something different when it comes to custom hardware - which is kind of the point. I wanted the following things:

Split design: I don't care about pressure points and clackyness as about general hand position.
USB-C: My XPS 13 and my phone only have USB-C, so why bother with anything else? Includes the connection between the halves.
Number row: I plan to reduce my use of this, but this was the #1 feature I regularly missed on the CRKBD, especially when I was tired and had to enter passwords.
3+ thumb keys per side

First layout test - initially I just wanted a CRKBD with more stagger

Getting into ergogen

It took me a while of playing around with ergogen to get used to all the commands and possibilities. But after aforementioned interruption happened, I decided to commit and churned out a halfway usable design to refine in Kicad over the weekend.

Layout shape generated by ergogen

Ergogen output in KiCAD

Version 0

I used printouts and .stl files generated by ergogen to verify that my designed layout actually felt good. I even fitted keys into a top plate to see how phantom typing felt. This process is something which I would recommend to anybody trying to go for a new layout.

Iteration process: from 1:1 paper cutouts to 3D printed mockups to hold keys to PCBs to populated, working device

Version 1

With the layout sorted, I was ready for the actual electrical design - or so I thought. I made a couple of mistakes I would like to highlight to ensure others don't repeat them needlessly:

Unfortunate footprint alignment per key
My initial version of a "per switch footprint group" had the diode placed in a way that it nearly blocked all possible connection methods. This slowed down routing enormously.
Unfortunate matrix connections
With keyboards, you often use a keyboard matrix. This means each row and column is connected to a pin on the microcontroller. I managed to intuitively choose the most annoying way to assign them: At first, my number row was connected to the lowest of the chosen pins on the microcontroller, my bottom row to the highest. Similarly all other rows and columns fell in line to ensure every single connection basically had to cross all others as often as possible.

This became a problem since I did not realize it right away. Default Ergogen is only meant to place the switches and components and leave routing to Kicad.

Since I first routed all nets within the keyboard matrix in itself and only then tried to connect rows and columns to the microcontroller, I realized this way too late. When I did, I tried to change controller pin nets to a more useful order in Kicad rather than recompiling the ergogen, since I did not want to redo the matrix routing.

Bad routing fixes and ignored KiCAD warnings
This led to my final error in the first iteration: somehow in this process I must have swapped front and back layer for my routing. Since it was already past midnight and I wanted to get this done on that very weekend, I ignored some KiCAD warnings, which would have prevented this.

So when I got my first round of PCBs and wanted to solder the first parts, I took a close look and saw that none of the pads had any connections. And since the PCBs were flippable, I could see traces leading into nowhere, or more precisely, to where the pads were on the back side.

Well, 30€ well spend on learning one way how not to do it.

Look closely and the distance between pads and traces will show the difference between theory and practice.

Version 2

After that setback, I got the next motivation kick during Virus Wars - Episode 2: Corona strikes back. This time I caught it, isolated in home office and had spare time again. I fixed all the issues I encountered in the first round, improved my footprints and replaced TRRS with USB-C connectors between the halves. I also got carried away and started routing in ergogen too.

Footprints with traces in ergogen
With different tilting angles between the columns this really helped getting orderly, similar traces in all key footprints. A reversible footprint a footprint group for a key with a diode slot has some 8 to 10 traces at least. With my 6x4+4 keys, that is 224 to 280 manual traces which you save, which is worth the effort in my book.
All the traces in ergogen
But at that point I had a murder headache from the virus and couldn't sleep anyway - so naturally I distracted myself by routing ALL the traces in ergogen. Not sure I would really recommend that. My recollection of the experience is hazy, but I think I would rather go for an auto-generated routing for the second half like this project the next time round. Still, it looks cool and does the job, so it is a win in my book.

Assembly

After waiting another week I got the PCBs.

By the time I got this far I had gotten Nice!Nanos V2, which work with ZMK, a bluetooth focused, complete rewrite of the QMK framework. ProMicros cost less than 25% of them, so I wanted the USB-C as a backup for cheaper builds, but I haven't gotten around to actually using it.

Marking the top on flippable PCBs prevents many mistakes...

Building a keyboard is the second-best part of the process, only beaten by seeing it working as intended.

Adding clickyness

Top and bottom side just after assembly, no stands or battery yet

I did solder on a set of USB-C ports onto one set of boards, but I never used them for the connection between the halves, bluetooth just worked flawlessly. I just wanted to route I2C across the USB-C data pins (which I know is an abuse, but I have a lot of USB-C cables so why not), but I haven't gotten much further than checking connectivity and shorts.

Hotswap sockets

My current layout uses home row mods. Sometimes some held keys would not register as held but trigger several times instead, as if the switch was not properly debounced. That was easily fixed by replacing the switch, so it is most certainly a mechanical issue.

Another time (actually the second time I used them at work), I spilled hot chocolate over the board. Removing the switches made cleanup so much better.

Tenting

I first used some standoffs from leftover projects with rubber nubs at the end for tenting. That lasted me a couple of months at work, since the keeb was basically instantly ready to use as a daily driver.

I have since revisited the openscad part of ergogen and am currently in the process of building a nicer stand. That will probably be another post though.

Batteries

I ordered the batteries and plugs on aliexpress and they arrived after two months of almost daily keyboard use on USB. Losing the tethers was really refreshing and the charge lasts me 1-2 weeks.

Prototype of a 3D-printed tenting leg

Hotswap sockets and battery mounted with 3M double sided tape

It's the small things which make the build really comfortable.

Fancy keycaps

Keycaps are a rabbit hole in their own right and part of my reason for choosing Kailh low profile switches is that the rabbit hole does not go as deep here yet as it goes for Cherry style stems. Nonetheless, when the MKB Legend set was released, I got two sets and they really helped tie the build together visually and I don't regret a cent spent on them. (BTW, I ordered most of the more specific parts on splitkb.com, and the rest on ebay and aliexpress.)

So many options

Overall impression

It feels great to design and build something and use it daily. The ergonomics are good. In my opinion the split is the biggest advantage, followed by the thumb cluster and then orthogonal layout. Of course, the fact that the column stagger and tilt is customized to my hands makes them great for me, but horrible for most others. Since the pinky columns is shifted almost one key unit against the ring finger column, I need to ensure that the halves are rotated enough against each other so that I instinctively reach for the right keys. But that is the most comfortable position anyway. Home row mods are nice, but mainly a gimmick for me, since I try to avoid making writing the primary part of my job.

The two boards which I assembled side by side

The next keyboard iteration will get footprint an easily visible RGB led to symbolize layer changes and layout changes. I can do without, but it would help sometimes.

Overall, a great experience. With two sets fabricated, and all parts for a 3rd set still in storage, the price per keyboard set is way lower than a Kinesis freestyle, and it fits my wishes, layout preferences, aesthetic and hand size way better. If you have the time, I can therefore recommend spending it on designing your own keyboard.

Big thanks to the ZMK team, Ben Valleck and MrZealot! Without their work, it would have taken me way longer to get this completed.

All ergogen files for the FOCK can be found on my github, as well as my layout for it. Should you decide to build your own, send me a picture!

Thirst Aid Station

2023-06-05T00:00:00Z

Last Christmas my brother moved and I got the idea to get him a wall mounted bottle opener for his new flat. I found a nice bear head shaped opener online and decided to build the wooden mounting plate myself.

Unfortunately, DHL had something to say about that. I got the components eventually, just not in time for Christmas. So this idea lay around until his birthday drew near.

Basically I just drew inspiration from some pics online for the image. After sketching it out on blue tape, I engraved it with a rotary tool, but it looked mediocre. Next try was to burn the outlines in with an old soldering iron, which worked way better.

A leftover 20kg magnet was epoxied into the lower end of the wooden plate to catch the bottle caps.

Engraving the design

I then masked the area around the cross in the middle and stained it with some teak wood stainer which I had from other projects.

Staining the cross

It turned out suboptimal since it spilled below the masking tape in some areas. A bit of scratching with a cutter knife fixed that.

... and a bit around it

After that is was mainly a question of sanding and oiling the entire thing.

Review: CRKBD Corne - Getting started with split keyboards II

2022-10-09T00:00:00Z

You might remember my previous journey into split keyboards, where I got a Ergodox EZ from a friend to try and only kind of liked it. After that, I got a BuzzSaw kit from gHeavy Industries, which I liked, but never quite got to work well enough to be a daily driver. Maybe that's a blog post for another day, when I finally fix it up.

Then, in the height of Covid, I was browing r/MechanicalKeyboards and came across an IC (Interest Request) for a yellow Corne keyboard from a Spanish guy. This post is about my experiences building, modding and using it.

The iconic Corne shot, this time in yellow. Notice the - way to short - cable connecting it to my laptop, contrasted by the - way too long - TRRS cable connecting the halves

For those of you who don't know the IC term, here's a short rundown: Buying exotic keyboards can often only be done via dedicated resellers or by directly ordering PCBs and electric components yourself. JLCPCB, PCBWay and most other manufacturers offer a minimum order volume of 5 PCBs, which means you order at least 2.5 split keyboards. Buying components in bulk is cheaper, too. Now consider that one of these keyboards usually costs at least 80-100$ with switches, and that sky is the limit for the upper end of the price range. It is therefore no surprise that people try to sell off their surplus. This is done in so-called Group Buys (GBs), and before one is started, an Interest Request (IC) gauges the level of interest in the community to join one.

The Corne is basically the 40% split keyboard out there. If you see a picture of a fancy, flat, minimal, split keyboard, 90% of the time it seems to be the Corne. So it is a well-known and relatively wide-spread design. I decided to get one because it was easier than designing my own from scratch, closer to what I imagined I wanted after the Ergodox and BuzzSaw, and was a proven design.

The Group Buy phase

After filling the IC, the GB started. These tend to take forever. Initial delivery times were estimated in a couple of months, but with some components arriving way later at the organizer, it quickly rose to almost a year. That is completely normal, even to be expected, and way lower than the GB durations for some GMMK keycap sets.

As a result, the rush you feel when you finally get the packet is way bigger, so I guess it is alright. Apart from the delay, the GB went nicely, the GB's organizer kept us updated and was motivated. Everything was as it should be, and after some wait I finally had my kit my hands.

DIY Corne kit: PCBs wrapped in newspaper from transport. Key switches and keycaps are bought separately, so they aren't shown here.

The build

Test fit before assembly. I was not sure if the top layer PCB went below the switches (right side) or above (left side).

Assembling a Corne is not that hard, if you have a bit of soldering skills. However, it does help if you read the instructions. Like, all the instructions. And maybe the ones for different variants and in Japanese too. The pictures help as well :D

Anyway. I assembled everything and some of my LEDs did not work. Turns out, the LEDs don't like heat, and if you solder them with 350°C like I did, you're gonna have a bad time. The part about lowering your soldering iron's temperature for them was only present in one of the instruction variants I read later on. Luckily it is easy to debug, and after ordering another 200 or so of the same LEDs for 5$, I began replacing LEDs in the chain until everything worked, which was an experience in itself, but doable.

LEDs not working. You should check before soldering in your switches.

The LEDs are still fairly easy to replace. Just put slight pressure on the LED with some thin object on the back side, heat up the solder connections, and let gravity push it out. Be careful with the pressure, you do not want to rip out the traces.

Setup to put pressure on LED to lift it out

Halfway removed LED

Function check after replacing LEDs

LEDs with switches

I ordered some OLED screens with it, knowing I would not really need them but wanting to try them for the 8$ price tag anyway.

The programming

The CRKBD is powered by two ProMicro ATmega32u4 controllers (one in each half) running QMK. I started off with a fairly standard QWERTY layout, then added some LED control, and special keys on a layer. Basically just enough to get me started. Then comes the point where you force yourself to use it, and change everything which feels like a bother until it feels better.

Coding time

I added secondary Workman layout with a button to change between the two. That allowed me to learn the workman layout easily. Then I read about mod-tab behaviour, my favourite feature of QMK and similar keyboard software. I delved deeper and finally added some home row mods.

I played with the LED behaviour, but figured out that their light mostly annoyed me, so I compiled without support for them to ensure they were always off. I also added some cyberpunk animations and WPM counters to the OLEDs, but again, similar to the LEDs, I don't look at my keyboard while typing, and it only annoyed me.

The actual usage

I managed to build the keyboard during my master's thesis, probably the time in my life with the most amount of daily typing in my entire life. Procrastination trying to touch type with the keyboard and various typing training websites (keybr.com, typelit.io, speedcoder.net, etc.) ran rampart and it is safe to say I typed rather to much than too little on it. And it was nice. I adapted easily to the column stagger and never wanted to look back.

It just feels nice to have all keys closer. I love the three thumb keys. I love space on my right thumb and backspace on my left one. It just feels natural. Mod-Tab behaviour (where quickly tabbing a key might type a space, but holding it down might activate shift) is a great feature and one of my favourite things about the keyboard. Home row mods took some getting used to but were absolutely worth it.

Having the option to quickly change to workman made me learn the layout to the point where I can reach ~65 WPM on most days. It works better than QWERTY and I really like it. However, I have an i3 and VIM setup and use both extensively. That is fine while you only work on your machine, and great while you are at home. The moment I went back to university and touched uncustomized hardware, it all went to shit and my muscle memory worked against me, which is a bummer in these heavily optimized environments. I also noticed that my bottleneck is hardly ever my typing speed but usually my thinking speed, so I mostly stayed with QWERTY except for pure text.

I missed the number row and never got around to making a dedicated replacement layer. Maybe I am not quite ready for that yet. Maybe I will be at some point in the future. Only time will tell.

At some point I found the Miryoku layout and began stealing inspiration from it. At one point I even said so on a reddit thread and the maintainer motivated me to do so. I suggest you do the same, it has some neat tricks.

Most of that is just standard QMK stuff, and not specific to Corne or split keyboards. The hand positioning did turn out to be very relaxing though, much more so than my standard keyboards.

Mounting the keyboard

At some point I saw a reddit post where somebody used two camera mounts to attach the halves to the armrests of his chair. I ordered the same ones and printed some attachment points for my keebs. That started the most chill writing phase of my entire thesis. The feeling of leaning back in an office chair, hands comfortably on your armrests, and typing away is premium. It was the moment I knew the entire process was worth it.

Camera clamp arm on Corne

For just 30€ extra I got the feeling of being a space ship captain. Best impulse buy ever

I also designed an ultra-low, adjustable tenting stand for it, but that never got as much use.

I tried, but I could not get it any flatter

Height adjustable in 5mm steps

I really like the look, but it is not as good or stable as the armrest clamps

Review

However, not all was well:

My LEDs kept getting bad connections. No amount of fiddling seemed to solve it forever.
I missed the number row.
Carrying the keyboard around to work is tedious. That could be solved by a second keyboard.
I need an adapter for USB-C for my laptop. That could be solved by longer USB-C to micro USB cables. Or by going entirely cable-free via bluetooth.
The connection between the keyboard halves is with a TRRS cable, which tends to get in the way and of which I only have a single one. If you unplug and replug it while the keyboard is on, you short some circuits and might fry the board. USB-C connectors might solve this, or going bluetooth might.
Most of all, the keyboard matrix is not staggered enough for my liking. I just kept reaching for keys in places where they weren't.

Overall, the CRKBD is a great keyboard and hits a sweet spot in many things.

Its place as a prominent split keyboard is well-earned and justified in my opinion. For now, my corne gets passed around to interested friends, to show off the hobby and get more people interested in building their own keyboards.

But I know now that I want something different at some point, something even more personal, and something to try my kicad skills on. But that is a story for another post.

Restoring an old road bike

2022-07-25T00:00:00Z

I've been riding bikes everywhere I can most of my life. To school, to university, to work, to festivals. Recently I noticed my old trail bike had a crack below the seatbelt clamp. Combined with some other wear and tear it got over several thousand kilometers of abuse it got me started on thinking about a possible replacement.

For a new bike I did want to try and get a road bike, because while I did the look and feel of heavy suspension, asphalt is what I ride on 90% of the time. I already owned and rode road bikes twice before, when I stayed in Sydney and Seattle for a while. Both times I got them cheap on gumtree or ebay, restored a few parts, rode them while I was there, and sold them at a higher price.

I thought a while about getting a new road bike, but the price tag of the ones I really liked were way higher than what I was willing to pay. Also, if I look at new stuff, I always tend to gravitate towards wanting to buy much more fancy shit than I need, which honestly doesn't help. So after a while I just stopped looking.

However, when I was looking for something entirely different on ebay, an ad for an old road bike just around the corner caught my attention, and after a quick search around I got in touch with the vendor. While I do always fear that I am offered a stolen bike, but in this case the bike looked like it spent the last decades in a garage. While that does not ensure it is not stolen in any way, at least it doesn't mean it wasn't taken from anyone using it. After I ensured that it ran reasonably well and haggled a bit, then pushed it home.

Initial state of the bike

Initial state of the bike

So, what did I get to work with? As far as I can tell it is a Peugeot PH8/D, as can be found in this old catalogue page from 1981. The equipment was mostly the same, minus the hand pump, handlebar tape and the saddle, which had been switched out for a different one. When I tested the bike before buying it, I noticed that the wheels turned nicely, which is always a good sign, and the frame did not have any obvious dents or signs of use. Apart from the occasional spot of rust there was nothing off putting. The derailleurs worked nicely, although they were not well adjusted. The tubes for the pulleys and the pulleys themselves showed their age. Instead of handlebar tape, the handle had been wrapped in electrical tape. The tires still seemed be original, a small crack from going brittle with age on the sidewalls but otherwise great. The valves were a dutch one and a french one, which had broken off. But they did not have any bends or much wobble in them, which was nice. I try to get quick release mechanisms on my bikes because I often manage to flatten tires (the downside of living in Munich, where public drinking is allowed and you often find broken beer bottles lying around), but don't want to carry wrenches everywhere. To my surprise, the bike had something similar: Wing nuts. I honestly had never seen them on a bike before, but decided that this was part of the experience. The center pull brakes looked ok, but needed adjustment and new pulleys. The dynamo seemed fine but the lights did not turn on.

Getting roadworthy

Whatever you try to fix on your bike, youtube is a great resource. Since I had never replaced pulleys, only readjusted them, I watched videos on that, and on on center pull brakes. The two channels I kept returning to were Park Tools, which of course show off their own fancy products, but offer really clear instructions on fixing anything, and RJ the Bike Guy. I would probably start with park tools, since their video lists are really structured: You can watch an overview video on figuring out what the component you are trying to fix is called, and which subtype you have (e.g. center pull brakes, side pull brake, dual pivot brake, etc.), and then take the link to that specific video. Once you have watched that and still have further questions, you know exactly what keywords to google to get the answers.

Prepared like that I browsed a couple of websites to find the parts I was looking for. My go to website in Germany is bike-components.de.

Repair stand

While thinking things through, I also realized I could not just turn the new bike upside down and place it on saddle and handlebar, because the brake pulleys go straight upwards and it would bend them. So I searched around and decided to get a foldable bike repair stand. I did lots of bike repair without one over the years, and friends let me try theirs once before. While you can do almost everything without, it is much nicer to do with a stand. This one works really well, it is super stable and has nice pads on the feet which prevent scratching the floor it stands on, so I just overhauled my bike in my living room during rainy days. It made all the pulleys and brakes well accessible and I could turn the wheels to test everything without having to lift the bike every time. It also doesn't take too much space in my cellar while not in use.

Pulleys and bowden tensioning tool

I bought replacement sets for the pulleys for both brakes and shifters with red tube. For some reason that was the hardest decision, because the metallic red of the bike was already so flashy and I wasn't sure if I wanted to make it even flashier (before it had black tubes). I know from experience that flashy bikes tend to change owner fast, often against the will of the current owner. But then I decided that the bike already looked fancy anyway, so I decided to get the red tube anyway, and it really looks great on the bike.

I also bought a bowden tensioner tool. I have tensioned brakes before without one and always found it a huge pain to get right. As the Park Tool video showed off how easy it was with their tool, I decided to try it (with a cheaper knockoff). I really liked using it and would recommend getting one if you have to replace bike pulleys. In my opinion brakes are the most important part of a bike to maintain. And perfectly adjusted brakes can save you way more than 15 bucks when you ride in a city with dangerous drivers every day. Do try to get one with a ratchet mechanism though. Overall changing the pulleys was super easy following the video tutorials, and cheap to do. Each replacement set set me back 15 bucks, and the tensioner 15 more.

Brake adjustment

While adjusting the brakes I also completely took apart the brakes, cleaned off the rust using a dremel and a sanding tool, polished them with some oil to delay further rust and reassembled them. I took care not to oil the brake pads of course. Somebody had obviously tried to do that before, and had gotten the order of washers, adjustment rings and nuts wrong. Once again, the brake is the most important part of the bike. It stops you from rolling into moving traffic, running into car doors opening in front of you or running over pedestrians which cross your lane without looking. Especially if you buy a used bike, please check yours to make sure the guy before you knew what they were doing.

Unlocking the bike

The bike also had an old Abus frame lock. It was locked in the open position. I did not get the key - in fact I didn't even notice it while buying the bike. While cumbersome, it was possible to unscrew the attaching bolt when the rear wheel was detached, so I did just that.

Shedding some light on the process

I also opened both front and rear light and took a look at the bulbs. I did not have high hopes, but both looked fine and after polishing the contacts a bit, both came back alive without any further work. I still have 3 proper spare light bulbs from other bikes, after that I will probably replace them with LEDs to get a bit more power. But for now having working lights ensures I always comply to road regulations and I can easily add a battery powered front light for dark nights.

Replacing the inner tubes

While I expected this to be the easiest, I ran in a lot of trouble here. First, I ordered the wrong diameter tubes, too small, due to the fact that the lettering on the tire was so worn that I did not notice it. Then I lost my French valve adapter and hat to buy a new one, which I proceeded to lose 2 days later. At least I had pumped my new tires up first.

The first test ride

Still with the wrong diameter tubes I did the first test ride. My bike was still missing handlebar tape, but it rolled nicely. Until it didn't, some 2km down the road. The rear axle, held by two wing nuts, had slipped. Old bikes have a horizontal mounting slit for the axle, and if the wing nut is lose, the rear wheel will slip and grind against the frame. I readjusted the wheel, and tried tightening the nuts further by hand. But another 2km later the spectacle repeated itself. I did this a couple of times, and once the axle slipped in the middle of a crossroad and I had to quickly hop off and carry the bike off the road while cars were moving around me. Can't recommend. After about 10km the (wrongly sized) inner tube of my rear wheel gave up and I left the bike close to a subway which I took to work.

The second round of repair

After I carried my bike back home I began raiding local bike shops for the rest of the parts. I took the wing nuts to a bike shop and got proper nuts which I could tighten further. I also got inner liners for the tires since those had rotted away over the years. The shop guy also helped me spot the proper inner tube diameter on my tire, and I decided to go for car valves to skip the adapter. The valve stem was too wide for my wheel, but a drill solved that problem once and for all (yeah, I know, that is a brutal solution to this problem, but this project was about making this bike safe and fun to ride first, and only to keep the original look second).

I also got handlebar tape. Previously I had looked at West Biking road bike gradient handlebar tape but I wanted my bike finished now, so I just took some nice red handlebar tape available at the store. Maybe when I need to replace it in the future. Once again I argued internally between flashy red and somber, dirt-resistant black, and once more flashyness won. After all, this bike wasn't going to look bad just because one part was black.

Back at home I tore off the electrical tape of the handlebar, which revealed quite the large rust spot underneath. The tape looked years old, so it was probably not the vendor who put it there but rather the original owner. Another thing which will go on the check lists for future purchases. Luckily the rust was only on the surface, so I cleaned it up somewhat and oiled the spot against further rust. Then I adjusted the brake handle positions and wrapped the entire thing. Park tools also has a great video on that.

Lastly I adjusted the saddle upwards a bit.

Cottered cranks

After I put in some kilometers, I noticed that the bottom bracket started clicking after riding for a while. I took a good hard look at the crankset and discovered they are cottered cranks. This is one of the areas were I am really happy that the industry has moved on. Once again, RJ has a great video for maintenance, and cotter pins are easy to buy as soon as you know what to google for. I disassembled the entire bottom bracket, cleaned everything, replaced grease and ball bearings and put it back together. Then it was only a matter of getting the damn cotter pins to hold fast, which only took me ~~countless hours of frustration and several testrides where they started slipping halfway to my destination~~ a bit of tinkering. Similar to RJ, the best solution I found was to get a piece of 2x4 wood as support while hammering the pin in. I additionally drilled a hole large enough to put it directly under pin so it is supported on all sides.

Custom Cotter Crank Support Tool - Get yours now for only 99.99€

More testing and conclusion

Current state of the bike

I've since ridden the bike around 400km before I changed work and my commute necessitated a trail bike again. It is well roadworthy, and I often use it on short rides or when I blow a tire on the other bike. But riding a bike this old always means maintaining it. Just the other day another biker told me "Your chain could use a drop of oil" and when I laughed and told him it isn't the only part of the bike which could use some, he added "But you are going pretty dang fast for that old thing." So yeah, the work is never done.

Also, the stretchy fabric on the saddle seems kind of worn, so I will probably pick up a cheap replacement at some point. Then again, my other bike has cracks in the leather of its saddle since years, so maybe not that fast.

In a city like Munich with flat streets and nice bike lanes this bike rules. While it is not a true racing bike and has some excess weight like mud guards, lights and rear pannier, it is perfect for my commute when I need to get to public transport. It is much lighter than my other bike and handles a lot differently, and is very fun to ride.

I also bought it during Corona at a time where the rest of the bike market got very sparse, apparently due to high demand and low supply. I didn't notice that, and scored a relatively cheap bike. Overall, I paid around 250€ on the bike, and another 100€ on tools which I have since used on other bikes as well. Of course I put a couple of hours of work into it instead, but I had fun doing it.

I'm also proud that I kept a bike of the landfill and gave this antique new life. Also, if I had bought a new bike instead, I would have gone down the rabbit hole of which gear I want vs which gear I need, which would have taken a lot more time than I spent repairing this one and probably bitten a larger hole into my wallet as well. This bike has lived for almost 4 decades, and I'm sure it will live another one or two at least. Sure it will need some spare parts, but since the mechanics are simple, it will be easy to find them.

For me it is a "luxury" bike and will only get used when I know my route will not go off the road. Luckily, my daily commute often fits the bill.

I also feel like I wouldn't want to leave it locked in the city for too long since it looks too nice. While I haven't had a bike stolen here, friends and family have. However, if it comes to that, losing 250€ is a loss I can survive.

If I were to get another road bike, I would look for the following things:

No cottered cranks
Quick release skewers
Brake handles with brake lines running alongside the handlebar, not going straight upwards
No sections of old electric tape possibly hiding rust spots

Overall, if you are looking for a new bike, consider taking a look at older ones as well.

Drilling holes without making a mess

2022-07-24T00:00:00Z

When you drill a hole in a wall, the excess needs to go somewhere. Traditionally, you use a vacuum to suck it up while drilling, but that takes an extra hand or some helper. There are also ring-shaped adapters which go around the drill, and I've used them with varying degrees of success in the past. I've seen a "hack" to put a folded post-it note below the place where you drill, but that never really worked for me either. It is just too flimsy, I often dunked the contents when trying to take it off and to the bin. Maybe that is a Europe problem, where walls are made from bricks instead of wood and there is more material coming out. Anyway, the theory behind it is certainly sound, even if execution always seemed lacking for me.

However, today I installed a shelf above my bed, which had white linen on it, and I really did not want to get red brick dust on it, or spend the time to cover it completely. In addition, I was balancing on a super fluffy bed with an impact driver and did not have any hands to spare. I did however have an old cardboard box and painters tape sitting around.

Just tape a container below your hole

Drill through the tape to reduce tearout

Overall, this worked great. Everything drops directly into the box, no cleanup other than taking the box to the trash was necessary, and it was even possible to reuse the tape to glue the box to several positions along the wall where I wanted to drill. This solution is pretty obvious, but worked way better than any other I'd tried so far, so I thought I'd share.

Building a Voron 2.4

2022-04-16T00:00:00Z

In the last months, I've gotten a replacement 3D printer. Sticking with more tinker-heavy machines, I replaced my Kossel with a Voron 2.4. This post summarizes my experiences building it.

Choosing the Voron

I started my FDM journey deciding to build a 3D printer because I was in the middle of my first university exams and wanted something practical to go along with all the theory. I had to tinker a lot over the years to keep it running at the performance I wanted from it, and I wanted something more compact, faster and reliable. But since I learned a lot from it, I wanted a machine which I could build and improve myself.

Over the years I watched a lot of Thomas Sanladerer's videos, and at some point he build a Voron 2.4. I also looked at some similar alternatives, like the Rat Rig V-Core 3, but somehow I just liked the Voron mechanics and aesthetics more. I also liked the concept of sourcing the parts from whereever you got them yourself.

Getting the parts

Somewhat ironically, I didn't really have the time to source everything myself, so I grabbed a Formbot kit off Aliexpress which included basically all parts. I waited apprehensively for two weeks until the delivery guy left it in front of my house without ringing the bell. Given that this was my largest order on aliexpress ever, that left me a bit surprised, especially since they had carried a 5$ amazon packet to a post office 4km down the road the other day, but hey, at least nobody stole it.

Formbot and Print-It-Forward parts

Then I got onto the Voron Discord server to join the Print-It-Forward Queue, where other verified Voron owners print the basic parts you need to get started. In hindsight I should have done this as soon as I ordered the parts, as I started out around spot 120 in the queue and had to wait 4 weeks until I reached the top. I chose orange as an accent color and a black as a main color. Once it was my turn, a swell guy called Stephan handled my order super fast, and a couple days later I had a packet full of ABS parts and got to unpacking the gigantic package from Aliexpress.

The basic build

The Voron website has a fantastic build manual, and apart from 2 or 3 spots it was always clear what to do. Several times the guide linked to youtube videos for more tricky sections which broke down perfectly what to do. For some reason the kit also included 8 similar linear rails, when only 7 were needed, and the one for Y-movement should have had a bigger slider head to attach the printed parts correctly, so I ordered a suitable one. The main issue I faced was that I accidentally got the parts for a Dragon hotend instead of a V6 hotend, but Stephan quickly sent me the correct parts once I reached out. My build plate was missing holes for the fuse and ground, but that was quick to remedy. My Formbot kit also included a wrong inductive sensor, which protuded a bit more than it should, but since it was still 2-3 mm above my nozzle, that wasn't problematic in most prints. I have since replaced it, but it worked for 50+ prints. My power inlet was not the main recommended one, so the skirt part I got was not suitable. I also missed a bracket for a power supply. I attached both with a zip tie and kept going. At a few points I ran out of T-Nut inserts for M5 screws and temporarily affixed parts with M3 screws with washers until my resupply arrived, but other than that everything went nicely. I reached the state of print-readyness. At that point, the parts from the Print-It-Forward request run out, and you have to print the rest - namely skirt parts, holders for the enclosure, etc - yourself.

Initial startup

The Voron website has great guides for initial setup and tuning. Somehow I ended up installing Octoprint first, despite being unnecessary, but then switched over to Mainsail and Klipper. I tested all the electronics and inverted and finetuned a couple of homing sensors, but basically everything worked out of the box. The first test print was naturally the Voron test cube. Halfway through, the old black PLA filament roll which I used ran out and I switched to another without problems, something which would have never worked that easily on my old Kossel, especially while using the interface for the first time.

The enclosure and skirt

With the baby issues handled, I started pumping out parts to hold the LCD, the power inlet, and the fans to cool the electronics. Then I quickly threw together a wire brush holder, because I did not want to manually clean the nozzle at each print start. That drastically improved usability.

It also showed off quickly how good the klipper interface is. It provides custom G-Code macros, and within 10mins I had whipped up a nozzle cleaning macro which would brush off my nozzle across the brush thrice before homing again and starting the print. No need to port that to Cura, it is just part of the machines own startup - where it belongs in my opinion, as the brush position is highly machine specific.

With that cleared, I alternated other projects and printer parts, first finishing off the enclosure, then the skirt. Once the skirt was finished and I had all the parts ready to close off the electronics compartment, I rerouted all the cables once again. While I had tried to do it properly the first time round, I had added some electronics like fans and a camera, and I now knew it was going to stay that way for a while.

Finished Voron

Experience so far

The Voron is fast. I usually print around 120mm/s, but have seen no problems upping that speed to 250%.

My extruder motor is running a bit hot, so it might get some cooling fins soon.

The flexible bed is way more practical for print removal than my previous Kossel print bed, but that is nothing voron-specific.

The firmware and web interface are super comfortable to use.

The guides online are usually clear and comprehensive.

The entire machine seems well thought out and there are even some template parts printed especially for alignment of other parts during the build, which makes everything a breeze.

I usually do nothing more than upload the file to start a print, and every few prints check the nozzle and wipe down the bed with soup water and isopropanol.

My print history shows 2/3 of my 150 prints so far were successful, and those include all the tuning prints in the beginning which I usually aborted before the end.

Overall, I would guess my current print success rate is around 80-90%, and the machine feels like I don't need to spend any effort on preparation besides slicing.

I still wouldn't recommend it if you don't like tinkering, and to be honest, you could get 3-5 Enders for the 1200€ I paid altogether, so while it is fast, it might not be the best bargain if you are going for sheer volume.

It is however also super easy to mod, repair and upgrade and just generally a huge joy to use, so if you want that, I can absolutely recommend the Voron 2.4.

Review: Detective - A modern crime boardgame

2021-12-13T00:00:00Z

Having played a great boardgame recently, here are my thoughts on it.

One of my prime hobbies is playing board games. Recently I played Detective, a crime board game, which was really great, so I thought I'd write about it so others might get to have the same experience.

What is Detective?

Detective takes up the a storyline similar to many crime TV series: A crime happens. The players take different roles on the team of investigators. Different clues and leads appear and can be followed. Each clue takes time or resources, which come in the form of the special skills of the different players' roles. Usually each case imposes a time limit. Visiting different locations also takes additional time, so clever planning brings you an advantage. Clue by clue, you can piece together the plot behind the crime.

Most clues come in the form of printed cards, which contain informations. Sometimes you can dig deeper, using extra effort, in which case you usually get to flip the card over and read the back side. But in addition to this traditional setup, an entire online database exists: It contains personal files, DNA and fingerprint comparisons to match criminals to clues left on the crime scene, records of interviews with certain people. You will gradually uncover them by following the clues.

At other places you will get clues which you can search on the open web: places in the real world, historical events, references to certain objects and organizations which are woven into the plot.

Which brings me to one of the real selling points of the game: The plot of all cases is built around real historical events, adding the sense that something similar could actually have happened. It references real political changes to give characters motivation. And some real locations are used, which can and should be googled.

The game contains 5 separate cases. While each can be played on its own, they are linked, and I would suggest playing it as you would play a DnD campaign: with 4-5 people which are not afraid of reading things for playing, and which will be able to make time for this 5-6 times in a row, so you don't have to change people while playing. Each case can affect subsequent cases, depending on which leads you follow. At the end of each case there is a final report in the online database which will tell you which of your assumptions were correct.

Each person gets their own role with special abilities in game, but we usually decided as a group what ability will be used, so it didn't really feel that important. More important was the player's role outside: Usually one or two persons read the clue cards, one person with a laptop scoured the online database for facts and stuff, one person with a smartphone or laptop did the general web searches, and one person tracked major stuff on a whiteboard. Yes, we used an actual whiteboard. The game actually encourages this and gives you mugshots of certain people to pin to it and connect with lines to try and grasp all the connections. It really gives you that feeling of being that conspiracy guy in that meme with all the documents pinned to the wall connected by red strings. In some later cases we actually moved to a digital whiteboard (miro in our case) as the story grew too big for our whiteboard. It's great for shared access and collaboration, and was easier to transport when we played at a different friends house.

Verdict

We had a lot of fun playing this. The 5 cases present a captivating story and the different mechanisms employed in different cases to change the rules up a bit keep each case unique. We played the German version of this game, which only had 2-3 minor mistranslations. The only real complaint I have is that the box said 2-3 hours of play time per case. We usually played 5-6 hours, but also always tried to follow as many clues as possible, so maybe that's on us. One case actually took us two evenings, so overall this thing took us around 30 hours to play.

Given that it costs around 25€, I'd say that it is a great deal. Go try it out for yourselves!

WARNING: Spoilers ahead! Below is a screenshot of our whiteboard for the entire case. Though somewhat pixelated, it gives a rough impression of the amount of clues we collected for all the cases

Spoiler

SPOILERS: Our finished Miro whiteboard (the left side shows a pic of our original whiteboard)