[HN Gopher] A complete guide to building a hand-wired keyboard (...
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A complete guide to building a hand-wired keyboard (2020)
Author : bfm
Score : 82 points
Date : 2023-08-22 09:59 UTC (1 days ago)
(HTM) web link (www.crackedthecode.co)
(TXT) w3m dump (www.crackedthecode.co)
| sleepybrett wrote:
| If you want to understand how keyboards function go ahead and do
| this, but unless you want a really wild layout this is just
| makework. There are cheap, reliable and flexible pcbs for just
| about every layout you could want available on the open market
| from sites like kbdfans and aliexpress not to mention dozens of
| local mom and pop sites that service the mechanical keyboard
| industry. It's a pretty big hobby these days.
| genpfault wrote:
| Any good, mostly-automatic tooling to go from a Keyboard Layout
| Editor (KLE)[1] JSON to a laid-out (not necessarily routed) PCB
| design in something like KiCad?
|
| [1]: http://www.keyboard-layout-editor.com/
| onetimeuse92304 wrote:
| As an amateur EE, here my thoughts.
|
| If you can do CAD you can probably also design a PCB with a
| socket for some kind of general purpose MCU or even one of ready-
| made keyboard controllers.
|
| Through-hole soldering is IMO actually simpler than making these
| "spiders" (that's how in my country we call circuits with self-
| supported wire to wire joints, usually with at least some
| components hanging in air by their leads).
|
| "Spiders" are prone to breaking with any repeatable mechanical
| strain. In case of this keyboard, what I am seeing is the plastic
| board will flex and will put repeatable strain on the wires,
| possibly leading to malfunction at some point. PCB would be much
| more reliable (if done correctly) as it would take most or all of
| the load from the joints.
|
| A thicker PCB board would actually be more stiff than the plastic
| board you have here. Not only materials of PCBs tend to be very
| tough, the PCB, being below the level of the switches, would need
| much less cutouts that are weakening your plastic mounting board.
|
| Stiffness of the board the switches are mounted to is important
| not just for the reliability, but also for the overall feel of
| the mechanical keyboard. This "feel" is mainly affected by the
| switches, the stiffness of the board, and the acoustics of the
| enclosure.
|
| And lastly, as an amateur EE I find "spiders" appealing (if done
| nicely, artfully). But if you want to showoff for the larger
| audience that just "don't get it", a custom PCB would immediately
| score more points.
| spinningarrow wrote:
| I think the biggest advantage of point to point wiring for a
| lot of people is that you can simply go ahead and do it at
| home. For PCBs, you need to know how to use one of the design
| tools but more importantly you need to find a place to print
| them.
| baz00 wrote:
| It's really easy to do. Particularly the getting them made
| bit. I just did a quote for a 2 layer board that's TKL
| keyboard sized and to get 5 made it's about PS20 delivered to
| my door from JLCPCB.
| rmaus wrote:
| There are certain kinds of fully custom keyboards, such as the
| one I use (Dactyl Manuform) where the keys do not sit on a
| single flat plane. Such a build would require a flexible PCB.
| This is doable for the advanced-amateur EE but the geometry is
| fiddly, at best, and doesn't allow for easy experimentation on
| key placement (spacing, offset, radius, etc, the bigger problem
| for me).
|
| I've found the happy medium with single-switch PCBs ("Amoeba"
| is a popular one), which are fast and easy to wire up. Most
| notably you don't have to do the painstaking row wire stripping
| -- just use a plain wire from one PCB to the next in the key
| matrix (or an insulated wire if you have to traverse other
| components, which still only requires two stripped ends).
|
| I have a few pictures floating around from my build(s) if that
| interests anyone.
| onetimeuse92304 wrote:
| Couple years ago I started building my own keyboard from
| scratch. Custom PCB, custom circuit design, custom MCU,
| custom programming, custom CNC-ed enclosure, some custom
| keys... In hindsight I should have relaxed a bit on building
| everything custom and then maybe I would have finished it.
|
| The main idea was to get a keyboard with built in steno and
| ability to get programmed any way I want. It would also have
| a small built in OLED display to aid some of the
| functionality.
|
| Another idea was to have built in mouse (trackpoint + keys
| that can be used as mouse keys).
| 533474 wrote:
| I'm interested in your build ;)
| rmaus wrote:
| https://imgur.com/a/wyqPSeo (unsure why this is marked 18+,
| sorry; it's SFW).
|
| You can see my first build (blue) in several of these
| pictures following similar advice to OP's guide (looping
| diodes, etc), with one modification where I used copper
| tape for the columns instead of wires.
|
| Then the first picture you can see how much cleaner the
| single-switch PCB ends up, and I can assure it was far
| easier to solder / strip / assemble.
| munificent wrote:
| In English, I think it's "point-to-point":
|
| https://en.wikipedia.org/wiki/Point-to-point_construction
| baz00 wrote:
| Yeah this on all counts.
|
| Ultimately it's probably better to have a triple-layer for the
| keyboard from what I can see. The faceplate that the switches
| are mounted on, the PCB and then the back plate. Could probably
| sandwich it all together easily.
|
| There's nothing wrong with dead bug though but on this scale
| and reliability requirements and mechanical stress, it's the
| wrong solution for the problem.
| fellerts wrote:
| This method is usually referred to as "Dead Bug" style wiring
| in English, because the end result usually resembles a dead bug
| with its legs curled inwards.
| Luc wrote:
| IMHO 'dead bug' used to refer to transistors, ICs etc
| soldered upside down, but it's true that lately it's used
| more generally. I would call this 'free form' soldering,
| since there's no dead IC in sight.
| onetimeuse92304 wrote:
| No, it is not. Although I can't fault you for thinking this
| as there are so many people using this term incorrectly.
|
| "Dead bug" is referring to mounting chips on their back with
| wires connected to leads going in all directions. Hence
| "dead" -- live bugs don't usually spend time laying on their
| backs. When you see it you immediately know why it is called
| "dead bug"...
|
| Here, this is how it looks like:
| http://dangerousprototypes.com/blog/2012/11/15/fine-pitch-
| bg...
|
| This technique is usually used to connect to leads of
| packages that usually have their leads hidden on the bottom
| of the package (for example BGA). These packages usually
| require a PCB made for them or some kind of adapter. They
| also require a bit more complex soldering process that might
| be just out of reach of an enthusiast (like good hot air
| station or reflow oven, etc.) If you find yourself with a
| component you want to quickly test and don't have an
| adapter... you improvise and this may result in a dead bug. I
| did it a lot of times myself.
|
| This technique is also sometimes used in production where
| they have an existing through hole board (or other board that
| is incompatible with the process required to mount the
| component). Sometimes it is easier to just "dead bug" the
| component than redesign entire board for the new process.
| ajsnigrutin wrote:
| As an non-amateur EE, i fully agree with this. If you can draw
| a basic circuit for 9 keys on paper, you can draw a full-
| keyboard one in many of the easy cheap PCB platforms, most of
| which offer a web interface (no installation of any weird
| software), rendered 3d views and a very cheap production price.
|
| If you really want to do it without a chinese PCB manufacturer,
| you can do it on a perf board (
| https://en.wikipedia.org/wiki/Perfboard ). If you have more
| GPIOs than keys (eg when building a very cheap steam deck with
| 9/12 keys), you don't even need any kind of "matrix"
| multiplexing, and you can just connect the keys to individual
| gpio pins. If you take a better microcontroller than a teensy,
| you also get bluetooth (and wifi) capabilities, like with eg.
| esp32 (~$5 on aliexpress).
|
| But either way, doing fun electronics, be it on a pcb or when
| soldering "in the air" is a lot better waste of money and time
| than many other things most people do.
| qwerty456127 wrote:
| Sounds very interesting. I have looked through premium and
| "custom" keyboards market recently and found out their customness
| mostly is about look&feel, key placement and omitting
| "unnecessary" keys while I want a positively custom set of keys:
| as many keys as possible - full keypad, multimedia keys separate
| from f1-12 keys, Windows context menu key, also programmable
| macro keys if possible, no spatial "optimizations" (when
| manufacturers try to fit all the keys into as little area as
| possible) etc. I concluded I will probably have to really build
| my own. My ideal keyboard would even have a ThinkPad-style
| trackpoint so I could operate the mouse pointer comfortably
| without removing my hands from the home row :-)
| rgoulter wrote:
| > omitting "unnecessary" keys .... without removing my hands
| from the home row
|
| The "keep hands on home row" is the motivation behind omitting
| the "unnecessary" keys, at least for the keyboards which use a
| small spacebar and give the thumbs more keys to use.
|
| With those small 36-key keyboards, your hands pretty much have
| nowhere to go except to remain on home row.
|
| > as many keys as possible
|
| I once saw someone made a keyboard with 450 keys.
| https://relivesight.com/projects/433/
| qwerty456127 wrote:
| I don't really care that much about the home row (although
| it's nice to have something right in it so I mentioned). I
| care about being able to do everything by pressing less keys.
| Meanwhile a language I often type in (and I type in quite a
| number of them regularly) has the digits row remapped for
| extra letters so I can't enter a digit with a single key
| press without a keypad (I prefer moving a hand to there over
| using modifier keys). I also make heavy use of F1-12 keys and
| I have long thin fingers so I woudn't even mind an additional
| row of keys. Using the mouse every time I want to adjust the
| sound volume or do something like this is annoying as well.
| Needless to say I actively use Home, End, PgUp, PgDn and
| Insert (many compact keyboards lack some of these). At last
| but not at least, for sake of the muscle memory, I would
| prefer all the keys to be located at the same places on all
| the keyboards rather than moved to whatever a place the
| vendor has been able to fit them in.
| Mizoguchi wrote:
| These small keyboards are usually ortholinear which also
| helps reducing hand movement.
|
| I switched to a OLKB Preonic over a year ago and haven't
| looked back.
|
| After you get used to the smaller factor and non staggered
| keys format you realize how ridiculously and unnecessarily
| huge and clunky traditional keyboards are, even laptop
| keyboards.
|
| It's like traveling with a 65 liters bag for years before you
| learn you can just carry a 40L and travel with less crap and
| much lighter.
|
| It took me a couple of months to come up with the layout that
| worked for me (and even today I still optimizing it), but
| once I figured it out the typing experience became just such
| much better.
|
| The QMK configuration tool makes the process of configuring
| the layout painless and super quick, so you just need the
| patience to try and iterate.
| sleepybrett wrote:
| less keys = more cognitive overhead. Having to remember
| what layer i put fucking pipe on is not better than just
| hitting the damn key.
|
| In ~2000 I started suffering from tendonitis and my coding
| job became very painful, I tried kind of the 'easy onramp'
| ergo options at the time, namely the ms 'natural'. It did
| not help. Eventually someone pointed me at the kinesis
| advantage (then essential) and I bought one. After some
| struggle coming to terms with thumb keys and wells and
| ortholinerness I switched to it for all tasks except for
| gaming and my symptoms basically disapeared.
|
| About 10 years back I was in a job that was potentially
| going to cause me to travel a lot, at that point I had
| already modded my kinesis advange keyboards with custom
| controllers and wanted to try and build something that
| travelled better, was smaller, while still not fucking up
| my wrists.
|
| I built a _lot_ of keyboards trying to shrink my luggage. I
| went ortho and built a split preonic, uncomfortable, then I
| went down the road that leads to corne /iris/etc (thumb
| keys, vertically aligned but not horizontally aligned).
| More comfortable but the thing i always ran into when
| removing keys. Overhead, you have to remember what layer
| and key you put xyz rarely used symbol on (and when you are
| a software engineer that's a lot of the symbols).. at the
| end of the road I built a very low profile board based on
| the dactyl with the same number of keys as the kinesis
| advantage minus the f-key chicklets. Reducing the number of
| layers i have to remember to 1 that only contains the grave
| and the fkeys.
|
| Then covid hit and I didn't have to travel anywhere. I take
| my dactyl when I go see my parents, and unloaded most of my
| other boards for cheap. (i kept a 65 that I play games
| with)
| unnouinceput wrote:
| Same here. All these modern keyboards are missing a lot of what
| old one had. The most I miss most is the Alt GR one, the bigger
| ENTER key and I want a lot of space. Call me fat fingers if you
| want.
|
| So I started to actually create my own. And I want it to be
| programmable. And movable, as in you can move the key around,
| enlarge or shrink them. And when I say I want them programmable
| I meant to pull a little gizmo out of it, hook it up to a
| separate power source and load preset or connect to computer
| and use an app to make the keys look different.
|
| So far my idea is to have each key include a magnet, an ESP32
| chip and a small LED screen on top of it. The controller to all
| those 110+ ESP32 chips will be a RPi CM4 module, which will
| also be the USB connection for the PC. That's one iteration
| because this way I can actually have a click-clack mechanical
| one. The other iteration is to just have a big ass touch screen
| and the RPI underneath to just play that as an app that
| simulates the keyboard. Prettier, way more customizable as key
| positions/size go but no click-clack sound/feeling.
|
| I'm $2000 in my research hole for this with nothing to show up
| for but is fun. Probably next year I'll finish it :)
| jan_Sate wrote:
| I wouldn't recommend using ESP32 for that. It's overpowered
| for this application. You don't even need its wireless
| connectivity. I guess using something like RP2040 or ATTiny
| would be a better option.
| nick__m wrote:
| why an esp32 instead something simpler like an stm8 (or an
| stm32f103c8t6 if you need arduino compatibility) if you
| really want an mcu per key ?
| unnouinceput wrote:
| because I'm experienced in ESP32 and not in STM8. But now
| that you mention it, a little seed started to grow. Thank
| you kind stranger, lemme get back to you when this will
| probably 2 years from now on and another $2000 in
| research/playing around.
| qwerty456127 wrote:
| I agree but I don't need the keys look anything. The best
| thing happened to my keyboard life so far was having to use a
| keyboard without the letters of a language I used daily drawn
| on it. I would rather buy "das keyboard" with purely black
| keys but it doesn't have enough keys for me to invest in.
|
| However, I would love to have your software-defined visually
| configurable keyboard as a second one on my table and every
| app using it as a sorg of a "toolbar" / command palette. This
| was what Apple tried sort of (it would have been nice idea if
| they didn't sacrifice a real keys row for it). To me it
| sounds like an additional display with touch support can do
| the job.
| unnouinceput wrote:
| The LED display on top of the key, driven by the ESP32
| beneath, will allow you to have anything as the letter
| there, including Arabic, Japanese or just emoji keyboard
| layout.
| drekipus wrote:
| Really you probably just want a normal keyboard with some good
| firmware.
|
| I started out with a moonlander, which had a lot of keys (36
| each hand) but to be honest, I'm trying to minimise as much as
| possible, and remove keys from it. That way I'm fully
| constrained to the home row.
|
| Also, layers are amazing and sounds like something you might
| want to look into. Hold 'a' and use hjkl for media keys, etc.
| It's all very flexible
| qwerty456127 wrote:
| I never knew there are keyboards with configurable firmwares,
| also never heard about layers. Your comment sounds very
| helpful, thank you. By the way I already considered buying a
| Moonlander because of its 2-part design - I have an idea of
| possibly using a computer while lying on the floor sort of
| like in the Shavasana posture with my hands by my sides
| rather than in front of me.
| digging wrote:
| > also never heard about layers
|
| I was just discussing this yesterday with a friend. It's
| funny how rare and technical it is to understand layers
| when everyone uses layers every day - shift + 3 does not
| render 3, but #. But we don't talk about it that way.
| wakeupcall wrote:
| My impression for the popularity of the 75% form factor is due
| to laptops and people being accustomed to never have used the
| "missing" keys in the first place. A tell-tale is that default
| layout even for thinkpads is to set the Fn row to media keys by
| default... An increasingly smaller number of people use them,
| despite being a row of freely remappable keys right _there_.
|
| What I've seen happen though is that especially on linux you
| need two-modifier combos (ctrl-shift/ctrl-alt) to perform what
| you could have done with a single Fn keystroke. Or burn a few
| extra keys and increase complexity with layers. I went this
| route a decade ago, and I'm not a fan personally. Removing the
| Fn row saves 2cm of vertical space from your desk. I see it as
| completely pointless, even if you never use the Fn keys.
|
| And I don't buy the "reduced finger travel" argument either.
| Holding the modifiers in weird positions to access an extra
| layer is usually worse than a more spacious keyboard where your
| hands can be kept further apart and require less chording.
|
| But yeah... I commented on another thread on keyboards, and the
| current keyboard craze is mostly about customization and looks,
| and very little about the actual typing experience IMHO (there
| are exceptions of course..).
| ako wrote:
| Problem with the Fn keys is discoverability: i never remember
| which functionality is available on which key, and you have
| to remember different mappings for different apps. Actually
| thought Apple's solution for this, the touchbar, was pretty
| nice, sad that it failed...
| qwerty456127 wrote:
| Back in the days when first computer keyboards were invented
| 7-bit ASCII was enough for everybody, now as everyone
| everywhere uses Internet daily for all sorts of tasks we have
| Unicode.
|
| People don't need a keypad because they have the digits row.
| But there are languages (in Europe) which reuse the digits
| row for extra letters (which don't even fit there) so you
| have to press shift to enter a digit (yes, you can't enter
| such a letter in capital without using CapsLock), unless you
| have a kaypad.
|
| People don't need F-keys (so these can be reused for
| multimedia controls) because they are not techies. Insert for
| the same reason.
|
| People don't use Delete/Home/End/PgUp/PgDn because they are
| completely uneducated about the basics of using a computer
| and use mouse/touchpad, arrows and backspace instead. Believe
| it or not, I've met people who don't even know Ctrl+C/V (let
| alone Ctrl+X or Ctrl+Z) and would always use the right-click
| menu (which even requires an additional keyboard key to be
| held pressed on a Mac) to copy/paste anything.
|
| This said, compact keyboards target anglophone non-techie
| users (or hardcore VIM fans who have ways to do everything
| without leaving the home row).
| Symbiote wrote:
| > But there are languages (in Europe)
|
| The languages appears to be Czech/Slovak. It would be more
| useful to mention this, than to repeat the basic point in
| four or five comments.
| eviks wrote:
| > Holding the modifiers in weird positions to access an extra
| layer is usually worse
|
| What's weird about home row or thumb mods?
| hnlmorg wrote:
| I completely agree. I never understood this craze of removing
| keys.
|
| The number pad is another example of this. Typing numbers is
| massively more comfortable (and quicker too) on the number
| pad than it is with the row of numbers just below the F-keys.
|
| The amount of desk space people save is so negligible,
| particularly when people who buy these keyboards typically
| work in "paperless" offices, that I never understood the
| appeal.
|
| I guess it boils down to people wanting their keyboards to
| look pretty rather than being actually useful.
| eviks wrote:
| Why would you move your hand to the numpad if you can use
| your orthostaggered "numpad" with a layer right where your
| hand already is on the alpha keys?
| hnlmorg wrote:
| Because moving your hand is a one time effort vs moving
| it up and down the keyboard to enter those pesky 6 digit
| TOTP codes where the digits could be at opposite ends of
| the keyboard.
|
| Plus I've been using keyboards longer than a lot of
| (probably most) developers on here have been alive and I
| haven't ever found using the number pad to be even
| remotely an effort.
| eviks wrote:
| It's a one time effort you can easily avoid with a much
| smaller one time effort (tapping/holding a very
| convenient numpad layer modifier). And it's especially a
| wasted effort for very short numbers like TOTPs
|
| And all the digits are right there, not at some opposite
| ends, e.g., UIO789 JKL456 M,.123 on a qwerty
| qwerty456127 wrote:
| As I already mentioned 4-5 times, one of the languages I
| use regularly reuses the number row for extra letters
| (and it isn't even enough for all of them). I have to
| hold Shift pressed to enter a number this way (using a
| keypad feels much better) or use CapsLock to enter a
| capital of such a letter.
| eviks wrote:
| My comment is about NOT using the number row, so your
| repetition is not a relevant response
| glormph wrote:
| I agree that looks and deskspace is not something to
| optimize for and number entering is great on the number
| pad, but the ergonomics expert at my job informed us that
| shorter hand travel to the mouse is better against
| straining or something, so not using numpads would help. Or
| move the mouse/trackpad to the left.
| joncrocks wrote:
| I think it's a concession that use of particular parts of
| the keyboard is person and context specific.
|
| e.g. At home, I only very occasionally enter numbers. I
| very frequently use my mouse, and have large monitors. So I
| sacrifice slightly less convenient number entry for
| slightly more room for my mouse(pad) all the time.
|
| At work, I have a full-size keyboard and I spend a higher
| proportion of my time typing and entering numbers.
| qwerty456127 wrote:
| Isn't it better to have identical keyboards everywhere
| for sake of muscle memory?
| nlunbeck wrote:
| This is my #1 priority now that I'm in the market for a
| new keyboard. I lose so much typing efficiency when
| switching between laptops, so functionality or comfort is
| no longer a leading factor for me.
| rgoulter wrote:
| > I never understood this craze of removing keys.
|
| There are (roughly) two families of "smaller keyboards".
|
| Those with a big spacebar, and those with multiple
| thumbkeys.
|
| Big-spacebar-small-keyboards are like laptop keyboards.
|
| Whereas, for other kinds of small keyboards (such as the
| moonlander or planck) which provide thumbkeys, I'd say the
| emphasis is more about "bringing the full functionality of
| the keyboard to within easy reach of the hands" rather than
| "remove keys for whatever reason".
|
| On traditional keyboards, the thumbs only get to use 1 key.
| A big spacebar is such an odd and inefficient use of
| keyboard real estate.
|
| Whereas, with 2-3 keys each, the thumbs can be put to good
| use. e.g. It's much more comfortable to press backspace
| with the thumb, than to move your hand (or reach with the
| pinky finger).
| qwerty456127 wrote:
| > Typing numbers is massively more comfortable (and quicker
| too) on the number pad than it is with the row of numbers
|
| Let alone than with the row of numbers holding a Shift
| pressed (some languages require this because they remap the
| row for extra letters).
| SoftTalker wrote:
| For many people who rarely need to type numbers, the number
| pad is wasted space. If you're an accountant you probably
| want one. Maybe even a separate, dedicated one.
|
| I rarely type numbers and find that the "top row" number
| keys are adequate for when I need to.
| delta_p_delta_x wrote:
| I do think a full-size 108-key board wastes a lot of space,
| but a 96%, similar to what's seen on full-size workstation
| notebooks (Dell Precision 7000 series, HP Zbook Fury,
| Lenovo ThinkPad P series) is much more efficient, while
| still providing Home, End, PgUp/Dn, Delete, Insert, arrow
| keys, and a full num-pad.
| where-group-by wrote:
| I got a keyboard without the numpad due to the looks, but
| after using it a few years the full sized ones feel too
| bulky. I have to either move the mouse much further to the
| right or have my arms bent to the left when typing. Neither
| of which feels comfortable. I'm sure I could switch back if
| I needed to, but that extra space is welcome.
|
| I agree entering numbers is better on a keypad though.
| thejosh wrote:
| Keyboards are getting smaller, but I love full size ones for
| programming.
|
| I ended up getting the keychron v6, it's wired but fine. Their
| wireless keyboards are apparently a bit buggy, not sure if the
| new ones still are.
|
| QMK is an absolute treasure. You can use your web UI to setup
| custom keymaps and stuff using the chrome USB feature. But I
| may have went off the rails, as it's pretty simple to
| completely customise your keyboard with layers etc if you know
| a bit of C.
|
| Warning; this is a gateway into a land of a obsession. :-)
| hellweaver666 wrote:
| Building your own keyboards is super satisfying. I started off
| hand-wiring a couple of macropads and then built a 60% handwire
| and a split ergo. Finally with all the knowledge I learnt I
| designed a PCB for a macropad and then just scaled up to my own
| keyboard which is a 50% ortholinear keyboard which has three
| extra "macro" switches on the side. I found a switch footprint
| that allows it to take "normal" or "low profile" style switches
| so I have a version for home and a super slim version for taking
| to the office.
|
| I think the only thing I would do differently now is to dump QMK
| and use KMK instead as it's Circuit Python based which means that
| the firmware can be created and edited directly with your
| favourite IDE (QMK requires installing all sorts of extra
| software and compiling etc). If the Microcontroller ever dies on
| this board I will definitely swap it out for a CircuitPython
| compatible alternative!
| winrid wrote:
| What I really want is a mechanical backlit keyboard without
| terrible PWM flicker. It's so hard on the eyes. Just regular DC
| dimming would be ideal.
| thorncorona wrote:
| Much easier to just up the PWM frequency
| beeforpork wrote:
| Soldering 1N4148 so close to the glass body, plus using a thick
| drop of solder, makes it really easy to overheat the diode. They
| are everywhere because they are cheap, not because they are
| robust... The diodes may become unconditionally conductive, so it
| may not be an obvious bug.
|
| I fried many of them, because my soldering skills were not that
| good, I did not read the data sheet and so my iron was too hot
| and I soldered them for too long. Plus by using short wires, all
| the heat transferred into that fragile glass body.
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(page generated 2023-08-23 23:01 UTC)