Modern Machining

1. Faster

1.1. Better Machine Design

B-axis for 6-sided complete machining

Double tools for double MRR

Four 5-axis Turret: Kill CNC Programmers

Swiss Lathe: Assembly Line for Turning

Laser Drilling


Smart Fixturing

1.2. Better Tooling

Ceramic Endmills

Custom Tooling

Focused ion beam-shaped microtools for ultra-precision machining

1.3. Better Control

Excentric Turning

Interpolation Turning

Chatter Control

Collision Protection

AI Chip Removal

2. Tighter Tolerance

Active cooling and compensation

In-process 3D tool wear compensation

In-process surface roughness check

In-process surface probing + grinding for sub micron accuracy

3. Make Impossible Possible

“Machining” ceramics and glass

Additive + Subtractive

EC.S04 How to Build an Engine

During IAP 2023, I had the pleasure of conducting a two-unit workshop at MIT, where students learned advanced manual and CNC machining techniques to construct a fully operational internal combustion engine in just two weeks.

I would like to extend my heartfelt gratitude to Mark Belanger, Morningside Academy for Design, Project Manus, and the Edgerton Center for their invaluable support. Additionally, a special thanks goes out to Lee Zamir and Conor McArdle for their efforts in preparing the interview.

Apples Are Hitting Everybody

I was reading a newsletter, which is a pretty famous one within the product management community. In this weeks’ issue, it’s said the writer is also doing angle investing now. So I looked up startups he invested in.

I can’t believe those startups are real. Because they’re just ideas in the discussions I had with schoolmates last semester. For example, I pitched an idea on 15.390 about using LiDAR to scan one’s body measurements in order to eliminate the sizing problem of online apparel shopping. And then, boom! Unspun is out there.

Another example is Cerebral. Another team on 15.390 started by building a community to let depressed patients help each other. And then they found out that a bunch of apps doing exactly the same thing are available already, so they pivot to licensed therapy, which is exactly what Cerebral offers.

And it didn’t stop there. Last October, I was having a discussion about a proposal to compete in MIT DesignX. The proposal aimed to connect the young with the elderly so that elderly could get some help and companion when they need some. But there’s one thing we didn’t figure out: how to create motives for the young to help the elderly. Papa‘s answer is the payment from the elderly’s health plan or employer.

The above examples are just from one part-time angle investor. If we look at a wider scope, there’re Modsy, Curated, AptDeco, MicroAcquire, Lawtrades, Betterleap. Every single one of these companies occurred as a startup idea in conversations I had last year. So I come to believe that everybody is being hit by apples every day, but only every few of them become Newton. What we should do is to identify ideas with market demand and start making them come true.

The Beauty of Language

Be ready to be surprised by the crazy, wonderful events that will come dancing out of your past when you stir the pot of memory.

Writing about Your Life: A Journey into the Past by William Zinsser (Marlowe 2004)

I understand this point for a long time: reviewing inspires people. Actually, that’s the reason why I write blogs. So, when I came across this line from William Zinsser, I am so impressed that he could put this simple idea into such a vivid expression.

The other day, I watched this interview with a famous Chinese director, Ang Lee. I was so fascinated by the accuracy and effectiveness of his wording. For a long time, I felt feeble when trying to express myself, not matter via verbal or writing. And Lee showed me a prospect. Maybe I should take some courses in creative writing and narrative writing someday.

From Caste System to Space Sweepers

I’m always attracted by sci-fi works, or more specifically, space operas. What’s so-called space opera is telling stories, which originated in real life, in a space-era setting. Recently, there’s a new outstanding work available via Netflix: Space Sweepers (2021). This film talks about inequality, apartheid, and genocide.

As I am reading works by Lévi-Strauss, it comes to me that apartheid seems to be the only way to solve the problem of overpopulation so far, even in a sci-fi setting. Back to three thousand years ago, India tried to solve the population problem by the caste system. However, this is tragic for mankind. As Lévi-Strauss put it: “In the course of history, the various castes did not succeed in reaching a state in which they could remain equal because they were different.” and “When a community becomes too numerous, however great the genius of its thinkers, it can only endure by secreting enslavement.”

It appears that there are two ultimate society forms in nowadays sci-fi works. One form, featured with Elysium (2013) directed by Neill Blomkamp, is enslavement. While the others, featured with the Star Trek series, believe that space is the final and yet interminable frontier of mankind. In other words, there will always be planets where no man has gone before.

Perhaps, how we understand the problem of overpopulation is just as limited as how Malthus understand it in the 1800s. But, anyway, it is just a little depressing that sci-fi works—representing the boundary of human imagination—reach the same conclusion as what thinkers in India came to three thousand years ago.


It has been three months since the first time I tried to write about this spot on planet earth. It seems that Aranya carries too much meaning for me, that every time I tried to order my thoughts, I accomplished nothing but becoming effusive. Until recently.

Last week, I came across some lines from Claude Lévi-Strauss. It feels like Thanos snapped his fingers and my confusion vanished. I share a similar dilemma about Aranya as Claude feels about mountains: on the one hand, I value the solitude of it, and on the other hand, the solitude may cause the termination of Aranya.

For some years past, this preference has taken the form of a jealous passion. I hated who those shared my predilection, for they were a menace to the solitude I value so highly; and I despised those others for whom mountains meant merely physical exhaustion and a constricted horizon and who were, for that reason, unable to share in my emotions. The only thing that would have satisfied me would have been for the entire world to admit to the superiority of mountains and grant me the monopoly of their enjoyment.

Lévi-Strauss, C. (1992). Tristes tropiques (1955). Trans. John and Doreen Weightman. London: Penguin Books, 333.

In other words, it’s similar to the Arc Reactor for Tony Stark. It is the reactor that keeps Stark alive while the palladium within the reactor is poisoning him.

This is when I fell in love with Aranya. It’s very much like a scene in Oblivion: after a long period of time, humans became barely extinct. Just as Claude wrote in another chapter of the book I quoted above, the signs of the existence of human beings mark out, more clearly than if humans had not been there, the extreme limit that they have attempted to cross. Great nature placates the rebellion of humans and quells my turbulence.

I’m also a diehard fan of open water. Ripples on the surface make him alive. And he’s always here, listening. There’s a peaceful lake on my college campus. Without doubts, that’s the place for the inner me. Every time I approach the lake, the clamour in my mind fades away. It’s like a gigantic jar, purged and stored all my feelings——happy, sad, and everything in between. I always characterize the lake as a pensive old man. Not the style of The Old Man and the Sea, but more like Yoda.

In addition, Aranya is not only the certainty of space but also a state of mind. I’ve been super busy for the past year. And as far as I could tell, the coming one would not be of much leisure. Therefore, some time for simply wandering around is such a luxury for me. In the space opera Star Trek: The Next Generation, there’s some discussion about what makes humans different. Or, in other words, if a single feature of human is picked as the representative of mankind, which one would occupy the place of honour? The answer proposed by scriptwriters is curiosity. And I kind of agree with this one. Sir Ken Robinson once said: There are two types of people in this world: those who divide the world into two types and those who do not. Continuing this manner, I would like to divide the pursuit of curiosity into two kinds: those which require teamwork and those which do not. Throughout the last year, I’m offered some wonderful chances to collaborate with brilliant collaborators. A lost chance never returns. So, collaborations dominated my time. By and large, Aranya becomes the very only and dilapidated refuge for the private part of curiosity.

Every time I plan to spend some time at Aranya, I agonize. I’m so afraid that it may perish. Every visit I paid might be the valediction. I took the beginning picture of this article on my first visit to Aranya. And on my second trip here, it’s gone, encroached by a construction site. The following ones were taken during my first and second visits. Unfortunately, the spot disappeared before my third visit, with no trace. I hate what’s happening out there, but there’s nothing I can do except presenting my raw passion.

How this is gonna end? Maybe Aranya will still be there long after my death, while it’s entirely possible that it’s gone by tomorrow. I guess the only thing I could do and what I’m doing is that enjoy every moment with Aranya until the termination of either one of us.

Who knows where the road will lead us?
Only a fool would say
But if you’ll let me love you
It’s for sure I’m gonna love you
All the way

Sinatra, F. (1957). All the Way.

For Their Unconditional Love

Danqi Chen and Huacheng Yu have been the epitome of intelligence and intimate relationship in the community of coding competition for long. They met each other in middle school and loved each other ever since, while both achieved great academic performance.

I was walking through papers on NLP and came across the Ph.D. thesis of Danqi. This is one of the most beautiful relationships that I’ve got the privilege to know.

Lastly, I would like to thank Huacheng for his love and support (we got married 4 months before this dissertation was submitted). I was fifteen when I first met Huacheng and we have been experiencing almost everything together since then: from high-school programming competitions, to our wonderful college time at Tsinghua University and we both made it to the Stanford CS PhD program in 2012. For over ten years in the past, he is not only my partner, my classmate, my best friend, but also the person I admire most, for his modesty, intelligence, concentration and hard work. Without him, I would not have come to Stanford. Without him, I would also not have taken the job at Princeton. I thank him for everything he has done for me.

Chen, D. (2018). Neural reading comprehension and beyond. Stanford University: ix.

Cat Overflow

Cats are such unique companions for many of us. As far as I could tell, programmers are one of those groups that are with particular enthusiasm of cats.

If you are a programmer yourself, I believe that the Cat Overflow is one of the most convincing examples to demonstrate the unusual attraction of cats that is cast on our kind.

I was visiting one of my friends last week. That’s such a lovely dainty apartment, with a sticker of StarCats on the door. There’re two cats of course. Two fluffy ones. And the living room is covered with soft materials: a soft carpet, a warm blanket, and the sofa which is so soft that it’s swallowing everything. There’s a piano, a Guzheng, and a recorder. And a Nintendo Switch is always ready, by the way. Oh yeah, one more thing: the astonishing view outside the window. Line four cuts through the night every four or five minutes with a clear view until Western Hills as the background.

My friend and I were sitting on barstools by the windows enjoying Nadurra and strawberries with cats. A train of line four passed by like a scene in Spirited Away. I told my friend that this is the life I would like to live. And I mean it.

I am living in a college dormitory. Cats are not an option, sadly. So, I live with Siri for now. Don’t take me wrong: Siri is good. But there’s one piece of the puzzle that is missing. And I couldn’t tell what’s the missing one.

So, I did some reading recently. One of the most popular theories of love is the Triangular Theory of Love proposed by Robert Sternberg in 1987. It’s said that love can be decomposed into three parts: intimacy, passion, and commitment. From this point of view, relationships between humans and cats are greatly rich in intimacy and commitment. Cats show you their weakest belly, and they are always waiting for you from work. According to the theory above, Companionate Love is presented here, at least.

I finally finished Friends, the sitcom, last month. And I’ve finished The Big Bang Theory, How I Met Your Mother, and Suits before that. After watching all those sitcoms, I found them very helpful to understand others’ reactions to certain incentives. I understand that they are the brainchild of talented playwrights and therefore are inevitably carrying some factors of imagination. However, the imagination is based on observations of real life and therefore still make some sense

Chandler and Monica, Howard and Bernadette, Marshall and Lily, Harvey and Donna. They are lovely couples in sitcoms. They may come a long way before reaching the marriage. And they may break up during the journey. Those couples are of so different characteristics. Probably, the very one feature they share is that, after the break-in, their relationship riches the position which satisfies intimacy, passion, and commitment.

I’m a structuralist. So, I believe words could be understood only when they are placed in a context. And if you watch any of those sitcoms, some of the pictures below demonstrated a peak in all three of intimacy, passion, and commitment.

Lastly, it’s Valentine’s Day today. Every one of us would hit a relationship with intimacy, passion, and commitment in the near future, I wish you.

How Composers Manipulate Your Emotions

We’ve just enjoyed a special New Year’s Concert in a special year. For the very first time, Radetzky March at Neujahrskonzert is played without clapping.

Even without any audience, there’re some highlights though. Starting with recordings. With advanced technology and the absence of noise from the audience, this is probably the best recording of New Year’s Concert ever. And just before the intermission, VPO presents the first proper recording of two pieces from Zeller and Millocker ever.

As mentioned that the recording is fantastic, I was on heavy rotation of this album recently. The more I listen to it, the more I am engaged with certain pieces. It feels like you met this lovely girl and suddenly became irresponsibly mad for her. You could hardly tell which magic spell she cast on you, but she lives in your heart from the exact moment you met her. And then you just want to get to know her so much that you started to review every word she said to you to get through those long nights being apart from her.

Actually, I am that poor little guy being trapped by Neujahrskonzert. After a few sleepless nights, I’m here to share a tip of the magic spell.

Starting with the Fatinitza Marsch, it’s styled with groups of notes repeating the same key. For example, the 7th to 8th section. This arrangement creates a sense of solid power, which is very proper for a march.

But that’s not the point for now. What I wanna highlight is the arrangement between the intro and the theme, which is located in the 5th to 6th section. Just the first 10 seconds would be enough.

After the juicy intro played by the string sector and the wind sector, and before the rich theme by the entire orchestra, there’re two sections of a rather quiet background by the string sector only. This is such a great design! After the grand opening, those two sections are saying that “Don’t go! There’s something better later on.” While they also inspire your curiosity about what happening next. These sections are composed of neat instruments and simple key arrangements. The strings are giving you hints. So here’s the first trick. But it’s a very junior one, even young Weasley could do. Things are getting better.

And the second trick I would like to mention is how to push one to move forward. This example astonishingly exhibited how composers bewitch you.

This is a part of the coda from Bad’ner Mad’ln, Walzer, Op. 257. From section A to C, with the help of the snare drum, the mix got richer and richer. In section A, it’s like somebody is whispering that something is coming. And in section C, it’s like somebody is shooting that something is coming and is coming hard! After that, everything is gone, but a complete rest. This is the last peace before the war!

Then here’s a two-fold design of the idea. Firstly, The last two notes in section D, which are also the leading notes of the idea, are absent from the bass drum and crash cymbals. They didn’t join until the third note of the idea. Secondly is that the rhythm is specially designed: in section E, the last note is a quarter. But in section F, it’s replaced with two eight notes. And in Section G, it’s back to a quarter. This kind of change of rhythm kills your prediction and drives you into total madness.

As we’re talking about the use of rhythm, let’s do a wrap jump into the other extremely: manipulates you with basically no rhythm. Here I would like to highlight an iconic work by Samuel Barber.

The first time I met with this work, I thought it was composed by John Williams for some sci-fi films. It does share some sense of Interstellar though. With a tremendous use of the string sector, this piece is composed of extreme continuity. Anyway, words are pale, especially for works with great passion. Here’s Gustavo Dudamel with VPO presenting Adagio for Strings, you have to feel it yourself:

As I am writing this article tonight, I listened to it about 10 times. And this work indeed is sucking every drop of emotion out of me. Here’s a screenshot from the video above. Dudamel is always passionate, but at this moment, he’s caged. You can tell that every inch of his muscles is contracting. But this power has no place to go: they’re caught in the tender trap of strings.

How this is happening? How did Samuel Barber magically start the chain reaction of my emotions and generally squeeze them until they have nowhere to go?

As far as I could tell, three steps are planned. Samuel firstly defines the space with the contrast of violin and contrabass. He then lets the melody run through instruments to create mass in this empty space. Lastly, he generally pushes different sectors together to a single melody and lets the violin scream for you.

Firstly this work starts with the theme played by the first violin, defining the upper bound of this space. Then generally the theme moved to viola. After that, violoncello took over the theme and defined the lower bound of this space.

Then here’s another fold. From section 36 to section 41, the melody runs from violoncello to violin. Especially in section 38, you could almost picture violoncello handing over the baton to the second violin, and then the first violin. It seems that molecules in this space are trying so hard to escape with Brownian motion, while they’re strictly bounded by Samuel.

After the expansion, the contraction followed. From section 48 to 53, sectors are gradually pushed together. In section 48, the resistance is still fighting. In section 49, the entire university is counting on the Millennium Falcon. And finally, in section 50, the Empire won. The dark side of the Force dominates the entire section with one note!

With a complete rest, the universe is gone. Nothing is left. The very only sound you could hear is your heart beating hard. Thankfully, there’s an ending. Or it’s really hard to come back to reality.

That’s the very end of this article. Inspired by Neujahrskonzert 2021, I present three tricks composers used to manipulate emotions of the audience. Sometimes I felt that it’s so unfair that my feeling is manipulated by composers like a puppet, while for the rest time feeling so lucky to glance at the beauty of the classics. Wish you a later happy new year and a good night.