
Chinese Crankshafts (2012) - beerlord
https://flycorvair.net/2012/01/15/chinese-crankshafts/
======
mtw
There are videos where you see chinese doing metal work with made up tools and
just improvising it, like a group of rednecks. There are also high-tech
factories in China where robots and tight QA control are used. "Brady" here
tried to cut corners and bypassed the trust process that is absolutely
required in Chinese business. In American business, you spend time and money
in lawyers (post-business), in Chinese business, you spent time and money
selecting, vetting partners (pre-business) and building trust with them until
you know for sure they will view you as their "family". It doesn't mean you
can't get quality crankshafts from China, they produce aircraft from modern
commercial aircraft competing with Airbus to fifth generation fighters.

~~~
cauldron
Pretty sure all those Chinese high-tech factories' robots are either bought
from Germany, japan, or Taiwan.

Don't get me wrong, Chinese do manufacture these robots too，but from the
Chinese news reports I've read, the durability just isn't there, and they
relies on either Germany or Japan for key parts.

~~~
lb1lf
Just about any nation which has undergone large-scale industrialisation
started off copying someone else.

Swiss watches? Developed by British and French watchmakers escaping religious
persecution in their home countries.

Japanese cameras and other consumer electronics? Started off as cheap knock-
offs of Western products.

You learn a lot from importing technology and using it to copy stuff until you
reach a level of skill where you realise you can do this just as well as the
original makers.

That is the point where you start looking into other barriers to market share
- like poor QC, dodgy reputation etc. (Also, that is probably the point where
you start designing and building your own assembly lines, too.)

~~~
inferiorhuman
Camera-wise the Japanese and the Soviets got a bunch of tech from the Germans
after WW2. I'm sure the Chinese can (and probably will) eventually get to the
point where their manufacturing is highly regarded. To some extent that's
already happened as the lowest quality tier manufacturing is being shifted to
India and Vietnam.

But precision manufacturing is extremely difficult. There were a couple
comments musing about aviation stuff. Let's put it this way. Russia is very
good at certain types of manufacturing (e.g. rockets) to the point that NASA
uses Russian rockets to launch its satellites. Russia (and Ukraine) have a ton
of experience manufacturing airplanes (military and airliners). More recently,
Sukhoi even managed to churn out a highly competitive, well received regional
jet (the Superjet 100). Yet sales are lagging while Bombardier and Embraer
dominate that market. Reliability is almost there, but there's next to no
support. Without a support network you're dead in the water. To that end it
appears that the Russians are taking this far more seriously than I'd expect
the Chinese to. So beyond just manufacturing the part, there are cultural
issues to overcome.

The Japanese are another example. Most people in this thread probably hold
Japanese manufacturing in high regard (and for good reason). However, take a
look at Mitsubishi. They're attempting to get in on the regional jet market as
well. However, they're basically dead in the water and may end up scrapping
the whole project. While there is a Japanese aviation industry, and Boeing
partners heavily with some Japanese companies, the Japanese have never built a
jet airliner and airliners are simply that complex.

So, sure, we'll eventually see more Chinese cars and higher quality Chinese
consumer electronics. Sooner than later even. Aviation stuff? Maybe, but
potentially not in my lifetime.

~~~
cauldron
Passenger jet is not only a matter of wether you can produce it, what's most
important is wether it's cheap to fly, otherwise no one other than Chinese
state airliners would buy it.

------
nkurz
As someone concerned by what often seem like excessive legal obstacles to
doing business in the US, I thought the author made a good point here:

 _Although lawyers get blamed for a lot in U.S. aviation, I am going to make
the case that you don’t get to see the good that they actually do. Putting
emotion aside, think about this: Every year, countless people from outside of
aviation refuse to sell products to, or work with, aircraft builders, citing
the reason, “I don’t want to get sued.” Some of these people make good stuff
that could be well used in experimental aviation. But a number of them make
trash, or things that are not appropriate for planes, many of them have no
idea of how aircraft work, and most of them have never even flown in a light
plane. If those people make stuff for planes, and claim that their stuff is
airworthy, they would get sued._

~~~
FlyMoreRockets
And sometimes, good aviation companies get sued for the actions of their
customers.

Vans Aircraft is a large, successful kit plane manufacturer. More new home
built Vans airplanes fly each year than new Cessnas (or probably any other
current aviation company, for that matter).

Prior to Vans amazing success, it was common for kitplane companies to run
very lean and turn the whole company over (or liquidate the assets and turn
them over) in the event of a lawsuit, thus avoiding an expensive legal fight.

A Vans airplane was involved in a double fatality. Even though the NTSB
determined the pilot to be doubly at fault, a $35 million lawsuit was allowed
to proceed in the US. Vans had to provide a legal defense. The lawsuit was
eventually dismissed, but doubtless Vans was out a lot of money, both the
years of legal defense and bad PR.

[https://www.reuters.com/article/us-north-carolina-
lion/lion-...](https://www.reuters.com/article/us-north-carolina-lion/lion-
kills-young-worker-at-north-carolina-wildlife-sanctuary-idUSKCN1OU00I)

[https://newsline.kitplanes.com/2015/10/20/vans-aircraft-
sued...](https://newsline.kitplanes.com/2015/10/20/vans-aircraft-sued-
for-35-million-over-rv-10-crash/)

[https://newsline.kitplanes.com/2017/02/22/lawsuit-against-
va...](https://newsline.kitplanes.com/2017/02/22/lawsuit-against-vans-
aircraft-dismissed/)

~~~
jcoby
The discussion over at the VAF is enlightening as well [1]. The guy basically
ignored everyone around him and decided to do things his way or incompletely
(he was flying with clecos in the fuselage). That combined with get-there-itis
and inexperience with the plane led to his death.

I've flown an RV10 and and seriously looking into building one. Nothing about
his accident has any influence on my decision process. The Vans kits are
probably the best in the industry and section 5.27 of the plans clearly says
not to use any sealant, including RTV, on fluid fittings. (Section 5 is a
common chapter to all of the RV series and even comes with the practice kit.)

1\.
[http://www.vansairforce.com/community/showthread.php?t=44934](http://www.vansairforce.com/community/showthread.php?t=44934)

PS your first link is about lions.

~~~
mcguire
" _PS your first link is about lions._ "

That may be my fault. That story ([https://www.reuters.com/article/us-north-
carolina-lion/lion-...](https://www.reuters.com/article/us-north-carolina-
lion/lion-kills-young-worker-at-north-carolina-wildlife-sanctuary-
idUSKCN1OU00I)) seems to be following me around today.

------
Waterluvian
I've developed this notion that there's people out there who think there's a
trick or shortcut that nobody else knows and that's what's going to make them
rich. Buying from the wrong suppliers in China seems to be a very common thing
these kinds of people do.

I guess part of the problem is that get rich quick schemes do sometimes work,
providing a false signal to others.

~~~
morganvachon
Yeah it's definitely a numbers game. One of the distributors I contract for
found that their upstream parts manufacturer stopped making a certain part,
and they bid on and won the rights to the design and patent. The distributor
did some research and found a Chinese (Taiwanese) manufacturer who could
manufacture them at scale, sent a sample and a CAD packet, and about two
months later received a 100 piece sample set for QA to go over. Every piece
passed QA testing flawlessly, and was nearly indistinguishable from the
original part. They placed an order for 400 more parts, and when those came in
about one in four had issues making it inoperable. The quality control on the
purchased, final product was horrible compared to the nearly perfect samples.

As a bonus, soon after the deal was finalized they discovered a Chinese vendor
on eBay selling the (highly vertical market) part for a fraction of the retail
price, but higher than their cost with the new manufacturer. It was obvious
what was going on, but how do you sue a Chinese manufacturer who can close
shop at the first sniff of lawyers and reopen six months later under a new
name? They have the designs so they may as well own the IP, at least in China.

These are the kinds of mistakes a small business makes when trying to gamble
and cut corners.

------
chayesfss
Long time vair enthusiast (4wheel), I’ve known about the use of these motors
in aircraft for a long time. Crazy to think anyone would want to put a chinese
crank in one till you realize that they go for 3-4K? No wonder someone was
trying to drive costs down. Wonder where Clark’s get their cranks.

~~~
itomato
$3K gets you a crank for a niche application advertised as "the finest Corvair
crankshaft available, showcasing meticulous attention to detail and surface
finish".

A (reground) 50-year old cast crank sounds like a poor substitute in aviation
applications.

~~~
justin66
How much risk is involved in regrinding? A part that has performed adequately
for fifty years doesn't necessarily sound like an unsafe choice.

~~~
itomato
"adequate performance" in a dubious early 1960's automotive application isn't
the starting point for adequate performance in a 2010's airframe.

Not to mention the material differences between a machined billet crank and
part cast in sand five decades ago, subsequently salvaged and reworked.

------
jandrese
> This is when he discovered that the rod throws on the crank were ground
> almost 1/8″ too wide.

In precision machining where tolerances are typically measured in thousandths
of an inch that's way beyond unacceptable. At this point trying to make it
work is throwing good money after bad. The fact that he didn't even realize it
until he was trying to fit it into an engine means he did no QC on his own
too. This whole endeavor was destined to fail from the start. He seriously
needed a business partner with actual manufacturing experience.

~~~
zrobotics
It's even worse than that--a bearing surface on a crank journal will be
specced in ten-thousandths if an inch (~2 \u m). Width of the journal isn't
typically as precisely specced, but for an aircraft motor journal width is
extremely important, as the crankshaft is placed under high thrust loadings.
While there will be a thrust bearing, crank endplay on an aircraft motor is
even more critical than on an automotive engine.

I have no sympathy for the businessman who had the cranks made, something that
far out of spec should have never made it into a customer's hands. If you are
serious enough to invest 30k in tooling to get parts made, you should also be
consulting with an experienced engineer and lawyer who both have experience
dealing with Chinese suppliers.

~~~
solotronics
Even more dangerous was that he was selling cast cranks as billet. Without
doing x-ray good luck finding occlusions in a Chinese part. It could look fine
and even measure out fine (these did not thank God) but have bubbles within
the casting.

There is a reason forged and billet American performance car parts are
expensive!

There is a huge amount of testing, engineering, and quality control that goes
into a crank made by Bryant or Callies.

~~~
WalterBright
A forging is about 3x the strength of the equivalent casting with the same
metal.

I put all forged moving parts into my Dodge engine build :-) It wasn't
strictly necessary for the power levels, but what the hell.

But I did get a forged scattershield, because I like my feet.

------
thrifter
Reminds me of the "shaft passer": [https://medium.com/@jasoncomely/the-
perplexing-shaft-passer-...](https://medium.com/@jasoncomely/the-perplexing-
shaft-passer-d3c71b015a04)

------
fest
I have seen the product development and manufacturing processes in one of the
Chinese sites of the second largest CM in the world. They sure know how to
develop and build products no worse than any other nation. On the other hand,
I've worked with a factory there which cuts corners at every opportunity (the
path of least resistance) and requires someone on ground to communicate what
is the expected end result.

~~~
tabtab
Most parts suppliers to safety-critical products have been in business for a
while and have established a culture and internal checks-and-balances to
ensure quality. It takes time to build up such a reputation and known-how to
demonstrate to customers that their internal processes ensure quality. You
can't just claim it's "good", you have to show it's good from start to finish.
Reputation is hard to gain and easy to lose.

China's industry is relatively new, and may not yet have gotten to this stage
yet.

------
dwyerm
It is interesting to hear that, what I had assumed was strictly an electronics
issue, occurs in other industries as well.

I recently read Andrew "bunnie" Huang's book "The Hardware Hacker", where he
talks extensively about building electronics in China, and it sounds very
familiar to this. Despite some problems with counterfeit SD cards, he
eventually brought the Chumby to market.

So, it sounds like you _can_ get great results and low prices, but you have to
be able to keep your eyes on the process the whole way through, or find people
you can trust who do.

But if you get it wrong, you get to write a story like Keyboard.io[1], as we
discussed previously[2].

[1]
[https://blog.keyboard.io/post/181333242149/december-2018-a-s...](https://blog.keyboard.io/post/181333242149/december-2018-a-startling-
discovery)

[2]
[https://news.ycombinator.com/item?id=18692244](https://news.ycombinator.com/item?id=18692244)

------
nimbius
Im an automotive mechanic by trade for a chain of shops in the midwest. The
point to clarify in this article I think is that cast vs billet crankshafts
are almost a pointless argument outside of classic car enthusiast communities,
or race communities.

>Brady finds out that new forged cranks can be made for about $1000.

Bull shit, and I bet he knew it too. China can cost-cut some manufacturing by
shifting the prices to human labor, but they cant drop the price on precision
machining. Every US manufacturer I know who cuts cams or cranks is feeding
billet stainless or billet high nickel into a 5 axis CNC. If its a big enough
customer, they'll ship that part to another machinist to have them QC things
like center-process and calculated c(pk) ratios.

>Compression dropped off, and an inspection showed that the exhaust valves
were bent. Usually the only thing that can do this is putting the cam in
several teeth off, something a lifelong motorhead like Steve isn’t likely to
do.

Chinese manufacturing has about as much trustworthiness in it as the chinese
communist party. Which is to say, im not surprised to see hidden rework on
this part that caused a failure. heat-treated composite Steel is not cheap in
china, so the pressure to rework is enormous. Whereas in the US we throw out
NG spec pieces on the daily, an NG spec crankshaft at a thousand dollars is
valuable enough to feed an entire village for the week.

>In the end, the Chinese kept all his money, he lost his business, his house,
and a lot of the other things in his personal life unraveled.

speaking from experience, the chinese are just now getting around to
manufacturing tooling that can withstand more than a few drops in the
toolchest. high speed steel parts for example are still prone to fracture at
ridiculously high rates. chinese fasteners are spot-on clones of german and
american fasteners, but fail at much lower levels of force. Even the steel
stamped to make bolts, cotter pins, and collars is riddled with QC variances
and imperfections that can cause a part to fail in hours.

~~~
rdtsc
> I think is that cast vs billet crankshafts are almost a pointless argument
> outside of classic car enthusiast communities, or race communities.

It is an aviation community in this case as well. They are re-purposing a car
engine. It seems the loads on the crankshaft if it is directly attached to the
propeller will be quite different that what the would be in a car. With a
propeller there would be a bending component (propeller acting a gyroscope)
besides the twisting component, especially when say doing aerobatics, while in
a car the it will be mostly a twisting component.

So perhaps then cast vs billet becomes more important as one can withstand
bending forces better than the other generally.

~~~
jcims
Don't most props drive off a gearbox? Wouldn't that soak up most of the
bending forces?

~~~
sokoloff
Most (probably 99+% of them) piston airplanes are direct drive, meaning the
prop hub is directly bolted to the crankshaft flange as can be seen in the
last photo in the linked article.

Cessna 421 is one of the common geared engine aircraft. Twin Bonanza, Navion,
late Widgeons, R985s, and others also have geared engines, but they’re the
vanishingly small minority of piston aircraft.

Common types (Cessna 172/182/210, Beechcraft Bonanza/Baron/Skipper, Piper
Cub/Warrior/Arrow/Seminole/Seneca/Apache) are all direct drive.

~~~
jcims
Cool! I had always thought they were direct drive, it makes sense to go that
route. But then I started noticing gearboxes in various videos to the point
where i switched my thinking.

------
bane
There's a word for the inexplicably poor material that otherwise visibly
identical Chinese components are made from "Chinesium". I'm sure it will
eventually be viewed as some kind of slur.

The good news is that the quality of Chinese goods is rapidly improving, if
anybody remembers the absolutely rock bottom quality of Chinese made good 30
years ago, the products are absolutely improving. It's just that the rest of
the world is working at such a level of quality that Chinese-made goods just
aren't quite there yet.

Just wait for Chinese society to catch up and I have no doubt that in 30 more
years "Chinesium" will represent some kind of unobtainable praiseworthy
material that nobody else can seem to make.

------
RickJWagner
I'm amazed that Corvair engines are being put into airplanes. Wow, the Corvair
went out of production in the 1960s!

I'm a little happy about this-- longevity of use, the same materials being re-
used for decades. I'm just surprised.

~~~
2sk21
Exactly - I am amazed that Corvair engines can be made airworthy!

~~~
mcguire
It makes sense: they're higher displacement and air-cooled.

------
Zhenya
Here's what I don't understand (aside from the naivete of Brady):

What percentage of the aircraft cost is the delta between the Chinese and US
made crank? 2k/80k? Does even make sense to cut corners here? For rotational
and safety critical items I always use OEM or better in my street cars, what
would drive aviators to not think the same?

~~~
zrobotics
For these engines, the only new option is the type of custom-made billet crank
normally only seen on high-level drag engines or Bonneville cars. Otherwise, a
(inspected) used crank is installed. But for something like a crank, to try to
farm it out to a Chinese supplier with no oversight is insane.

------
ruslan_talpa
Slightly related question about chinese products and their quality. I am
planning on buying (from china) a flatbed food printer based on epson print
head. Is it a good idea? It’s about 2k.

Anyone know a us/eu manufacturer that makes/sells them (i would prefer
spending 1k more in return for product quality)

------
fmajid
The phenomenon is known as “chabuduo” (good enough):
[https://aeon.co/essays/what-chinese-corner-cutting-
reveals-a...](https://aeon.co/essays/what-chinese-corner-cutting-reveals-
about-modernity)

------
mcguire
Huh. Then I learned that engines from a weird, controversial 1960s Chevrolet
are used in small aircraft.

~~~
pravda
It's because it is an air-cooled engine.

------
heyjudy
I have a friend who knocks off expensive and vintage RC ICE's in China by
casting with minimal machining. Does it more as a hobby than gray market
counterfeiting imposing on brands.

