
Kern Microtechnik: Accurate CNC Machines [video] - SQL2219
https://www.youtube.com/watch?v=Ijl6uDa_kQU
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opwieurposiu
Once you get down to below 1/1000 of an inch or so, you start to notice that
metal is really like playdough. it squishes out in all directions when you
clamp it, it springs back when you cut it. it is never exactly the same shape
after it has been handled.

Just another thing that adds to the difficulty of super high precision work.

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sansnomme
What do you use to observe such phenomenon? Optical microscopes?

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mrob
Often using a dial indicator. A rack and pinion converts the linear to rotary
motion, and gears magnify the rotary motion:

[https://en.wikipedia.org/wiki/Indicator_(distance_amplifying...](https://en.wikipedia.org/wiki/Indicator_\(distance_amplifying_instrument\))

tubalcain has a good video showing how they work:

[https://www.youtube.com/watch?v=Rp6D3YTx7iU](https://www.youtube.com/watch?v=Rp6D3YTx7iU)

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hlieberman
For a slightly more accurate CNC lathe and grinding machine (1 micron) that
can be made "at home":
[https://www.youtube.com/watch?v=sFrVdoOhu1Q](https://www.youtube.com/watch?v=sFrVdoOhu1Q)

~~~
ineedasername
Yeah, that seems to be for values of "at home" that only includes the homes of
expert CNC machinist with access to someone to write custom software for it.
Otherwise, the accuracy is impressive, though it doesn't seem to approach the
level of automation seen in the Kern machines.

~~~
jbay808
Yes, this is not any ordinary person in any ordinary home. His home also
happens to be a world class prototyping facility.

I don't think Dan is interested in more automation though. It typically only
pays off for big production runs, especially compared with how fast he is.

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kev009
I've been pretty bummed on "tech" lately because software is such a shit show
so this was impressive and inspiring, both the machines and the seeming
quality and focus of the employees.

~~~
ChuckNorris89
Yeah, everybody is rooting for advancements in hardware/mechanical until they
see the salaries this field pays.

I'm surprised the field is advancing at all seeing app kiddies can walk home
with more $.

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mysterypie
You made me curious. According to the U.S. Bureau of Labor Statistics
(bls.gov):

\- Metal and Plastic Machine Workers make $17.35 per hour or $36,080 per year

\- Machinists and Tool and Die Makers make $21.61 per hour or $44,950 per year

\- Software Developers make $50.77 per hour or $105,590 per year

Employees at a top notch company like Kern Microtechnik probably make more
than the machine worker average aboves, but then software developers at FAANG
make more than the developer average as well.

It's sometimes astonishing that there isn't more correlation between skill and
craftsmanship and how much you get paid.

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frankharv
As a machinist of 35 years I can say your pay scale is WAY off. Just look jobs
on Indeed.Com.

Trust Me, A Tool and Die Maker makes much much more than you quoted. Problem
is everybody wants to learn whizbang instead of getting a foundation of
conventional machinery.

What cracks me up is I see CNC programmer jobs paying less than Tool and Die
makers when programming requires computer knowledge.

The real problem with the trade is Vo-Tech is dead and kids can't even swing
wrenches these days, let alone the strong mental math skill required.

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thrwayxyz
Could you give hard numbers for what you would consider reasonable pay?

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jacquesm
I know a tool-and-die maker that works on high volume plastic injection molds
that makes a comfortable multiple of my salary. This is very precious
knowledge and having it can save a company many millions of dollars in re-
tooling and discarded product.

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thrwayxyz
A number would be nice.

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defterGoose
Big fan of NYCCNC, and have been anticipating this video for awhile since he
first mentioned it. Too bad it's not as in-depth as some of their other
factory tours. Clearly Kern has some secrets they're not keen on letting slip.

Check out their Starrett tour: it's one of my favorite videos on all of YT.

[https://youtu.be/T7JqXbm-Nwo](https://youtu.be/T7JqXbm-Nwo)

~~~
perryh2
Thanks. I just spent over an hour watching a variety of videos on YouTube
about CNC.

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heyalexej
Found out about them through Nick and Josh Hacko of
[https://www.instagram.com/nicholashackowatch/](https://www.instagram.com/nicholashackowatch/).
They use a wire EDM made by Kern to manufacture watch parts.

If you're into this kind of precision,
[https://www.instagram.com/robinrenzetti/](https://www.instagram.com/robinrenzetti/)
and
[https://www.instagram.com/stefan_gtwr/](https://www.instagram.com/stefan_gtwr/)
are great to follow.

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madengr
2 um accuracy; tools so fine that tool change air flow will break them;
amazing. I could use this for machining mmWave components.

~~~
colechristensen
I've been acquiring tools to fix/measure/improve cheap CNC mill and 3d
printer, the $100 dial gague I picked has 10 µm as its smallest increment, you
can just barely see a 2µm variation. The force the measurement tool imparts on
the part and its support structure is more than that.

The next steps are either carelessly blinding myself trying to build a laser
interferometer or spending a ridiculous amount of money on more precise
gagues.

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YZF
The black matrix glass in an LCD is typically accurate to a few microns since
it's made in a photolithography process. If you couple that with a
microscope/camera (e.g. mounted where your tool usually goes) you can use that
to calibrate your CNC mill across its work area with some machine vision
software. This is probably going to be a lot cheaper and simpler than using
interferometers and for any practical purpose should have better accuracy than
what you can expect to ever get out of a regular CNC mill. I'm not sure if you
can just buy those somewhere or you'd take a display apart or something along
those lines...

~~~
colechristensen
My interests are more in general purpose tools for increasing accuracy, and
perhaps using them to increase the accuracy of inaccurate tools through
feedback systems.

That is, throw out chasing perfection of rigidity, dimension, and flatness of
a mill (etc.) Instead keep adding measurement and feedback until the precision
of the machine parts doesn't matter. (or, continue to amuse myself and annoy
my partner by making messes and spending my disposable income trying)

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msds
Having tried this, with some fancy measurement tools and a pretty custom and
high-performing control systems, I've concluded that it's a route to madness.
Fancy software and feedback turn out to be a very hard way to emulate large,
straight pieces of cast iron, and there's no substitute for rigidity once you
actually start cutting - vibration is a huge issue, and very tricky to
actively damp. Essentially every machine tool that does have crazy accurate
realtime feedback (diamond turning for optics, ultra precision milling, etc)
starts with a rigid and long-term stable frame and adds the $$$ controls.

Granted, my switch over to "more rigid more better" may have gone a bit too
far - I now own a 10ee (3200lbs), and am looking for a good jig borer
(2400lbs+).

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YZF
You're right that one can't compensate for lack of rigidity with software but
you can have an inaccurate but rigid structure and compensate on top of that.
It's pretty common practice to use some sort of software compensation to
improve accuracy (at least in certain applications where it matters).

Metal milling machine need to be super rigid because of the cutting forces...
You can build super accurate machines (e.g. with granite) that can't be used
for milling but can place a tool with a (sub-)micron accuracy.

Even with metal you can take lighter cuts and trade off some rigidity for
accuracy, but then it's gonna take much longer to get anything done...

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jbay808
An inaccurate but rigid structure, unfortunately, won't hold its calibration.

Go for the jig borer, and get them while you still can. It's what Professional
Instruments does, and it's what I would do if I had space for one.

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YZF
It can. Basically a repeatable machine can be made accurate by calibration. It
doesn't have to be accurate to start with. If it's not repeatable (i.e. won't
hold its calibration) then yeah, it won't ;) But accuracy != repeatability.
I've worked on precision machinery (1um accuracy) and we used calibration
techniques.

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jbay808
This is also my field. The issue is, the machine will be repeatible on the
short term but not on the long term. It will look like it's behaving well
during calibration and the next few months of operation.

But if the ways and mating surfaces aren't almost-perfectly straight and flat,
they'll experience accelerated wear. (If you're using hydrostatic bearings,
they won't work to begin with unless the surface is accurate). Then the
calibration is gone. And that's just in the static case.

If your ballscrew has uneven pitch, is eccentric, or any number of other
issues, you can calibrate it out. But now to move at a constant speed, your
servo controller has to drive that inertia at a wobble, and everything shakes.

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YZF
The machines I worked on had air bearings. No wear. Basically we're talking
about something like an error of 10um over 2 meters. It's practically
impossible, or cost prohibitive, to remove that error without calibration. The
granite surface the air bearings ride on is _locally_ flat but not perfectly
accurate over its entire length.

I agree this setup _is_ almost perfectly straight and flat. But it's still not
accurate without the calibration.

Just to be clear, there's weren't milling machines...

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injidup
If you want to work on software in this industry then check out
[https://www.moduleworks.com/join-us/](https://www.moduleworks.com/join-us/)
Moduleworks develops algorithms for many of the CAM platforms that target
machines like KERN develops.

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nodesocket
Why is it that Germany makes the best industrial machines and industrial
manufacturing?

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ofrzeta
I am not saying they don't but in German machine shops I have worked a lot of
machines were of Japanese origin such as Okuma or Mori Seiki.

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zaarn
IIRC from when I did metal work, that's mostly because the Japanese vendors
deliver more machines per year.

German manufacturers generally don't make that many machines, one because
they're used for a _LONG_ time (I learned milling on a machine from the 60s in
2015), two because they are complicated to build. You can't easily order 100
high quality mills from a german shop.

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gundmc
Really incredible machines. Additive manufacturing has gotten all of the hype
lately because it's new and quickly developing, it's equally exciting to see
cutting edge developments in traditional subtractive manufacturing.

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SQL2219
I am burned out on software, would love to be a machinist. But I am not
interested in huge pay cut. I am thinking about building a machine shop in my
garage.

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paddy_m
I took a side job in a machine shop over the winter.I was loading parts in and
out of CNC machines, doing a little setup, cutting metal, made one fixture,
and a lot of floor mopping. I thought the manual labor was going to make me
appreciate the cushy desk job work that I normally do, but I absolutely loved
working in the shop.

I wrote an email to friends and family about, hit me up via my email in my
profile and I'm happy to share it with you.

I'm trying to find a similar part-time apprentice position in NYC where I live
now - any suggestions?

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slowhand09
I'm just disappointed that TechShop went bankrupt. At one point I wanted to
open a facility in the Balt/Washington corridor. I figured there'd be a lot of
people wanting to learn those skills, and an accessible location. They opened
a franchise in Crystal City, VA (DC) but all closed in 2018. It was a a mega-
makerspace with classes to learn all theses technologies.

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rkagerer
What do one of these machines cost? What's the "build volume"?

