crushed walnut shells and Tek 500 series scopes


ditter2
 

Dennis – I hope you don’t consider this off topic. It is not on repairing a classic Tek scope – but an aspect on how they were made.

After reading the posting from the Peter Keller on the Coketron, it reminded me of another unique Tek process few know of, which I would like more details on The process is “sandblasting scopes with crushed with crushed walnut shells”.

Those who have seen the insides of any 500 series era Tek scope know the beauty of the ceramic strip construction hidden under the covers. The passive components and wiring harness are interconnected on a series of ceramic strips, with notches each containing a shiny fillet of silver bearing tin-lead solder. Have you ever wondered how Tek removed the solder rosin from the ceramic strips after assembly? There is no rosin showing on the ceramic strips, unless the scope has been repaired after it left the factory.

The solder rosin was removed from the ceramic strips with an air propelled abrasive cleaning method using – crushed walnut shells. It is similar to sand blasting, but with higher volume, lower pressure and lower velocity air. I was never able to see this in action while I worked at Tek, but many of the older engineers I worked with attested to the use of this process. (When I joined in 1978, Tek was still finishing up producing the last remaining type 1A1 plug-ins for a large long term contract with the US Army. I toured the production area, but did not see the cleaning operation at the time.) I know that the Tek Materials catalog had a Tek part number listed for crushed walnut shells used for this purpose. I was told that some delicate components, such as the beam lead Tek made TDs, special rubber covers were placed over the component prior to cleaning to prevent the lead being cut by the blast.

As I have never seen the operation, perhaps another member who has can answer these questions:
What was the size of the blast gun / nozzle?
How were the crushed shells removed from the scope after cleaning – vacuum cleaning?

Steve


Roy Thistle
 

On Fri, Jan 15, 2021 at 11:28 PM, ditter2 wrote:


sandblasting scopes with crushed with crushed walnut shells
There are different "media" used in "sandblasting booths:" glass beads, silicon carbide, steel shot, aluminum oxide... and walnut shells.
Media usually come in grades... from fine to coarse. You can get walnut shells in 8/12, 30/100 and so on.
Walnut shells are called "soft shot"... but, you can still strip top coat paint with them.
The walnut shells are usually black walnut... of which the U.S. has a great preponderance: black walnut grows wild... and the nut is very hard to crack... so there are lots of them that never get hulled... and can be processed into grit.
Usually the media/shells are mostly blown away inside the booth... for reuse... after it impacts on the item being cleaned. (There is a lot of circulating air, in most booths.)


-
 

FWIW, My father was a licensed commercial ammunition reloader and he used
ground walnut shells to clean fired brass (in a cement tumbler!). Sand was
too sharp and abrasive and would scratch the brass badly but walnut hulls
gave a brilliant polished finish. He bought ground walnut hulls in large
bags that weighed about 50 pound each and like those that seed and grain
used to come in.

On Sat, Jan 16, 2021 at 10:17 AM Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

On Fri, Jan 15, 2021 at 11:28 PM, ditter2 wrote:


sandblasting scopes with crushed with crushed walnut shells
There are different "media" used in "sandblasting booths:" glass beads,
silicon carbide, steel shot, aluminum oxide... and walnut shells.
Media usually come in grades... from fine to coarse. You can get walnut
shells in 8/12, 30/100 and so on.
Walnut shells are called "soft shot"... but, you can still strip top coat
paint with them.
The walnut shells are usually black walnut... of which the U.S. has a
great preponderance: black walnut grows wild... and the nut is very hard to
crack... so there are lots of them that never get hulled... and can be
processed into grit.
Usually the media/shells are mostly blown away inside the booth... for
reuse... after it impacts on the item being cleaned. (There is a lot of
circulating air, in most booths.)






Mlynch001
 

On Sat, Jan 16, 2021 at 10:16 AM, - wrote:


FWIW, My father was a licensed commercial ammunition reloader and he used
ground walnut shells to clean fired brass (in a cement tumbler!).
I reload my own ammunition here. I use ground corn cobs and walnut shells in a vibratory polisher to clean and polish empty cases. These both do not erode the base material and leave a beautiful polished finish on the cases. I also use a very good hand cleaner which contains ground walnut shells. Easy on the hands and cleans like crazy. There are all sorts of less aggressive cleaning methods out there.

--
Michael Lynch
Dardanelle, AR


-
 

Michael,

Where do you get hand cleaner that uses walnut shells? I'd like to try
it, I used to use Lava soap with pumice, it works good but I can't STAND
the perfume that they put in it.

On Sat, Jan 16, 2021 at 11:31 AM Mlynch001 <mlynch002@gmail.com> wrote:

On Sat, Jan 16, 2021 at 10:16 AM, - wrote:


FWIW, My father was a licensed commercial ammunition reloader and he used
ground walnut shells to clean fired brass (in a cement tumbler!).
I reload my own ammunition here. I use ground corn cobs and walnut shells
in a vibratory polisher to clean and polish empty cases. These both do not
erode the base material and leave a beautiful polished finish on the
cases. I also use a very good hand cleaner which contains ground walnut
shells. Easy on the hands and cleans like crazy. There are all sorts of
less aggressive cleaning methods out there.

--
Michael Lynch
Dardanelle, AR






-
 

FWIW we tried corn cobs but they were too soft and didn't clean very well
and they also physically broke down *very* quickly and then you had to
clean up the powdery residue.. Corn cobs would clean off the dirt but it
wouldn't take the stains off of the brass. Walnut hulls would make the
brass look like new, inside and out. We threw everything into a cement
tumbler and just let it run night and day for about three days.

On Sat, Jan 16, 2021 at 11:31 AM Mlynch001 <mlynch002@gmail.com> wrote:

On Sat, Jan 16, 2021 at 10:16 AM, - wrote:


FWIW, My father was a licensed commercial ammunition reloader and he used
ground walnut shells to clean fired brass (in a cement tumbler!).
I reload my own ammunition here. I use ground corn cobs and walnut shells
in a vibratory polisher to clean and polish empty cases. These both do not
erode the base material and leave a beautiful polished finish on the
cases. I also use a very good hand cleaner which contains ground walnut
shells. Easy on the hands and cleans like crazy. There are all sorts of
less aggressive cleaning methods out there.

--
Michael Lynch
Dardanelle, AR






Phillip Potter
 

This would explain how a piece of shell came to be inside my latest acquisition, a Tek 310 ser#94... thanks for this!

Phil

On 1/15/2021 11:28 PM, ditter2 via groups.io wrote:
The solder rosin was removed from the ceramic strips with an air propelled abrasive cleaning method using – crushed walnut shells.


Greg Muir
 

There are good examples on the web where walnut shells are used in blasting applications. For example:
https://www.finishingsystems.com/abrasives/walnut-shells/

If you are really curious even Home Depot and other big box stores has bags of the blast media. I primarily use the media for removing rust and corrosion from chassis and such. Cleanup is simple using compressed air. Since walnut media does not absorb moisture it will not stick to most items.

As for the hardness of black walnuts, I have a tree in my back yard that produces a hundred pounds or more of drupe each year. The nut is a delicacy for the squirrels and it is amazing how they can grind their way through to get to the tiny amount of nut meat inside. The down side is as the squirrels gnaw their way through the nut it leaves a small rock hard object with razor sharp edges that is a delight to step on when walking around in your bare feet.

Greg


Stephen Hanselman
 

They also used to throw them in jet engine intakes to polish the blades.

Regards,

Stephen Hanselman
Datagate Systems, LLC

On Jan 16, 2021, at 08:16, - <rrrr6789@gmail.com> wrote:

 FWIW, My father was a licensed commercial ammunition reloader and he used
ground walnut shells to clean fired brass (in a cement tumbler!). Sand was
too sharp and abrasive and would scratch the brass badly but walnut hulls
gave a brilliant polished finish. He bought ground walnut hulls in large
bags that weighed about 50 pound each and like those that seed and grain
used to come in.

On Sat, Jan 16, 2021 at 10:17 AM Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

On Fri, Jan 15, 2021 at 11:28 PM, ditter2 wrote:


sandblasting scopes with crushed with crushed walnut shells
There are different "media" used in "sandblasting booths:" glass beads,
silicon carbide, steel shot, aluminum oxide... and walnut shells.
Media usually come in grades... from fine to coarse. You can get walnut
shells in 8/12, 30/100 and so on.
Walnut shells are called "soft shot"... but, you can still strip top coat
paint with them.
The walnut shells are usually black walnut... of which the U.S. has a
great preponderance: black walnut grows wild... and the nut is very hard to
crack... so there are lots of them that never get hulled... and can be
processed into grit.
Usually the media/shells are mostly blown away inside the booth... for
reuse... after it impacts on the item being cleaned. (There is a lot of
circulating air, in most booths.)









 

Hi Steve,
All of your contributions to TekScopes are, by definition, not off topic. If anything, I regret that you don't have the time to contribute more often.

All that I know about observing the private lives of electrons as they do so many unexpected things is a direct result of the oscilloscopes you and your fellow Tek engineers developed. I have been the beneficiary of many contributions you made to the instruments, patents, and trade secrets Tek developed.

I spent so many years working on aerospace products, recording studio products, and MEMS products assembled in clean room conditions that I forget they all need to be spotless. But it never crossed my mind how Tek cleaned their instruments. Until now I always assumed they never needed to be cleaned. I realize how stupid that sounds since all traces of grease. Flux, and later in my career, infinitesimal particles had to be completely removed.

I tested each of the MEMS chips I worked on in one company thoroughly for any sign that something got inside them with a PIND (Particle Impact Noise Detection) test. (https://www.youtube.com/watch?v=OL4zGxDrQXE, the fun starts at 1min, 40Sec into the video). From the perspective of an integrated circuit this is a brutal test but since our MEMS accelerometers were used by the army to test ballistic shells this was required.

Air propelled crushed walnut shells are used to clean many other things like automobile intake manifolds and valves, jet and turbine aircraft engines, bronze sculptures, and even boat hulls.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of ditter2 via groups.io
Sent: Friday, January 15, 2021 11:28 PM
To: TekScopes@groups.io
Subject: [TekScopes] crushed walnut shells and Tek 500 series scopes

Dennis – I hope you don’t consider this off topic. It is not on repairing a classic Tek scope – but an aspect on how they were made.

After reading the posting from the Peter Keller on the Coketron, it reminded me of another unique Tek process few know of, which I would like more details on The process is “sandblasting scopes with crushed with crushed walnut shells”.

Those who have seen the insides of any 500 series era Tek scope know the beauty of the ceramic strip construction hidden under the covers. The passive components and wiring harness are interconnected on a series of ceramic strips, with notches each containing a shiny fillet of silver bearing tin-lead solder. Have you ever wondered how Tek removed the solder rosin from the ceramic strips after assembly? There is no rosin showing on the ceramic strips, unless the scope has been repaired after it left the factory.

The solder rosin was removed from the ceramic strips with an air propelled abrasive cleaning method using – crushed walnut shells. It is similar to sand blasting, but with higher volume, lower pressure and lower velocity air. I was never able to see this in action while I worked at Tek, but many of the older engineers I worked with attested to the use of this process. (When I joined in 1978, Tek was still finishing up producing the last remaining type 1A1 plug-ins for a large long term contract with the US Army. I toured the production area, but did not see the cleaning operation at the time.) I know that the Tek Materials catalog had a Tek part number listed for crushed walnut shells used for this purpose. I was told that some delicate components, such as the beam lead Tek made TDs, special rubber covers were placed over the component prior to cleaning to prevent the lead being cut by the blast.

As I have never seen the operation, perhaps another member who has can answer these questions:
What was the size of the blast gun / nozzle?
How were the crushed shells removed from the scope after cleaning – vacuum cleaning?

Steve







--
Dennis Tillman W7pF
TekScopes Moderator