Beauty of old electrical and measuring things, etc.

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dlgoff

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Here, the beauty is in "system's" reliability. After hundreds of pump-downs, never a component failure.
No matter how reliable rotary vacuum pumps are, they still need maintenance. One of my Edwards 8 dual stage pumps started to perform below expectations, so it's time for a clean and overhaul.

Here, the beauty is in the interior parts.

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Oh BTW. Vacuum pump oil makes it a really messy job. :oldruck:
 

dlgoff

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A restauration master at work
Just goes to show that restorations are no easy matter. Now you've got me wanting an old micrometer.
 

davenn

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A restauration master at work
I kinda disagree with filing off of the casting ridges and filling on of hollows ( unless the hollows were caused by damage). Those ridges and hollows are part of the originality of its creation and now its uniqueness has been lost :frown:


Just goes to show that restorations are no easy matter.
yeah, it helps to have the right tools to do the job
 

DrClaude

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I kinda disagree with filing off of the casting ridges and filling on of hollows ( unless the hollows were caused by damage). Those ridges and hollows are part of the originality of its creation and now its uniqueness has been lost :frown:
I agree. He does that in all similar restorations, but I think he should only repair damage.


yeah, it helps to have the right tools to do the job
And the talent!
 

jim hardy

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Takes patience and manual dexterity.

My old friend Harry and a fiddle restoration in progress.
Note home made fiddle clamps - old sewing thread spools work well.

244989


Difference between a fiddle and a violin ?
Violins don't get beer spilt on 'em.
(@dlgoff that's your Grandma's violin)

sorry ths one's off topic, being not electrical..

old jim
 

dlgoff

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Takes patience and manual dexterity.

My old friend Harry and a fiddle restoration in progress.
Note home made fiddle clamps - old sewing thread spools work well.

View attachment 244989

Difference between a fiddle and a violin ?
Violins don't get beer spilt on 'em.
(@dlgoff that's your Grandma's violin)

sorry ths one's off topic, being not electrical..

old jim
Thanks for posting this photograph @jim hardy. I was going to post it here once I got your permission but just hadn't gotten around to asking you.
 

dlgoff

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My old friend Harry and a fiddle restoration in progress.
Harry did a great job putting this violin back together after all the abuse I gave it as a kid.
sorry ths one's off topic, being not electrical.
But the waveforms a violin produces is just as complicated as electrical analog signals. Years ago, after my school's EE department invited Robert Moog to explain the electronics of the music synthesizer he designed and built, I played around making analog circuits that "duplicated" string instruments. IIRC a violin's waveforms are rich in odd harmonics.
Anyway, here's that old violin now.
245059
 

jim hardy

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IIRC a violin's waveforms are rich in odd harmonics.
They're interesting also from a mechanical perspective.
The front and back vibrate in various modes, not just as a simple sheet
a wood soundpost about the diameter of a pencil is placed right underneath the 'bridge' to mechanically couple couple them,
and a 'bass bar' stiffens the front to help it produce low notes,
as you can imagine the varying thickness of those front and back plates controls the sound of the fiddle.
Yours was well made. The neck mount was unusual, similar to that of a region in the way northeast of Germany. Harry liked its tone and said whoever thinned its front and back knew what he was doing..

Theory of vibrating plates is an interesting niche
https://www.phy.davidson.edu/StuHome/derekk/Chladni/pages/history.htm said:
History of Chladni's Law
f ~ (m+2n)^2
The story behind the equation:
Ernest Florens Friedrich Chladni of Saxony is often respectfully referred to as "the Father of Acoustics". Indeed, his body of work on the vibration of plates has served as the foundation of many experiments by countless other scientists, including Faraday, Strehlke, Savart, Young, and especially Mary Desiree Waller. Chladni's study consisted of vibrating a fixed, circular plate with a violin bow and then sprinkling fine sand across it to show the various nodal lines and patterns. The experiment is particularly rewarding in that high frequencies often exhibit strikingly complex patterns (see the pictures on the image page). In fact, Chladni's demonstrations in many royal academies and scientific institutions frequently drew large crowds who were duly impressed with the aesthetically sophisticated qualities of vibrating plates. Napoleon himself was so pleased with Chladni's work that he commissioned the further study of the mathematical principles of vibrating plates which then spurred a plethora of research in waves and acoustics. While experimental methods and equipment have been much improved in the last 200 years, Chladni's law and original patterns are still regularly employed to study plate vibrations.



References:
Rossing, Thomas D. "Chladni's Law for Vibrating Plates." American Journal of Physics.Vol 50. no 3. March, 1982.
see also

I hope your grandchildren enjoy it as much as you did..
 

dlgoff

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They're interesting also from a mechanical perspective.
The front and back vibrate in various modes, not just as a simple sheet
a wood soundpost about the diameter of a pencil is placed right underneath the 'bridge' to mechanically couple couple them,
and a 'bass bar' stiffens the front to help it produce low notes,
as you can imagine the varying thickness of those front and back plates controls the sound of the fiddle.
Yours was well made. The neck mount was unusual, similar to that of a region in the way northeast of Germany. Harry liked its tone and said whoever thinned its front and back knew what he was doing..

Theory of vibrating plates is an interesting niche


see also

I hope your grandchildren enjoy it as much as you did..
Thanks for these references Jim. And thank Harry for his expert restoration.
I hope this fiddle will be passed down for generations.
 

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