Thursday, November 3, 2022

How to make precise sheet metal parts (photochemical machining)

 

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How to make etched metal parts.
-All of the highest quality parts that I made went to the customer, but edge quality and photoresist adhesion is still a problem.

-The photomask dark areas can be expanded, and then the part etched for a longer amount of time to make the edges more perpendicular to the surface. I forgot to mention this clever way to improve the etch aspect ratio called "etch factor" http://www.chemcut.net/wp-content/uploads/2015/03/Chemcut_Thoughts_on_Undercut.pdf



-Special ink and transparencies (films) for photomasks: https://filmdirectonline.com/




-Strange Parts did a great video on metal business cards: https://www.youtube.com/watch?v=83GDV0xsTTs

-https://mymetalbusinesscard.com/product/stainless-steel-business-cards/ 100 cards for $250 could be the cheapest way to get custom mechanical parts: https://www.youtube.com/watch?v=bkZkaT_P0Ck

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Sunday, September 11, 2022

High speed X-ray video: jumping beans, wind-up toys and more!

 High-speed X-ray video captured with a Dectris photon-counting detector. I show how the process works and how this detector is different than normal camera detectors. 


https://www.dectris.com/

https://media.dectris.com/Technical_Specification_PILATUS_100K-S_V1_8.pdf

Mexican jumping beans: https://www.amazingbeans.com/

X-ray timelapse video: https://www.youtube.com/watch?v=j-FHbHoiwNk

ImageJ image format converter: https://imagej.nih.gov/ij/  (the NIH's SSL cert expired?)

Flipping through images fast enough as if playing video: https://www.irfanview.com/

Video editing software: https://www.blackmagicdesign.com/products/davinciresolve/edit

The sequence of tiff files directly from the sensor contain a lot of temporal flicker -- probably because the X-ray tube itself has time-varying output.  This isn't so bad at 60Hz, but quite a problem at 300Hz.  I used Resolve's "color stabilizer" to maintain constant levels throughout a clip, and was impressed how well this removed the flicker.


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Tuesday, May 31, 2022

Drawing on a plasma display with a laser pointer

An orange plasma display will retain an image caused by incident near-UV light. This is an interesting visual combination of photoelectric, hot carrier injection, plasma, and charge trapping effects.



Correction: The orange display is running at 700Hz, 130V in the video.
  I realize that I may have conflated the issues of one-resistor-per-pixel and the display's ability to maintain an image throughout row scanning. They are separate problems that are both addressed by designing the panel to work on AC. Each pixel can maintain its state (on or off) by being supplied constantly with a lower "sustaining" voltage, and can be set or cleared by giving it a momentary higher or lower amplitude. The sustaining voltage allows the pixel to be emitting light or not, and its state remains because of its own impedance until updated on the next scan. In color plasma displays, separate electrodes are used for sustaining and addressing pixels, and the discharge may be sustained between coplanar electrodes instead of plane-to-plane, as in this display.

It's also a possibility that the dielectric and MgO layer only exists on one electrode (the metal), and the ITO is bare. I don't know. On this display, if all rows are electrically connected together, and all columns are connected together, and AC is applied to rows and columns, this effect does not work -- no light is emitted at all! At least some of the electrodes (ie every other column) must be left floating to emit any light, and to show this memory effect. So, driving AC plasma panels requires more waveform tricks that I do not fully understand.

Prior art patents: https://patents.google.com/patent/US7283301B2/en https://patents.google.com/patent/US20060132716A1/en


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Saturday, April 9, 2022

Silver nanoprisms grown into structural colors by high power LEDs



How to chemically synthesize silver nanoparticles, then grow them into triangular nanoprisms with light from a variety of LEDs. Each color LED creates a different size nanoprism, which has its own characteristic color.

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CMDITR video: https://www.youtube.com/watch?v=agD5jfXua-o 
Multispectral LED driver on Github: https://github.com/benkrasnow/MultiSpectLED 
Chemicals sourced from Amazon/eBay 
20ml glass vials with PTFE lined cap (do not use metal-lined): Environmental Express APC1675P Already gone from Amazon 
pH pen (this cost more than I remember, but it works really well, and has lasted many years. Cheaper pH pens are often pretty bad) https://www.amazon.com/gp/product/B01ESYG6B0/ 
Comparison of CD, DVD, Blu-ray discs with electron microscope: https://twitter.com/BenKrasnow/status/615327472909840385 
Great way to find related papers: https://www.connectedpapers.com/ 

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Sunday, January 9, 2022

Olestra (zero calorie cooking oil) - chemical synthesis and taste test



I synthesized olestra from biodiesel, sugar, and soap with a sodium metal catalyst. I also describe some of the history of olestra's development.







Procedure that I used (Example 1) https://patents.google.com/patent/US3963699A/en 

Other resources: https://patents.google.com/patent/US20060047109A1/en

https://patents.google.com/patent/US4611055A/en 

https://sci-hub.se/https://doi.org/10.1021/ed068p476 

Biodiesel: https://www.e-education.psu.edu/egee439/node/684 

https://extension.okstate.edu/fact-sheets/biodiesel-production-techniques.html 

https://www.youtube.com/watch?v=3anau83Qxt4 

Epogee fat substitute: https://www.epogee.com/the-technology 

https://healthsmartfoods.com/products/sweet-nothings-low-fat-chocolate-covered-caramel 

Potassium oleate soap synthesis: https://lipidlibrary.aocs.org/documents/LipidsLibrary/Book%20II_ch03.pdf 

Studies on gastro distress and calorie compensation: https://sci-hub.se/https://doi.org/10.1046/j.1467-789X.2002.00050.x 

https://sci-hub.se/10.1006/rtph.1997.1164 

https://sci-hub.se/10.1001/jama.279.2.150 

Anal leakage MadTV: https://www.youtube.com/watch?v=Tx9LSEjgQxY 

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