Published On Jan 23, 2022
This is the fourth in a series of videos covering the repair and restoration of a WW2-era SCR-284 radio set. In this video, I fabricate a replacement nameplate for the radio set's hand-crank generator.
Warning: all dimensions, quantities, and process times are approximate. Work with chemicals and tools at your own risk. Always wear protective equipment and dispose of waste properly. Do not attempt without professional supervision.
Process details:
1. Laminate a piece of 20 gauge zinc plate with dry film photoresist.
2. Mask with artwork transparency (recommend two identical laser printed layers), then expose for 2 minutes to a 6W UV light fixture at a distance of about 18in.
3. Remove clear protective layer of film, then place exposed plate into a solution of 6g washing soda and 200mL water. Develop for 3 minutes 15 seconds, with periodic gentle agitation of the plate surface by gloved fingertip. Rinse plate thoroughly.
4. Cover unmasked sections of plate with tape, then etch in a solution of 25g copper sulfate pentahydrate and 200mL water for 22 minutes, with periodic gentle scrubbing by a toothbrush. Rinse thoroughly.
5. Remove tape and immerse plate in a solution of 10g lye and 200mL water until the photoresist is released. Rinse thoroughly. Take precautions to avoid chemical burns from lye.
6. Cut to shape and drill mounting holes.
7. Paint as desired. Avoid using alkyd-based paints on zinc.
8. Sand raised sections to remove paint and expose bare metal. Optionally, apply a vinyl mask to the painted area to prevent it from being scratched during sanding.
9. Stamp serial number, then coat with amber shellac to emulate WW2-era MFP coating.
10. Weather and age as desired.
Materials:
Stock - https://www.rotometals.com/030-zinc-s...
Dry film photoresist - https://www.amazon.com/gp/product/B07...
Exposure lamp - https://www.amazon.com/gp/product/B07...
Paint - https://www.montanacolors.com/en/prod...
Shellac - https://www.rustoleum.com/product-cat...
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See https://github.com/wartimeworkshop/BC... for custom hardware plans.
Music:
Piano Sonata No. 11 in A major, K. 331, III. Alla turca - Wolfgang Amadeus Mozart
Recording by Garsų Menė (https://audiojungle.net/user/garsumene)
Acknowledgements:
G503 Military Vehicle Forum - https://forums.g503.com/ - special thanks to user "g504" for providing historical reference photographs
NYC CNC - • How to Make Ink Fill Brass Machine Pl...
Gogo:Tronics - https://sparks.gogo.co.nz/dry-film-ti...
Jackson's Art - https://media.jacksonsart.com/pdf/Etc...
Friedhard Kiekeben - https://www.nontoxicprint.com/etchzin...
Tiger Lily Press - http://tigerlilypress.org/2011/01/exp...
K4CHE's Website - http://www.k4che.com/SCR-284/SCR-284%...
N6CC's Website - https://www.n6cc.com/scr-284-radio-set
Radionerds SCR-284 entry - https://radionerds.com/index.php/SCR-284
Scanned user manuals - http://www.radiomanual.info/
MicaMold capacitor restuffing instructions - https://antiqueradios.com/forums/view...
Carl's M37 Website - https://web.archive.org/web/202105132...
[EDIT: Carl has updated his website to include a reference to the channel. Thank you so much, Carl, for your kind words and involvement in the community!]
00:00 - Intro
00:14 - Artwork Capture
00:42 - Photoresist
01:13 - Etching
01:52 - Metalwork
02:17 - Color Fill
02:37 - Stamping & Coating
02:51 - Installation
Made in 2022 by Wartime Workshop.