Brass plates

 

Everybody has seen these little bras plates with type and company names on them on old radio`s and equipment. These brass ones with black inserts and fitted with a small brass screw or nail.


 

I`ve tried to refabricate these things, and the result is very good.
You need: Fotographick laquer us used for making printed circuits.
Brass sheet of a thickness of around 0,75-1mm.
UV source.
Etching material like you use for printed circuits.
 

First I made a design of the brass plate using Photoshop. "Rhamen antenne" is german for loop antenna. The design of my antenna comes from the magazine "funkbastler" from 1926. I printed the design onto overhead projector foil, this is transparant foil and can be used to expose using you UV source.

 

Then we take our piece of brass sheet, clean is very good using scotch brite or fine waterproof sandpaper. Degrease very well with thinner or alcohol. let it dry very well.
Next step is to spray the photo laquer (positiv 20), see can for instruction. Let it dry very well.

Note: Also the sides and back needs to be etch resistant, paint it with etch resistant paint or the photo laquer. As long you cannot etch these sides away.
When the laquer is dry on the brass sheet, you can expose it to your UV source like you do with your circuit boards.


After you exposed it the brass sheet needs to be developed, here I use the same thing is for my printed circuit boards.

Clean very well using water,..do not toutch with you fingers.
Then etch the brass sheet using you etching installation, I did it with a temperature of 40ēC and a time of 45 minutes.


 

Then clean it very well, degreaser, thinner, alcohol,.... Next spray the front side with black laquer (spray can from autostore), a few layers till you do not see the etched markings. Let it dry VERY well,..(overnight)
Then take a piece of waterproof sandpaper (first 500, then 1200) on a piece of flat glass, and sand away the "high" sides of the front. (the paint stays in the lower sides).
Clean your piece, polish it and you see the result at the right.






 

 Next step was a dail for my regenerative receiver.

This time not Photoshop to create the dail, but I used Autocad (ACAD) instead, you can draw in scale 1;1 and also print it in the same scale.

 
At the right the brass sheet of 0,75mm thick after the exposure and developement, now it is waiting to be etched..



 


 

At the left you see the dail being etched, time of etching is 40 minutes at a temperature of 40ēC.

 

After etching make it the size it is intended, clean it very well and do the same  procedure as mentioned above to get the black paint inside the lower parts of the etched dail.
Inclusive needle to put onto the 1:6 vernier where also the knob is put on.

This way you get a nice looking dail with needle like the are used at the beginning of the 20th century.

 


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PA2MRXŠaug-2008