Instrument Knobs and Pointers

A forum for you to share and receive advice/guidance on your new radionics projects.
DocThom
Posts: 18
Joined: Fri Jul 01, 2011 8:58 pm

Instrument Knobs and Pointers

Postby DocThom » Mon Jul 04, 2011 3:43 am

Hi, all!

There is a discussion that says the knob and pointer on a radionic instrument should be connected to the .25 shaft of the variable air capacitor or potentiometer. I have recently begun using this method to secure this connection. First off, I use knobs from Antique Electronic Supply @ http://www.tubesandmore.com.. The part number is P-K374. This is a large knob with space under the base; cost $1.40 each plus shipping.

I cut a 1 inch copper disc out of sheet copper and this disk fits under the base of the knob. Using a fine gauge drill three pairs of holes are drilled from the center hole out to the edge of disk. I loop copper wire through these holes to secure the needle I use as a pointer. I look for fine beading needIes around 2.5 inches long at Michael's or other craft shops. I wrap the needle with fine copper wire for .25 inch, then slide the needIe through the copper loops on the copper disk. I then pull the wire tight and solder the needle in place after assuring it protrudes the correct length. I then drill and tap a 4/40 thread hole into the knob base along side the .25 inch brass insert so that the tap will cut a partial thread into the outside surface of the brass insert. The disk is then secured to the base of the knob with a 4/40 X 3/8 inch machine screw. This provides a secure connection between the pointer and the shaft. Here are some pic's:

[img]
Copper%20Drilled%20Plate.jpg
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[img]
Copper%20plate%20and%20pointer%20installed.jpg
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[img]
Finished%20knob%20and%20pointer.jpg
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So - there you have it. This is a great pointer for fine tuning.

Happy instrument building to all who venture to do so. Doc
Attachments
Finished knob and pointer.jpg
Finished Knob and Pointer
Finished knob and pointer.jpg (19.09 KiB) Viewed 2326 times
Copper plate and pointer installed.jpg
Copper plate installed on base of knob and screwed along side brass insert
Copper plate and pointer installed.jpg (18.29 KiB) Viewed 2326 times
Copper Drilled Plate.jpg
Copper plate drilled
Copper Drilled Plate.jpg (10.4 KiB) Viewed 2326 times

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sorynzar
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Joined: Mon Mar 01, 2010 5:41 pm
Location: Cambridgeshire, UK
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Re: Instrument Knobs and Pointers

Postby sorynzar » Mon Oct 31, 2011 6:14 pm

Thank you for posting these. I seem to have missed them, for some reason. The pin/shaft connection is a good idea. I believe some people use clock hands in place if the pin, and solder them directly to the inside of the knob.


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