I found an interesting and enjoyable article about analog tuning methods here: https://drive.google.com/file/d/1QpsnVZoIx0WZYqWHiVsQWWDgv3l3E1t4/view , with a brief overview of the article here: https://swling.com/blog/2021/08/bob-colegrove-on-the-joys-and-challenges-of-tuning-analog-radios/ .
At some point (hopefully soon?) I need to plan the mechanical tuning arrangement for my homebrew shortwave superhet. I don't want to use a digital frequency counter and would prefer to stick to analog methods. The document linked above provides a nice overview of different methods and issues that occur when implementing an analog frequency dial.
My wife has a couple of these machines, and while staring at one last weekend, it occurred to me that they would probably be ideal for making lettering decal transfers, custom meter faces, frequency dials, etc., and possibly even cutting and etching complete panel overlays that could be placed over an unfinished surface:
Cricut Maker 3 | Cricut.com
I have a lot on my DIY plate as it is, so I don't think exploring this is something I will get to any time soon. She gave one Cricut to our daughter, who is sort of crafty, and uses the machine a lot, so maybe I can enlist her help in trying this idea(s) out.
Just an FYI.
Another source for analog capacitors, reduction drives, pointers, etc.
No experience with this supplier; put here as an FYI
I really like the idea, as described in the above document, of a Vernier dial (not a reduction drive, just an additional scale displayed next to the main dial) as a simple way to increase the reading accuracy by a factor of 10.
I did a quick mock-up of my own Vernier dial, with 100 divisions on the main dial.
When this is printed on paper with the main dial being about 10 cm in diameter, the Vernier dial is small, but still readable. Assuming the Vernier dial can be read, then this means we can gauge the position of the dial with an accuracy of 1/1000th of the range of motion. If this dial is attached to a bandspread capacitor, which covers a tuning range of say 1 MHz linearly, then we can (after calibrating the dial) estimate the tuned frequency to within 1 kHz, which I think is pretty good for an analog dial!
However, looking at the images above of the commercial Vernier dial, there seems to be an outer containing ring, on top of which is printed the Vernier scale, and inside of which the main dial rotates. Mechanically, this clearance must be very small, and must be very uniform over the 180 degree rotation of the dial, so that the tick marks on the main dial always line up flush with the auxiliary Vernier scale. This might be a job for 3D printing. A 10 cm dial could be printed, and a 10.1 cm diameter outer ring could be printed, leaving a clearance of 1 mm between the outer ring and the inner dial. The commercial Vernier dial pictured above seems to have even less than 1 mm of clearance between the inner dial and the outer ring, but that will be difficult to achieve with 3D printing.
Alternatively we could just forget about the outer containing ring, but then this means that placement of the outer Vernier scale, just on the outer perimeter of the main dial, would need to be judged by eye, which might not be accurate enough. Also, if we do not use an outer containing ring, then we need to be careful that the vernier scale and the face plate of the main dial are mounted so that they lie in the same plane, to avoid parallax errors when reading the vernier scale. So there is a bit of mechanical exactness needed here when assembling the parts -- but I think I can manage it even with my limited mechanical skills.
Also, accurately cutting out the circular paper dial label (to mount on the physical dial face) and accurately cutting out the curved auxiliary Vernier scale might be difficult if done by hand. Maybe a compass or a round template could help to cut the paper in a nearly-perfect circle.
I'm on board with this too. Looks really cool. The manual tuning seems to work well. I don't know if you found this person, but I order from him.
384pf Air Variable Capacitor with 8:1 planetary reduction drive https://www.mikeselectronicparts.com/product/384pf-air-variable-capacitor-with-81-planetary-reduction-drive/