How to Make a Nipkow Disc
The Nipkow (pronounced Nip-kov) disc is the most popular mechanical scanner and is also the easiest to make. The NBTVA often has readymade 32-line discs for sale in different sizes for sale to club members, but if you would like to build one yourself or want to create one in a custom format, here is a good place to start.
There are many different ways to make a Nipkow disc, and the results obtained are largely determined by the amount of effort put into the process. Good quality discs require high precision, and the maximum acceptable aperture deviation is generally considered to be one quarter of a picture element. (I hesitate to use the term "pixel" here, because although the signal driving the monitor nowadays is usually stored in a digital format, this display device is not digital and does not have discrete pixels. Each dot along a line simply blends into the next with no definite boundary.) With that said, respectable results can be achieved with the method that I used prior to having access to a laser cutter, described below.
Step 1: Make/Obtain a Pattern
The first step is to obtain or generate a pattern. If you are making a Club disc or a Baird disc, then there are several different patterns already available to choose from. Here is a PDF pattern for a 32-line NBTV disc. This one is the same but has markers for sync holes on the outside of the disc. However, if you are in need of a custom disc, there are a few programs available to generate your own. Some of them can be found on this forum post, but are no longer under active development.
Viddisc5 is a simple program written by Sam Hunt that makes disc patterns with or without sync holes. When generated, the image is placed on the computers' clipboard. You simply paste it into the image processing software of your choice. One drawback of this software is that the images it creates are relatively small, less than 1000 pixels on a side, so it only works well on discs smaller than 8 inches or so. But it's great for making indexing wheels for mirror screws or small slotted discs for syncing.
Another is club member Gary Millard's program DXFNipkow. As the name suggests, it generates simple DXFs for CNC or laser cutters, but can also be printed. This software is considered experimental, so test your design out on paper first before having it professionally cut. It also has the ability to make interlaced and non-interlaced multiple spiral discs. One thing to note here is that the holes are not actually holes, but points that should be replaced with the aperture shape of your choice, and sized using the aperture step feature.
If you still own an older PowerPC Mac, Sergei Ludanov KD6CJI has written a very useful program called Disk Designer but unfortunately no newer version is available. It outputs PDF files that are plenty large enough for big discs. This program was used to make the templates on this site. It can also create multiple spiral (non-interlaced) patterns. I have never personally used this program to generate a pattern since I don't own a Mac, but I have seen/used the results. However I have noticed an issue with certain aspect ratios being rounded to the nearest half-integer.
built my monitor vertically (like a record player) using orange LEDs harvested from some solar lights. A couple of low-value potentiometers and a carefully chosen "wall-wart" power supply rounded out the setup. Unfortunately, I was unable to get any pictures from this system because I found out later that the stereo was broken and only passed through the higher frequencies of the video signal. Shortly after that, I began work on my First Televisor.