I'm building a piece of furniture with an adjustable part and would like to use a toothed disk similar in concept to the examples show below. Before having it custom made, I am searching for a manufacturer, maybe buy something off-the-shelf. Problem is, I'm not even sure what this would be called… Can you tell me a proper/generic name for this?
A web search for "toothed disk" turns up a lot of cogs and wheels, however only one of those hits is for something similar to what I am looking for (and is discontinued): 
The concept is that 2 of these disks are fastened to the opposing pieces. Pulling the 2 pieces together with e.g. a bolt causes the teeth to engage, and so the 2 pieces are fastened to each other at a fixed angle, which can be adjusted to suit needs.
Other real life examples that I have seen this used in:
- Height adjustable piano stand:
- Adjustable press arm:
Best Answer
What we have here is a Hirth Joint.