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): discontinued Sachtler part

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: Height adjustable piano stand
  • Adjustable press arm: Adjustable press arm
  • 4
    The first picture is called a "Devil's contact lens":. ;) Commented Jan 4, 2017 at 2:08
  • Looks like something you could make with a router on a sled, a 45° bit, and a rotary indexing table. I mean, assuming you don't have a little CNC machine :)
    – Samuel
    Commented Jan 4, 2017 at 21:27

2 Answers 2


What we have here is a Hirth Joint.

A Hirth joint or Hirth coupling is a type of mechanical connection named after its developer Albert Hirth. It is used to connect two pieces of a shaft together and is characterized by tapered teeth that mesh together on the end faces of each half shaft.

  • I learn something new here every day. These might help (though I'm not sure about sizes): nord-lock.com/nord-lock/wedge-locking/washers/introduction Commented Jan 3, 2017 at 17:08
  • Didn't realize that the two halves of the washer weren't separable. Mea culpa. Commented Jan 3, 2017 at 20:41
  • 5
    Possibly useful for searching, from the WP article: "Hirth-like joints are often found on camera support equipment, where they are called rosettes." Commented Jan 4, 2017 at 0:51
  • I only ever saw not quite those but similar disks in Ikea furniture and there they were used to "dig" into wood to stay in place better.
    – Maurycy
    Commented Jan 5, 2017 at 11:24
  • 1
    @Maurycy: I believe those are generally referred to as 'threaded inserts', 'insert nuts' or 'tee nuts' depending on how they dig into the wood. Commented Aug 24, 2017 at 23:45

Expanding from my comment on isherwood's answer. From the Hirth Joint article:

Hirth-like joints are often found on camera support equipment, where they are called rosette [joint]s.

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