Clock key size chart to get the right key

July 21, 2019 9:31 am Published by Leave your thoughts

Clock key size chart to get the right key

The clock key gets lost the most out of any other clock part. It can be tricky to find the right key for your clock because there are many sizes and also some have two ends on them. The type of clock key that has two ends on it is called a double end key and this is the most difficult to find the right fit. The below chart tells us what size key to get for either the wind up portion of the clock and also works the same for the F / S regulator side of a double end key. You can tell if your clock has a F / S regulator portion by just looking at the 12 oclock on your dial, if there is a tiny arbor there to turn, this is the F / S. The F / S stands for Fast or Slow, or it could say A / R to stand for Advance or Retard. This of course is referring to the timing of the clock. So if the clock is running fast in time, you would need to turn more to the Slow or Retard direction to slow it down some.

To get the key you need, measure the shaft the key is to go on to, then use this chart to get the key size # you need. Please do not call asking what key your clock needs, as you will be told it would still have to be measured. Again, you are measuring the shaft that the key goes onto in MM and then using the below chart.

Shaft width / Key #
  • 1.75mm = 000 Key
  • 2.0mm = 00 Key
  • 2.25mm = 0 Key
  • 2.5mm = 1 Key
  • 2.75mm = 2 Key
Shaft width / Key #
  • 3.0mm = 3 Key
  • 3.25mm = 4 Key
  • 3.5mm = 5 Key
  • 3.75mm = 6 Key
Shaft width / Key #
  • 4.0mm = 7 Key
  • 4.25mm = 8 Key
  • 4.5mm = 9 Key
  • 4.75mm = 10 Key
  • 5.00mm = 11 Key
Shaft width / Key #
  • 5.25mm = 12 Key
  • 5.5mm = 13 Key
  • 5.75mm = 14 Key
  • 6.0mm = 15 Key

Almost all post 1960 mechanical clocks, made in Germany take a size #8 key or crank, unless the movement is round. The round ones take a number 4 usually. The American time strike antique units mostly take the size 7 key.

- - The content of this web page and web site was written and copyright by James Stoudenmire of Clockworks.com - It may not be used commercially without permission. - -

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