L.S. Starrett Trammel Head 50-A

[Ayrhead]

1st Time I came across one of these sets. Comes in it’s own case. Internet says they are trammel heads. Not sure how it works but I thought it was pretty Kewl so I bought it…
Maybe some one else here has one as well.
Harry

 

[isb cornbinder]

The trammel heads mount onto a bar. The heads hold the points and the assembled unit is used to scribe arcs or circles. The screw in the heads is for fine adjustment.
I have had one since the late 1960s. I have a second set. I think the second set is a GENERAL.

 

[RTM]

Depending on the level of precision required, the bar can be metal or wood. As a woodworker, wood is good enough for me.

With those, you can rough set them with the top set screw, the fine tune your setting to the mark with the second screw on the one head. Really great for any circle over about 12” diameter.

 

[cvairwerks]

They can be used to check parallel or square or used as a story stick.

 

[crguy]

People refer to those as trammel points, not heads. Sure, there is a head that is part of the unit, but when you use them, they are trammel points.