Pipe Radius Markers

Radius marker heads are machined from durable aluminium and include a stationary head with a hardened centre point and a movable head with a hardened steel scribe. They accept soapstone, pencil or steel scribe and work with any circle from 1½" diameter upwards, depending on the length of pipe used as the trammel.

Pipe Radius Marker FAQs

What is a pipe radius marker used for?

A radius marker (or trammel head set) is used to scribe accurate circles, arcs and radii onto pipe, plate or structural steel. In pipe work, they are commonly used to mark out branch saddles, circular cut-outs and curved template lines where precision is essential. The heads mount on a length of ½" pipe to create a trammel of any desired radius.

How do Curv-O-Mark radius marker heads work?

The two heads clamp onto a standard ½" pipe at the required distance apart. One head holds a hardened centre point that anchors the trammel, while the moveable head carries a steel scribe or soapstone that marks the arc or circle as the tool is rotated around the centre point. The spring-loaded clamp mechanism keeps both heads firmly locked at the set radius during use.

What pipe and plate sizes can radius markers be used on?

Curv-O-Mark radius markers can mark circles from 1½" diameter upward, the maximum radius is limited only by the length of ½" pipe you use as the trammel bar. This makes them practical for both small-bore layout work and large-diameter applications on plate or structural steel where consistency and accuracy are critical.