What are the parts of a mitre saw protractor?

5th March 2020


	What are the parts of a mitre saw protractor?


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			All the parts below (e.g. rotatable arms, hanging holes, O-ring and pivot pin) make up the frame of the mitre saw protractor.

			Rotatable arms on a mitre saw protractor
			All mitre saw protractors have two arms which can be moved around the O-ring, to accommodate different angles. The arms are able to rotate 360 degrees, giving the tool more freedom to manoeuvre while measuring.

			Hanging holes Most mitre saw protractors have holes at the bottom of their arms which are used to hang the tool while it is not being used. The tool can be hung on a nail or by string so it is stored safely out of harm’s way.

			Mitre saw protractor O-ring
			The O-ring acts as a pivot, so the two arms can rotate around it.

			On the O-ring is a protractor scale, along with the arrows that point to the angle measured. When the arms of the protractor are moved, the arrows and scales rotate, providing a measurement.

			Pivot pin The pivot pin is a small metal link located on the back of the O-ring that holds the two arms of the mitre saw protractor together, allowing them to move around its axis.

			The pivot pin can be tightened or loosened to control the amount of tension in the hinge point. This can be done using an Allen/hex key inserted into the pin’s hexagonal head and turned. A hexagonal key is a tool used to manually drive bolts, screws, studs or pins that contain a hexagonal head.

			If there is enough tension in the pivot (O-ring), the arms will stay in position, holding the angle you measure. If there is hardly any tension in the hinge, there is a possibility that the arms will move after measuring an angle, providing you with an inaccurate measurement.

			To loosen the pivot pin and reduce tension, turn the hex key and hex head anti-clockwise. To tighten the pivot pin and increase tension, turn the hex key and hex head clockwise.

			Mitre saw protractor scale
			The two scales on the mitre saw protractor provide the user with angle measurements. The scale contains an inner arrow and outer scale (for single cuts) and an outer arrow and inner scale (for mitre cuts).

			A single cut is made for one workpiece to fit to an angle. A cross cut is an example of a single cut. A mitre cut is an angled cut, commonly at 45 degrees. The angles for these specific types are different because a mitre cut is used to form a mitre joint. Mitre joints are when two parts are joined to form a corner, so each mitre cut would be equal. A single cut is just one angled cut to one workpiece.

			Outer arrow and inner scale (mitre cut) The outer arrow points to the inner scale when measuring, to show the angle for a mitre cut.

			Inner arrow and outer scale (single cut) The inner arrow points to the outer scale to show the angle for a single cut.

			Two scale protractor on a mitre saw protractor
			A two scale protractor is found on the rear side of certain types of mitre saw protractors. When measuring, the protractor provides the actual angle and can also determine the angle of a roof when used with the roof pitch scale.

			The difference between this type of protractor and a standard mitre saw protractor is that if you measured a 90 degree angle, this protractor points to 90 degrees. A standard mitre saw protractor would show 45 degrees for a mitre cut (half of 90 degrees) and 0 degrees for a single cut. This is because 0 degrees on a mitre saw would be a 90 degree single cut.

			The protractor scales read from 0 to 180 degrees to 0, and 180 degrees to 0 to 180 degrees, this is so you are able to measure from left to right or right to left.

			Protractor arrow The arrow located above the protractor scale points to the measurement of the angle.