How to measure for crown mouldings with a combination mitre saw protractor?

5th March 2020


	How to measure for crown mouldings with a combination mitre saw protractor


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			Mitre saw protractors are commonly used to measure and determine angles, so that mitre and single cuts can be produced. However, some designs feature a conversion table which allows you to measure for compound cuts in a few simple steps. On a conversion table, values for the spring and corner angles are converted into mitre and bevel angles so that you are able to produce compound cuts. Read on to find out how to apply the conversion table to produce compound cuts when installing crown mouldings.


			Step 1 – Find spring angle First you need to know the spring angle of the crown moulding. This is the angle between the wall and the ceiling, where the crown moulding sits. The angle is measured from the back of the moulding to the wall.

			The typical angle for a crown moulding is either 45 or 38, simply because they are sold with these specific spring angles. Measure the spring angle by placing the bottom of the crown moulding on a flat surface.

			If you are using a downloaded conversion table and a mitre saw protractor to measure the spring angle, you will need to use an angle measurer such as a digital angle rule. Only combination protractors contain a protractor that can measure a spring angle. Note that this is only an example. You can use any type of angle measurer that can adjust to measure angles up to 45 degrees.

			Step 2 – Check spring angle Once you have measured the crown moulding, turn the tool over and read the display to determine the spring angle.

			Check the display or scale of the angle measurer if you are using the downloaded conversion table.

			Step 3 – Measure corner angle Place the arms of the protractor against the corner angle where you are going to be installing the crown moulding.


			Use the spring angle and the mitre cut angle and transfer them over to the conversion table.

			Step 4 – Use conversion table Using the conversion table on the combination protractor will help you to find the correct mitre and bevel angle so you can produce a compound cut to install crown mouldings. Locate the column with the appropriate spring angle.

			Then make your way down the left side of the table to find the mitre cut setting

			For the mitre angle, keep in the relevant degree crown section, then look across the relevant degree mitre cut row until you see the first column labelled ‘mitre angle’. This will give you the correct mitre angle for the crown moulding.

			Now repeat the above step, but this time reading the second column underneath the relevant degree crown labelled ‘bevel angle’. For instance, the bevel angle for a 38 degree crown and a 46 degree mitre cut is 34.5 degrees.

			Step 5 – Transfer angles to mitre saw Finally, using the mitre and bevel angles from the conversion table, adjust the settings on your mitre saw. You will then be ready to cut your crown mouldings.