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Drum sander setup

Step-by-step instructions for fitting an abrasive wrap
After calculating the drum’s circumference, measure for the angle to properly wrap the drum (see photos below).

After calculating the drum’s circumference, measure for the angle to properly wrap the drum (see photos below).

The drum sander is another simple machine that can perform in a way that will save a lot of effort and easily dimension or flatten some rough stock. A drum sander is simply a metal cylinder (or cylinders) powered by an electric motor that is wrapped with a coated abrasive (usually cloth-backed). It has an adjustable-height table with a motorized feed belt that can be adjusted up or down to allow for different material thicknesses.

The width and diameter of the drums can vary from sander to sander, along with the number of contact rolls, the horsepower of the motor, and a few other elements.

Make a pattern for the next time.

Make a pattern for the next time.

New operators struggle with determining the proper angle that needs to be cut on the end of the abrasive roll to make it fit their drum.

Most abrasive drum “wraps” (sometimes improperly called belts) are held on by mechanical, spring-loaded cams that lock in each tapered end of the abrasive material. Some are held on using a hook-and-loop system. Each requires a specific angle cut on both ends. To get the angle, measure the circumference of the drum that you intend on wrapping with the coated abrasive, since the length of the angle is exactly equal to the circumference of the drum.


To understand the “length of the angle”, imagine that you have a strip of sandpaper laid out on the floor. It is 3” wide (one of the most common widths for an abrasive wrap on a drum sander), and for the purpose of this example, it is longer than it needs to be. Your machine has a 5” diameter drum with a circumference of 15-11/16”.

The drum’s circumference can be calculated two ways:

Take the diameter of the drum and multiply it by pi. For example, 5” x 3.141592 = 15.707.

Take a flexible tape measure (maybe a cloth one as used in sewing), hold the end on the drum, and measure around the circumference.


Regardless of how you get it, once you have the circumference, you’re almost done. All that is left is to take a tape measure and, measuring from the right side of the 3”-wide abrasive to the left side, adjust the angle of the tape until you have a measurement of 15-11/16”. Holding your tape measure in place, take a Sharpie and mark the angle along the side of your tape measure. This is the angle you need to properly wrap your drum. Take a utility knife and cut the angle.

At this point, I encourage you to take a piece of 1/4” plywood – lauan, or whatever you may have – and rip it to match the width of your abrasive. Now lay it under the abrasive, line the sides up, and trace that angle. Once you’ve cut the angle on the plywood, you have a pattern that will help you to quickly cut the angle time and time again.


The simplest way of determining the correct length is to consult the manual that came with your drum sander or contact the manufacturer. Regardless of how you locate it, when you have determined the correct length, write it in Sharpie on the pattern that you created earlier.

Now that you’ve determined the correct length, lay your abrasive roll on the floor, or a long work surface, measure from the tip of the angle you previously cut, down the right side, and make a mark at the length that you determined earlier. Then lay your pattern on the abrasive with the long point on the right-hand side of the abrasive at the mark you just made, trace, and cut the angle.

One final tip: I like to drill a hole in the square end of my pattern and hang it from a nail or screw near the drum sander. That way it will always be handy when I need it.

Nick DeMars is a woodworking specialist at Klingspor Abrasives. He can be reached at 

This article was originally published in the September 2022 issue.

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