One of the most important features on a mat cutter, and one that is often overlooked by first time buyers, is a squaring arm. The unschooled buyer is often concerned about the wrong things. Will my mat cutter warp? Unlikely. Will I have to change blades all the time? Not if you use a slip sheet. Will I have enough space for this? It's only 40 1/2" long; that's shorter than most ironing boards.
But they rarely ask the all-important question: How will I get my full sized sheet of mat board cut to size?
Life without a Squaring Arm - arrgh!
If you don't have a squaring arm, the unwelcome answer is that you'll have to get out a ruler, straightedge and pencil and mark out the pattern for the size you want on the back of the full sized sheet; and then you'll have to lay a long straightedge on the pencil lines and carefully score the mat several times on each line. A laborious, time-consuming process fraught with difficulty.
If you have a proper 90-degree straight cutting head, the cutting part will be easier, but you'll still have to mark out the sheet carefully by hand, a process that is way too time consuming when you consider that you not only have to cut down mat board, you'll also have to cut down foam board and sometimes glass.
The process is made instantly easier with the addition of a squaring arm. Be advised, however, that a squaring "bar" is not the same thing as a squaring "arm". A squaring bar is merely an abutment that keeps your mat board square as you cut it. It doesn't provide you a way to measure. Some mat cutters now include a combination of a squaring bar and a measuring bar, which is a long stick with a scale on it. But the combination of the two still falls well short of the utility provided by a squaring arm.
A squaring arm is a long arm affixed at a right angle to your mat cutter's guide rail. It will have a scale that runs its length. It does two things. It keeps your matboard square as you cut, and it provides a precise, reliable means of measuring so you can cut down full sized sheets without having to mark out lines.
Love that Squaring Arm
The utility of a squaring arm is made apparent when you are tasked with reducing glass. With the addition of a glass cutting accessory the cutting part is easy. It's the measuring part that will have you scratching your head. How can you measure glass properly if you can't easily mark on its surface? The answer is a squaring arm. By moving the edge of the sheet along the squaring arm to the proper point on the scale, lowering the guide rail and cutting, your glass will be reduced to size without having to make marks.
One final word of caution about buying a mat cutter without a squaring arm. If you do so, and then discover later that a squaring arm will be necessary to speed your sizing, you cannot retrofit a squaring arm to a mat cutter that didn't come with one in the first place, which means you'll have to buy a whole new mat cutter just to get that feature.
The lowest priced mat cutters in the Logan line that include a squaring arm are the Simplex mat cutters. Every mat cutter above the Simplex in price also includes squaring arms. Many people over the years have taken my advice to buy one of these mat cutters, rather than one of the lower priced models, just to get the squaring arm. They have never regretted it.
A squaring arm is the key to a smooth, efficient mat cutting experience. It's not something you will want to overlook.