How to Sharpen a Paper Cutter Blade
Paper has remained stubbornly indispensable in most businesses even with the widespread use of computers and mobile devices, so tools to handle paper are also still important. One of these is the guillotine-style paper cutter with a single large blade that can cut through a surprising thickness of paper when it's sharp. As the blade grows dull through use, you'll find it that sharpening it occasionally keeps it working at its best.
The first thing you need to know is that your cutter may not need sharpening at all, but honing. The cutting edge of a blade is very thin – be it on your cutter, a knife or a pair of scissors – and in normal use that fine edge can bend slightly, blunting the edge and impairing its ability to cut. Honing a blade simply means restraightening that edge, and it's what chefs do when they whisk their knives across a steel. You can hone the blade by removing it and running the flat side a few times across a sharpening steel or a piece of flat, unfinished industrial steel, or simply by using it to cut a few thicknesses of aluminum foil. If your cutter is relatively new or lightly used, this is probably all you need to do.
To sharpen the blade you need to remove it from its mount. Typically this means removing a number of small hexagonal bolts from the blade using an Allen wrench. It's best to remove them from each end and work your way to the middle, so the middle bolt holds the blade in place until the end. The instruction manual for the cutter or its manufacturer's website should have detailed instructions. Remember that the blade is sharp and handle it carefully.
Your cutter's blade is much like a knife except for its length, and it can be sharpened the same way on a whetstone. The major difference is that a cutter blade is usually beveled on one side and flat on the other, so you'll have just one side to sharpen. Use a large enough stone that you can draw the entire blade across it on each stroke. A fine stone of 1,000-grit or better – the higher the number, the finer the grit – is best. The trick is that each blade is ground to a precise angle, which is hard to replicate when sharpening by hand. Knife enthusiasts use adjustable jigs to solve this problem, and the same products would work with your paper sharpener's blade. Stroke the blade across the stone repeatedly, until it's shiny and sharp to the touch, then hone the reverse side to remove any burr before replacing the blade.
Sharpening on a bench grinder is faster if you have one in your maintenance shop or production area. You'll need to use a fine stone and be very careful about your grinding angle because the high-speed wheel removes steel quickly and if you make a mistake it'll be time-consuming to correct. You might find it easier to use a sharpening attachment on a hand-held rotary tool, which gives you better control. In either case, you should wear eye protection when sharpening the blade. Using a grinder wears out the blade more quickly, so you'll have to balance the cost of blades against the time you save by not hand-sharpening on a stone.
A third alternative is to simply delegate the task to a professional. Most urban areas have numerous sharpening services, and even relatively small towns have at least a hardware store with expertise in knife and tool sharpening. Cutter blades are more similar to knives than tools, so given a choice, you should lean toward services that focus on knives.
If you use your cutter daily but not at a pace that justifies multiple units, it's prudent to keep a spare cutter blade on hand and rotate them regularly. When one blade becomes dull remove it for sharpening and put the replacement in use. Swap them again when the second blade becomes dull. That way, if you don't have time to immediately sharpen the blade – or if your sharpening service lets you down – you won't need to stop work for lack of a functioning blade.