Posted by
Easy WoodCraft on
May 10, 2017
Even though rasps closely resemble files, they're very different beasts. Instead of single rows of teeth cut into the metal surface at an angle, rasps have tiny individual teeth in parallel rows. And unlike the smooth, almost planing action of a file, a rasp is designed to virtually tear out chucks of wood. This makes them very aggressive, and a rasp in the hands of a seasoned user can remove a lot of material in no time flat. That's why rasps are reserved solely for roughing-out work that will eventually be smoothed with files, scrapers, or sandpaper.
Most rasps are around 8" to 12" long and come in coarse, bastard, second-cut, and smooth grades. You may also see them described as either a wood rasp, a cabinet rasp, or a patternmaker's rasp. Wood rasps are the most aggressive of these and usually come with a bastard cut in either flat or half-round profiles. Cabinet rasps are typically second-cut or smooth and also come in half-round and flat (halfround being the more common). Patternmaker's rasps are also available in secondcut and smooth, and they generally have smaller teeth that tend to leave a smoother finish than the cabinet rasp.
One of my favorite rasps is a 4-in-hand rasp (originally called a shoe rasp). This handy tool combines four tools in one, as you'd guess from the name. Its doubled-ended with a half-round shape. One end is a rasp, the other a file—youd think they'd call it a 4-in-hand rasp/file. Effectively, you have a half-round file, a flat file, a half-round rasp, and a flat rasp. What I like best about this tool is that both edges are "safe," or smooth. This makes the 4-in-hand rasp particularly useful when rounding-over tenons to fit into rounded-end mortises, like those cut by a router.
I also like how the shorter body fits nicely
into my hand—and my shop apron pocket, too. My only use for this tool is light work, like fitting a joint or rounding-over tenons. If I have a lot of wood to remove or I'm working on a long or large surface, I'll pull out the appropriate standard-length file or rasp, since the short body of the 4-in-hand is inadequate for this type of work.
FILECARDS
Files and rasps require a lot of maintenance—a lot more than some woodworkers give them. No wonder the tool skips over the surface instead of cutting properly. Most often it just needs to be cleaned, and you should do this after every half-dozen strokes or so. I know a lot of folks who've never cleaned their files. The problem is, the tiny teeth of a file quickly fill with waste. If you don't remove it, the file can't work properly. Here's where a filecard comes into play. Filecards typically have two faces: a nylon brush on one face and a wire brush on the other. Start with the nylon brush, and if this doesn't clean the file, flip it over and use the wire side. Stubborn bits can be removed with the steel pick that's commonly built into most filecards.
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