Tag-Archive for ◊ choosing rasps series ◊

• Tuesday, March 20th, 2012

Here are the other rasps that have been useful in my work. There are, of course, many more specialty rasps available than discussed here. Hopefully, you will have the opportunity to use high quality rasps that are suited for your work.

For the enjoyable work of shaping table legs, the Auriou curved “ironing” rasps have been very helpful. Pictured are the larger #8 grain, 1-1/8″ wide, and the #10 grain, 3/4″ wide. (I do not see the #8 grain available now, but there is a #9.) This type of rasp has a shallow curve along its length, useful for the gradual concave curves found in legs and other work. These smooth-cutting tools give excellent feedback to the hand when fairing curves.

Half-round rasps can be used to fair these curves but there are some disadvantages. As the convex face of the rasp is angled to the length of the leg, the contact profile is asymmetrical and often becomes confusing to feel. Also, there is less contact length, somewhat like a short-soled plane, and this makes it harder to feel the lumps and bumps that must be removed to fair the curve. There is also more tendency to tear the wood fibers. Do not be tempted to hold the rasp almost parallel perpendicular to the length of the leg because the teeth will slice the wood like tiny knives, you will not be able to control the rasp well, and deep scratches will be created; not how a rasp should cut.

Now, let’s say you’re at the bandsaw and both your mind and the cut wander, hopefully on the safe side of the line, and you end up with a lump on your otherwise nice leg. Hack it down with this beast, the Surform shaver. Don’t expect a lot of control or a uniform surface, but it is cheap and works quickly.

Click the thumbnail below to enlarge.

Returning to refined tools, for detail work, the Auriou #14 grain modeler’s rasp can be a lifesaver. It is thin and can be exquisitely controlled. It leaves only a very shallow scratch pattern, but can be made to remove wood remarkably fast for its size and grain.

Similarly useful, though a bit less smooth-working, is the Grobet detail file. While not a true rasp, its double-cut file pattern makes it function similar to a rasp. It is also versatile – four faces, flat and convex, each in coarse and fine.

Click the thumbnail below to enlarge.

The larger round rasp is an inexpensive model from Lee ValleyThe round needle rasp, made by Corradi, is helpful for various detail work such as enlarging holes. The handle, also from Corradi, has a chuck which allows the rasp to be removed.

Click the thumbnail below to enlarge.

This wraps up the rasp series. I hope it has been helpful. A final thought: it is easy to underestimate the value of a quality rasp. They are not pretty tools, but they can make a big difference in your work.

• Monday, February 27th, 2012

In the two previous posts, note the orange-colored handles on the Nicholson, Corradi, and Iwasaki tools. These are labeled “Disston” but, as far as I can tell, are no longer manufactured. I last bought some at least several years ago, I’ve forgotten from where, and have about eight in use and a few spares. Disston called them “Stronghold” handles as seen in this ad from 1930. They came in five sizes, from #1, the smallest, through #4, and the long, thin #0 for use with taper files for saw sharpening. The #3 is good for a 10″ rasp or file.

There are three relief slits at the front of the handle which is surrounded by a steel spring ferrule. This construction grips the tang of the rasp well, prevents extension of the built-in slits, and makes the handle reusable because there is some flexibility to the bore. Best of all, these handles feel just right in my hand.

I wonder if one of the hand tool manufacturers such as Lie-Nielsen or Lee Valley would be interested in making these handles if patent issues could be cleared. By the way, I do not have the Disston handles on my Auriou rasps only because I am unable to remove the less comfortable original handles despite lots of pounding.

Rasps are used more effectively if one adopts the attitude that this truly is a tool to be used with sensitivity. The rear hand (on the handle) supplies power and direction while the forward hand aids control with a light hold. Push to cut, disengage with a slight lift, retract, and repeat. The rasp is angled to the direction of push (remember the teeth are in diagonal rows), but avoid a pronounced sideways motion which will make the teeth slice into the wood across their width, causing the tool to grab and create deep scratches in the wood.

Adjust your push and pressure to the grade of the selected rasp which is based on the stage of the shaping process. Flip freely from the flat side of the rasp to the convex side depending on the contour of the work. As you get closer to finishing, lighten your touch. Use the weight and stiffness of the tool to sense lump and bump irregularities as you fair the curves of the wood. As with all woodworking, good adjustable lighting helps a lot.

For purchasing 10″ half-round rasps for fine furniture making, the subject of these posts, here are some suggestions. You can try out tools prior to making your choices at shows, some stores, Lie-Nielsen Hand Tool Events, woodworking schools, or your friends’ shops.

  • Low budget: Shinto + one medium lower cost hand-cut or maybe a Nicholson
  • Middle ground: Shinto + one hand-cut such as an Auriou #9 or #11
  • Better still: Shinto + #9 Auriou + #13 Auriou, and use a medium/coarse lower cost rasp that you may have acquired earlier for rougher or less critical work
Next: more rasps
• Saturday, February 25th, 2012

Moving up the rasp food chain to the hand-cut variety reveals the true capabilities of rasps. These have teeth that are cut (“stitched”) into a polished steel blank by a skilled craftsman using a metal pick and a hammer. The teeth are cut in diagonal rows but the handmade process introduces an important bit of randomness in their placement which creates a tool with control and smoothness in use that is unmatched by machine-made rasps.

It is the feel on the wood and the feedback through the woodworker’s hand which makes these rasps so effective. The teeth cover the surface across the entire width, typically at least 1-1/4″ in a 10″ long model, helping to give a direct sense of where the tool is cutting. Because these tools are used for shaping, their superb sensitivity in the hand is paramount.

There is an increasing number of hand-cut rasps available but I will comment only the Auriou brand which I have used for several years. I use the 10″ #9 and #13, a combination which has been marvelously effective in shaping legs, one of my favorite things to do in the shop. They’re not cheap but have proven well worth the investment. Here are two sources: Lie-Nielsen and TFWW. Here is a close-up of the #9 and #13 teeth. Click to enlarge.

It pays to store rasps so they don’t bang against each other, and keep them clean with the method described here.

Here is a list, not necessarily exhaustive, of other hand cut rasps available. Also, here is a suggestion to Popular Woodworking, Fine Woodworking, and the other woodworking magazines: this would be a good topic review, especially since there is a considerable range of prices. In the meantime, reader comments are welcome.

Another tool that is not a conventional rasp but deserves mention in this discussion is the Iwasaki float (“rasp” in at least one catalog) which is effective for shaping. I like my 8″ x 3/4″ “fine” flat Iwasaki. It is essentially a very sharp float with discontinuous arc-shaped teeth, which make the cutting action smoother. When I’ve tried conventional float files on repeated occasions, I found them grabby, though admittedly this was probably due to my inexperience. Nonetheless, the Iwasaki felt good right away.

The Iwasaki is useful in the late stages of shaping to clean up surfaces, and it can even be used to take a bit off tenon cheeks with good control. They are also available in convex profiles. Here is a close up, click to enlarge.

Rasps seem to be looked down upon by some fine woodworkers as less sophisticated than edge tools for shaping. I disagree. I own and use spokeshaves, specialty planes, and gouges. All of these tools have a role in shaping. An excellent quality rasp allows a skilled craftsman to execute just as much control and sensitivity as any of the edge tools. They work!

Next: Disston handles, some technique, and suggested rasp sets to own.

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• Sunday, February 19th, 2012

Woodworkers are fortunate now to have many more choices in quality rasps than were available in the recent past. Here we will look primarily at the workhorse configuration found in most furniture makers’ shops, a 10-inch half-round (one flat face and convex across the width of the other) 7/8 to 1-1/4 inches wide.

First, let’s dispense with rasps which have their teeth cut by machine in neat rows, sometimes referred to as “wood rasps.” These low-cost hackers should be considered DIY tools unsuited for fine furniture making. The problem is the uniform rows cause too many teeth to catch the wood at the same time and depth, sink in, then come away with an abrupt tearing of the wood. Though this effect can be reduced by angling the rasp and adjusting the stroke, a better solution is to get a better rasp. As an analogy, imagine if raindrops hit you in tight groups of eight, instead of the random scattering of real rain. You get just as wet in both cases, but you would feel intermittent strong impacts in the first case (like uniform rows of teeth), instead of the steady smooth shower of real rain (like quality rasps with irregularly distributed teeth).

Probably the most bang for the buck (about 25 of ’em) of any shaping tool in the shop is an unusually constructed rasp, the Shinto “saw rasp.” These are made from hard hacksaw-like blades melded together in a pattern that presents irregular phalanxes of teeth to the wood. Both sides are flat, one coarse, one medium. I prefer the model without the auxiliary handle which handles much like a regular rasp. It is a fairly rough tool, but the cutting action is surprisingly controlled. There is very little clogging and the tool lasts seemingly forever. I use mine early in the shaping process, and it is a great tool for mockups. This is also a way to save your best rasps from unnecessary wear. I wish the company made a version with the medium cut convex along the length and/or width.

Now let’s look at two brands of machine-made rasps with irregular tooth distribution, a key factor in producing a controlled smooth cut.

The Nicholson #49, and the slightly finer #50 have been old standbys, and, for a long time, about the only alternative to row-toothed rasps. The current crop, according to what I read, is made in Brazil and the quality has gone down. I still use my old USA-made pair and though they are good rasps, they are not what I reach for first. They are barely 7/8″ wide and teeth do not cover the full width. I prefer a rasp 1 1/4″ wide for general shaping. Though surpassed by better options, especially hand-cut rasps, these still might meet your needs at a low price. I don’t fine much difference in action between the #49 and the #50, so you could do well with just one of them. A close-up of the teeth my #49 and #50 (not the current production), click to enlarge:

Corradi “Gold” rasps are lesser known but excellent tools which are different in character from any others I know of. The machine cut teeth are densely packed in a wavy pattern which effectively presents the teeth randomly to the wood, giving a very controlled steady cut that feels almost like coarse sandpaper on a stick. My 10″ x 1-1/4″ #8 and finer #10 leave the least scratches of any rasps I’ve ever used. Not particularly aggressive, they come into play in the later stages of shaping. They tend to clog relatively quickly but clear easily. The Corradis have earned a solid role in my work but, as a matter of personal preference, do not have the special feel and feedback of the top-quality handcut rasps. A close-up of the teeth of the Corradi #8 and #10, click to enlarge:

Coming up: handcut rasps, handles, some technique, and more.