Are there wood planes for curves?

Yes. They are called compass planes (or circular plane, ship’s plane or radius plane). These tools have a rich history, used by ship builders, carriage builders and furniture makers throughout history. They are unrivaled by other planes and sanding blocks for smooth, sweeping curves.

The compass plane is used mostly as a shaping plane, similarly to the way a jack plane is used for flat surfaces. When the correct radius is achieved it stops cutting, thus preventing over cuts and loss of contour. It can be adjusted to any curve with a flexible metal sole, either convex or concave. The adjustments are exactly what you want where you want them. There is no need to rely on step adjustments that lock in at increments. Its flexibility is the characteristic that makes the tool a great one to have in your tool box. Literally, any curve can be shaped with this one tool.

Some drawbacks are chatter, tearing and clogging. Think of the tool as a shaping tool, rather than a finishing tool. By doing this, it will help cut down some frustration with its negative characteristics. Any tear outs or dings can be smoothed with a spoke shave or a card scraper. But if set properly and handled well, there should be no need to do a lot smoothing or scraping.

Following some simple pointers for using the compass plane will alleviate some of the drawbacks. Hence, it will make working with the tool a pleasant experience rather than a headache.

Hints for using a compass plane:

  • Basic adjustments are very similar to setting up your standard bench plane, depth of cut, lateral adjustment, checking the mouth (gently checking that the blade is in position with your finger, key word “gently”). Don’t just eyeball it.
  • When shaping a curve, start with a tighter radius on the sole, make light cuts and slowly increase the curve of the sole to match the final arch.
  • For final cuts, closest to your desired curve, adjust the sole with the adjustment handle on the front of the unit. Match the desired curve and then for inner curves loosen it a little bit, approximately 1/8 inch. For outer curves, match the curve then tighten it a bit, about 1/8th inch.
  • Work downhill grain (with the grain), which means you have to turn a lot.
  • Be sure to cut out a clear lay out line.
  • Remove some of the lumps and bumps of the chiseled or sawn surface with a rasp (not a sanding block) to create a smoother surface for planing.
  • Be patient with the short shavings, they will be short in the beginning of shaping.
  • Stability is not as great, as with a flat plane. You do not get the benefit of stability, that you do with a flat plane. With your dominant hand, be sure to hold the back of the plane as close to the heel as possible. With your other hand, hold the front end firmly, with your thumb resting on the top of the heel plate.

How to use a compass plane

Setting up the blade is exactly the same as setting a standard bench plane: depth of cut, lateral adjustment, tension, sharpening the blade, checking the mouth, nothing new here.

Some have number markings as guides, but the best way to know what curve you want on the base plate is to match it to the actual final curve.

Following the hints above, adjust the curve of the plane to match your curve, giving a little more of a curve for the first cuts of a concave, and giving a little less for the first cuts of a convex curve.

Set the curve on your heel plate by turning the large adjustment handle in front of the blade mouth.

Instead of trying to shape directly from flat edge to curved edge, roughly cut away excess. Using a hand saw, cut down to approximately 1/16th inch above the line you have drawn, cutting in intervals. Then, chisel out the pieces. Once you are done, you have the basics of your curve, with enough of a margin to allow for shaping with the compass plane.

Then adjust your compass plane, following the above hints. When you are carving a concave curve, the plan curve should be a little flatter, because as you press down it will actually bend a little more.

Start on one end, push down towards center, but don’t go all the way up to the other side. When you no longer produce shavings, then you have achieved the curve. Turn to the other side and do the same.

Now, you want to shape down to your drawn line. Start back further and make a full sweeping cut. You should get a nice long shaving. Start back further again. Continue starting a little further back, until you meet your drawn line.

What is the difference between the compass plane and the Japanese Sori Ganna

The most outstanding difference is that the Sori Ganna (or Kanna) is made from a wood block and not adjustable.

It is an incredibly simple design, basically, a wood block with a wide groove for a blade and a mouth for the cutting edge. The cutting blade is a bit chunkier than the blade in the standard bench or compass plane. It is set in a mortise and tapped to adjust.

As is true of all Japanese planes, the cut is made towards you instead of away from you. Some thoughts about why, are related to the Japanese physique, which tends to be a bit smaller than others. So, pulling a blade will use the larger back muscles, rather than pushing which requires the smaller shoulder muscles. So, it might be a great idea for people who are not as strong to consider using Japanese planes for their woodworking projects.

Conclusion

There are planes for many purposes: scrub, jack, jointer, smoothing, block, finger, rabbet planes, moulding, combination and compass.  Adding the compass plane, for shaping curves will provide the hand tool woodworker with more options for beautiful projects.

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