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One of the planes I rescued from a yard sale has grooves in its sole, running front to back across the surface that contacts the wood. I'm having trouble imagining what their purpose could be, especially since planes are often used at a skew (turned slightly from the direction they're being pushed).

So what have I got here, what's it designed for, and are there any special yips I should know when setting it up?

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    See Record Jointer Plane No. 08C (Corrugated) for example. – RedGrittyBrick May 29 '15 at 19:46
  • What is yip? My English is not that great but I looked it up and "sound a small dog makes" doesn't seem to fit your question – OmarL Jul 24 '19 at 10:18
  • Typographic error, intended to be "tip" – keshlam Jul 25 '19 at 11:43
  • It is a plane used for fly rod building. – Jay May 25 '20 at 6:35
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One supposed advantage of a grooved, or corrugated, sole on a plane is to prevent the plane from "sticking" to the surface of the wood, similar to the way two panes of glass (or any two smooth surfaces) will stick together if there's no air between them.

It was originally intended to reduce friction by reducing the contact surface without compromising the plane's ability to produce a flat surface, though as aaron pointed out, in reality that isn't the case. You just need to wax the sole to reduce friction.

You cat set it up the same as you would a non-corrugated plane. As LeeG noted, a practical benefit is that there's less material to remove if you need to flatten the sole.

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  • Hm. Thanks! I vaguely remembered having heard of these, but it's the first time I've seen one. – keshlam May 29 '15 at 19:25
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    It is also easier to flatten the sole of a corrugated plane - there is less material to remove. – LeeG May 29 '15 at 19:56
  • @leeg: That'll be particularly useful in this case -- it was cheap because it needs the rust cleaned off and related restoration. – keshlam May 29 '15 at 20:56
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    The features you note are only intended but may not be actual. For example, friction is proportional to load, not contact area (which falls out as a variable in the derivation of friction forces)...so that doesn't quite work out! I heard that the original reasoning for this is that the corrugations can be filled with wax that would be held as a reservoir and slowly really lease over time and use... If that works it'd reduce friction. IF It works. – aaron May 30 '15 at 5:00
  • I agree and am skeptical .... but I think the conclusion is that I should restore the beast and find out. – keshlam May 31 '15 at 19:46
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Terminology note: the base of a plane is referred to as the sole.

Grooved or corrugated soles were intended to reduce friction by reducing the surface area of the metal plane in contact with the workpiece. That's the theory at least. The fact that corrugated soles did not continue to be made probably indicates most strongly that they didn't offer any significant advantage.

In the modern era, more than one woodworking guru has commented that they cannot notice any difference in use, especially if the flat-soled plane is kept properly lubricated with wax or tallow. Chris Schwartz for example notes: "I have planes with both smooth soles and corrugated ones, and if there is a difference in effort required to wield them, I cannot discern it."
(Read full piece here for further details as there are other advantages.)

especially since planes are often used at a skew (turned slightly from the direction they're being pushed).

Keen observation. I have wondered the same thing myself, and have been told that it doesn't make any difference. On wood that is already fairly smooth I can buy this but on wood that is still quite textured I can't imagine it wouldn't make at least some difference as there are multiple arisses moving across the texture versus just the one on the leading edge of a regular plane.

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  • Thank for terminology correction. I almost remembered that but didn't take the time to look it up. My bad. – keshlam May 31 '15 at 19:47
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In addition to reducing friction, a corrugated sole is easier to flatten. You are removing significantly less material if the sole is not dead flat.

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  • True! (And for those who don't know, flattening a plane's sole is one of the steps that can be taken to improve its performance. High-end planes have well flattened soles as shipped; midrange and used generally benefit from a bit of cleaning up.) – keshlam Jun 1 '15 at 16:11
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In the UK we're taught that grooved planes were used on particularly resinous timbers.

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  • Can you expand on this? Where in the UK? i.e., in school, on the job, read it in a book? Who would find such a plane the most useful? It sounds like a rare enough design that I suspect there are some specific case it is most useful. – jdv Jul 22 '19 at 13:32
  • Relevant quote from early-20th c. Stanley catalogues if you'd like to edit it in to you Answer. "These planes are made exactly like those on the preceding page with the exception that the bottoms are ribbed or corrugated. Some workmen are of the opinion that corrugated bottom Planes slide easier on resinous woods." – Graphus Jul 22 '19 at 19:41
  • So even Stanley is tacitly admitting. "we offer this option because customers requested it, not because we're sure it's an improvement." Good enough. – keshlam Jul 25 '19 at 11:48

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