Wooden Plane Throat Geometry

I love old wooden hand planes. There’s something about tuning up a 150 year old woodie and putting it back into working order that is very satisfying to me. The thick laminated irons, the feel of wood on wood, and the simplicity of having no moving parts has a special appeal that I just don’t get when I use my iron planes.  I’m not saying that I dislike using my iron planes. I just like using the woodies more.

From the rear, a 2 ¼" x 8" x 47 ½ degree double iron smooth plane, a 2" x 7 ¾" x 45 degree double iron smooth plane, and a 6 ½" x 1 ¾" x 55 degree single iron smooth plane.
From the rear, a 2 ¼” x 8″ x 47 ½ degree double iron smooth plane, a 2″ x 7 ¾” x 45 degree double iron smooth plane, and a 6 ½” x 1 ¾” x 55 degree single iron smooth plane.

But have you ever wondered why most old wooden planes found in the wild have mouths that you could drive a Stanley #8 through? This condition is typically attributed to wearing down of the sole from use and routine re-flattening. And while it’s true that routine maintenance of a wooden plane will open up the mouth, there’s a little more to the story than just routine maintenance and wear.

Throat geometries of single iron and double iron wooden planes.
Throat geometries of single iron and double iron wooden planes.

The lower front of the throat on a wooden plane is called the wear. This area of the throat angles over the iron for about an inch before angling back in the opposite direction to form the upper throat where the shavings can be removed. The closer the angle of the wear is to the bed angle, the less the mouth will open as material is removed from the sole during flattening. In an ideal situation the wear angle and bed angle would be the same, but the wedge adds about 10 degrees so obviously that’s not possible. But there’s more to consider.

Observe the two drawings above, representing the throat geometry of a single iron and double iron plane. Notice how it’s fairly straight forward to create a nice tight mouth on the single iron plane. The wear in a single iron plane typically angles back over the bed at an angle of about 15 degrees greater than the bed angle. This provides for about 10 degrees for the wedge and another 5 degrees to provide for a bit more clearance for the shaving to be ejected. So in the drawing on the left above, the iron (red outline) is bedded at 50 degrees and the wear is cut at about 65 degrees.  In this drawing, notice how the front of the mouth is easily made right up against the cutting edge of the iron.

Now look at the drawing of the double iron plane to the right. Notice how the presence of the chipbreaker impacts the angle of the wear.  In this drawing, in order to create the same tight mouth that the single iron plane has, it was necessary to increase the wear angle to almost vertical. With a wear angle any less than the illustrated 80 degrees (a full 30 degrees more than the bed angle), the chip breaker would prevent the iron from being able to be extended through the mouth because it would contact the wear.

This is kind of interesting, because when we look at most double iron wooden planes, the wear angle is typically around 70-75 degrees. But based upon the drawing above, we’ve already established that if the wear angle is any less than 80 degrees, then the chip breaker would contact the wear and wouldn’t allow the iron to extend through the mouth (and if, by chance, it did, the shaving would get trapped between the wear and chip breaker). That is, unless the mouth was opened slightly.

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By opening the mouth up slightly, the wear angle can be kept lower.

As shown in the drawing above, 19th century makers of planes with double irons made a compromise. Most didn’t want to use such a steep angle on the wear because routine maintenance would result in a mouth that opened up very rapidly. So to slow the opening of the mouth, they chose to keep a slightly lower (70-75 degree) wear angle, albeit not quite as low as those found on single iron planes. However, in order to let the double iron through, and permit the shavings to pass over the chipbreaker, they chose to make planes with mouths that weren’t quite as tight as those on a single iron plane. Seems kind of like robbing Peter to pay Paul, doesn’t it? You open the mouth a bit right from the beginning in order to keep it from opening as fast later on.

Some would criticize double iron planes because of this.  However, proper use of the double iron more or less eliminated the need for the tight mouth that was so necessary in single iron planes. With the edge of the chipbreaker set very close to the edge of the cutting iron, the chip was broken before it had a chance to tear out, so the mouth could be slightly wider without any loss in performance. Unfortunately, this allowed wooden planes to be manufactured by less skilled workers as the 19th century progressed (many American wooden planes were made by prison labor later in the 19th century).  This eventually led to the demise of the wooden plane as the quality of these tools declined to the point that they were completely replaced by the modern iron hand planes.

The typical mouth opening of a "new" double iron wooden plane.
The typical mouth opening of a “new” double iron wooden plane. This plane has the tightest mouth of all of my wooden bench planes.

The plane pictured above is my 8″ long smooth plane with 2 ¼” wide double iron bedded at 47 ½ degrees. This plane was virtually unused when I bought it several years ago, and has seen very little maintenance flattening since then. As you can see, even though very little of the wood on the sole has been removed since the plane was made, the mouth is still much wider than what most would consider acceptable for a smooth plane today. However, with the chipbreaker set properly, I haven’t had any problems smoothing any of the woods that I typically use. In fact, I’ve never had a problem with any of my other wooden bench planes either and they all have even wider mouths than the smooth plane pictured above.

To me, this suggests that mouth opening on a double iron plane is less important than most people make it out to be, for the majority of situations. Sure, for some of the really squirrely grained boards that we occasionally run into, a really tight mouth might provide some limited benefit. But for the typical work that most of us do, I just don’t think that mouth opening on a double iron plane is all that important. A sharp blade and a close set chipbreaker are much more important in a double iron plane than a tight mouth.

In the coming weeks I will be making two new smooth planes using some old irons I have.  One will be a double iron plane, using the 2″ wide double iron from the middle plane pictured above (I bought the plane just for the iron). The other will be a single iron plane made using an old 1 ¾” iron given to me by a friend (not the one in the plane pictured above).  I’ll do my best to document the builds here, so that you can get an idea of the process in case you want to give it a try for yourself. Who knows, maybe I’ll even film the process. Stay tuned.

The Naked Woodworker – A Must Have for the Beginner

Naked Woodworker
Recently, my friend Mike Siemsen and the folks over at Lost Art Press put out a DVD called “The Naked Woodworker“. The DVD is aimed at the new woodworker who has no tools and no idea where to start. I picked up a copy to watch and then donate to my woodworking club’s library. After watching it, let me just say, that if you are the new woodworker I just described, you need this DVD. It will be the best $20 and the most valuable 4½ hours you can spend before you start woodworking.

The first disc of the 2-DVD sets starts with Mike at the MWTCA meet, buying tools. He tells you what to look for and what to avoid when shopping for tools. But most importantly, he focuses only on what tools you will need to complete your first two projects, a sawbench and a workbench.

This section alone is the kick in the pants that so many new woodworkers need to stay focused. I’ve long suggested that when you’re new to the craft you should focus on a project and let your project dictate the tools you start with, not the other way around. But far too often, the focus of new woodworkers is to try and buy every tool they think they might someday need before they ever cut a single piece of wood. Mike’s no nonsense approach to tool shopping shows you how to focus only on the good user grade tools that you will need to get the two projects done, without spending a fortune in the process.

In the second half of the first disc, Mike talks about how to get your new tools ready to go to work. Regardless of whether you go the new tool or old tool route, you need to know how the tools function, and more importantly, how to maintain them and keep them working like they should. All tools get dull in time, so knowing how to keep them sharp is the most important skill any new woodworker can learn.

The primary focus on this part of the disc is on sharpening plane irons and saws, but Mike does briefly discuss the setup of the rest of the tools he bought as well. Then, using a simple and inexpensive sandpaper setup, Mike sharpens the blades for all of the planes he bought in the first part of the disc, and shows you how to adjust the tools and get them working properly with minimal fussing. There’s no uber tuning and shaving measuring going on here. These tools are set up to build stuff, not show off on internet forums.

After the planes are set up, Mike moves on to the saws. The difficulty of sharpening ones own saws is so over exaggerated it can be sickening. The fact of the matter is that it’s really not that hard. It’s no harder than learning to sharpen a chisel or plane iron. It takes some practice, and while your first sharpening is not likely to result in perfection, it will still result in a saw that cuts better than a dull one. Mike shows you how simple it is and discusses both rip and crosscut saws, again, focusing on getting the saws to an acceptable working level, not striving for perfection.

Disc 2 is all about getting to work with your new tools. Mike builds a sawbench and Nicholson inspired workbench in this disc. The saw bench is straight forward, simple and inexpensive. The design gives you plenty of sawing practice, requires no complex joinery, and results in a rock solid, sturdy sawbench. Oh, and he builds it using only a pair of 5 gallon buckets to work on, because that’s probably all you will have to work with.

Then Mike goes on to build a full sized workbench, again, only using the sawbenches to build it, because that’s all you will have. Mike’s modified Nicholson bench design is really simple to build and incorporates a bunch of really great, inexpensive workholding options. Maybe I like the design because the way he built it is so similar to how I built mine, but it’s simplicity is only outdone by its functionality. Mike has made this bench so easy to build, using no complex joinery, that I’m betting my 9 year old daughter could almost build it with very little help from me. This is the first workbench every new woodworker should build.

So to repeat what I wrote above, if you are a new woodworker, just getting started, buy this DVD before you do anything else. If you follow along with Mike’s teachings in this video, you could have a basic tool kit, a sturdy place to work, and be on your way to building furniture in no more than a week or two.

18th Century Style Jack Plane – The Details

Last night I finished up my 18th century style jack plane.  This plane actually got its start almost two years ago when a friend offered up some quarter sawn beech planks to those of us volunteering at the museum that particular Sunday.  The planks were nice.  Not perfect, but I thought they’d possibly make some nice planes.  They were almost 20/4 square and about 5′ or so long.  So I cut the plank into a few shorter sections that would be a good size for plane blanks and set them aside to dry for awhile.  They warped and checked quite badly as they dried (as beech is notorious for doing), but since they were cut significantly over sized and about 5″ square, there was enough extra material to saw away to get a good plane blank.

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The donor plane…a 19th century Sandusky Tool Co. jack plane.

The second push to make this plane came a couple of months ago.  I had mentioned to a friend at a CJWA meeting that I was thinking about making a new single iron smooth plane and trying to find a laminated 1-3/4″ single iron to make it with.  As we were talking he told me not to go buying anything just yet because he just happened to have a few extra irons that he’d be willing to give me the pick of at our next meeting.  As promised, he brought in about 4 orphaned laminated single irons for me to look through at the next meeting, and in addition to the one single iron that I chose, he also graciously gave me the Sandusky Tool Co. plane pictured above.

The plane has two main issues rendering it unusable.  It has a pretty significant crack in the right cheek & abutment (hidden by the wedge above), and the bottom of the wedge is broken off.  He wasn’t overly concerned about the plane and told me to do whatever I wanted with it (I think his words were “…burn it if you want, I don’t really care about it”).  When I took the plane home, I looked it over and determined that it could be repaired and made into a decent user with a bit of work.  However, when I looked at the iron, I decided otherwise.

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An absolutely gorgeous double iron.

The 1-3/4″ double iron that came with the plane was in need of a light cleaning, grinding and sharpening.  But after cleaning it up a bit, it was in practically new condition.  The iron showed very little sign of use and was more or less full length.  The chipbreaker was pristine, as was the chipbreaker screw, having narry a scratch and a perfectly unmangled slot.  But most importantly, the iron was laminated clear up to the chipbreaker slot.  This iron was just too perfect to be put back into a mediocre plane.  So instead, I decided to make a new one.

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My new 18th century style double iron jack plane.

Made of the quarter sawn beech noted above, the plane is 15″ long, about 2-5/16″ wide and about 2-5/8″ tall.  The grain is oriented so the bark side is on the sole and the heart side is on the top.  The blank is so perfectly quartered it almost appears riven except for the radial grain on the sides that slopes down from the toe to the heel.  The double iron is 1-3/4″ wide, ground with about an 8″ radius on its edge, and as noted above, it is of laminated construction.

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Offset 18th century style handle.

As described in my previous post, the grain of the handle is aligned vertically in the typical 18th century style.  It is tenoned about 1-1/2″ into the body and drawbored with two oak pegs.  Also, typical of 18th century planes, the handle is offset to the right side of the body rather than centered.  This configuration provides for better balance in use but also favors right handed use (it can be used by southpaws, just not as ergonomically).

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Wide racing stripes!

The corner chamfers are big and wide.  This is one of the features that was minimized or eliminated in 19th century planes to reduce the cost of manufacture.  However, the wide chamfers with their small carved termination really give the plane the “right” look, in my opinion.  They also make the plane much more comfortable to use than later planes lacking this detail.

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Strike button and “bowtie”.

The strike button is ebony, because I had it.  It’s oriented so that it’s end grain is on top to give it the most strength.  It is set into the body about 3/4″ to 1″ (I don’t really remember to be honest).  The chamfered corners on the strike button just prevent the corners from splitting off.  The final detail is a small carved ornamental detail on the front of the throat.  I’ve seen this referred to as a “bowtie” somewhere before, but I can’t remember where.  It’s a nice little detail that is on the jack plane that I’ve been using for years, and I really like the look it gives the plane, so I added it here.  It’s not a typical feature of English planes, but I think it’s a nice touch, so I will make it a feature of my planes.

Overall, I’m quite happy with how the plane turned out.  It’s not perfect, and I will tweak some of the features on planes that I make in the future.  But for now, it’s a vast improvement over what I have been using, and it’s another tool in my arsenal that I can say I made myself.

Labor Day, Um, Labor

I spent the day greatly appreciating the work that people like Larry Williams & Don McConnell, Matt Bickford, Caleb James, Phil Edwards, and a host of others do every day to make these wonderful tools available to us.  Anyone who thinks that today’s premium hand planes are over priced should try building one for themselves.  After the work I put in today, I think these guys are charging just enough to get by, and probably should be charging more.  This stuff ain’t easy folks.  But it is fun!

Traditional 18th Century Style Jack Plane in Progress
Traditional 18th Century Style Jack Plane in Progress

More on Roubo’s Winding Sticks

When the name Andre Roubo is mentioned, most people’s first thoughts are of a massive workbench.  However, when you delve into the myriad of plates that were published as part of Roubo’s series of volumes on the many different facets of woodcraft, you will immediately realize that these books are about so much more than a workbench.

Plate 14 from Roubo's Volume on Furniture Making
Plate 14 from Roubo’s Volume on Furniture Making

My first introduction to Roubo came a little over a decade or so ago, just a few years after I sold most of my power tools and machines.  At the time I was engrossed in Moxon and Nicholson, but I was looking for more than what those two books were providing.  Somehow, during an internet search of old books on woodworking, I came across a bunch of PDFs of plates from an old French woodworking book.  I couldn’t read French, so I couldn’t understand any of the text, but the engravings were so well done that I was able to infer a lot of information just from looking at the various plates.  It wasn’t until a year or so later that I found out that I had been studying plates from Roubo’s various volumes.

The plate above, Plate 14 from Roubo on Furniture Making, was one of the first ones I noticed, I think primarily because there were so many things that were familiar on it.  From the try square, to the marking gauges, to the winding sticks at the bottom of the page, this plate was really consistent with many of the things I had seen and learned from the historic English texts on the craft.  However, the engravings at the very top of the plate were quite interesting to me.  It was obvious from the engraving at the top right that he was referring to another type of winding sticks, but these were a bit different than the typical winding sticks I had always seen and used (he appears to picture these at the bottom left of the plate).  I tucked the odd winding stick engraving away for awhile and went on doing other things for the next several years.

I came back to this plate recently when I was writing an article for Popular Woodworking Magazine.  I was researching the different types of miter squares I had seen for the article, and Roubo’s Plate 14 had one that appeared to have several different angles, so I built a version for the article.  I was again reminded of those odd winding sticks, but I hadn’t the time to try them out at the time.  So again the image got tucked back into the memory banks to be recalled at a later date.

Recently, Don Williams wrote a short blog about his own version of Roubo’s odd winding sticks.  Of course Don is the driving force behind the English translations of several of Roubo’s works, currently available, and soon to be published by the folks over at Lost Art Press.  While the volume on marquetry is currently available, the volume on furniture making is still in the works, so don’t go trying to find the above plate in the volume on your book shelf.  Don’s recent post reminded me of these unusual winding sticks, so since I had been making a new pair of traditional English style winding sticks anyway, I thought I’d finally make a pair of Roubo’s as well, and try them out for myself.

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Winding Sticks with Legs?

The first thing you notice about these winding sticks is that they aren’t just a pair of sticks.  Instead, each has a pair of “legs” that lift the stick off the surface of the board.  At first this seems to not make any sense.  How on earth can the sticks be used to assess a board’s flatness if they don’t even touch the board.  That’s when I realized that their primary purpose is not to assess flatness at all (though they can be used to do so, as I’ll discuss in a minute).  They’re winding sticks, they’re primarily used to assess wind.

Traditional "English" Winding Sticks
Traditional “English” winding sticks work fine across a cupped face…

Traditional winding sticks, while sometimes ornate like my new pair, can be nothing more than a pair of straight sticks with parallel edges.  When placed on the face of a board, they allow one to assess a board’s state of flatness and wind.  In the photo above, the gap underneath the bottom of the sticks indicates that there is a slight cup across the face of this board.  In addition, there is a very slight twist in the board as well, indicated by the left ebony inlay sitting slightly higher above the top of the front stick than the right ebony inlay.

But they don't work that well on the crowned face.
but they don’t work that well on the crowned face.

Traditional winding sticks have a drawback though.  They aren’t so reliable when assessing the crowned face of the board.  Sure, they’ll tell you if the board is crowned, but they really can’t be reliably used to assess wind on the crowned face because they have to be balanced on the crowned face.  This allows the sticks to rock on their centers, which can throw off the reading and make you chase wind that may not even exist.  Sure, you could just assess the cupped face, but if the board has enough cup and twist, trying to plane the cupped face can be quite a circus act as the board rocks on its crowned face.  Wedges under the high edges can help, but only so much.  Sometimes, it’s just easier to flip the board over and work on the crowned face rather than chase the board around the bench.

Winding sticks with "legs" span the crown and allow accurate assessment of wind on the crowned face.
Winding sticks with “legs” span the crown and allow accurate assessment of wind on the crowned face.

This is where Roubo’s winding sticks shine.  Because these winding sticks have “legs”, they are able to span over the crown in the board, and provide a precise assessment of the state of wind of the board.  The legs ensure contact with the board only at the outside edges, where it is most important for assessing wind.  But wait, there’s more…..

The "legs" also make correction of wind a breeze.
The “legs” also make correction of wind a breeze.

Closer examination of the engraving in Plate 14 reveals another interesting use of Roubo’s winding sticks on stilts.  Because the “legs” span over any irregularities in the face of the board, they make correcting any wind in the board almost as easy as detecting it.  Looking closely at the engraving, you can see that the legs of the winding sticks are actually reading off the bottom of a rabbet planed along the edge of the board.  This was the light bulb moment for me.  Using a simple rabbet plane, the wind in the board can be corrected by planing a rabbet that tapers from shallower at the low corner to deeper at the high corner.  When the sticks align, the wind is gone.  The resulting tapered rabbets then act as pseudo marking gauge lines.  Plane the remainder of the face of the board until the rabbets just disappear, and the face is free of wind.  By checking that the floor of the rabbet is flat from one end of the board to the other end, you are also ensured that the face of the board is flat.

Reading the board's condition from within the rabbets.
Reading the board’s condition from within the rabbets.

In the photo above, the rabbets were planed a bit deeper than they needed to be for illustration purposes.  This board actually did not have that much wind, but I made the rabbets a bit deeper than they needed to be just to show how I think these winding sticks would be used.

Winding sticks in the rabbets.
Winding sticks in the rabbets.

Above you can see how the rabbet is planed along the edge while the center of the board is left untouched.  The rabbets then become depth gauges for planing the board flat and free of wind.  As an additional benefit, the rabbets allow you to traverse the board (plane across the grain) without fear of blowing out the grain on the far edge.  When you get close to being finished, you can also slide the legs out of the way and use the sticks alone as a straight edge.  There’s a lot to like about this method, and these winding sticks.

So after building and using these winding sticks, I’m even more anxious to read Don’s detailed essay on them in the upcoming Roubo on Furniture volume that will hopefully be released later this year.  My observations are really based only on the engravings and my own experimentation.  I have no text to back any of this up.  So I’m interested to see how my experimental archaeology compares with what Roubo (and Don) actually wrote about these winding sticks.  I’m curious to see if there are any other uses for them that I haven’t yet discovered.

On the down side, the legs do make assessing minor wind a bit more difficult than traditional winding sticks without the legs.  The tops of the legs break up the straight line of the sticks, so when there is only a minor bit of wind, I find it easier to see with the traditional sticks.  However, I can see the legged versions being more useful for stock that is a little less flat to start out.  And using the rabbet as a marking gauge for planing is, in my eyes, just pure genius.  It allows you to more or less plane the entire surface of the board flat without constantly stopping to check for wind during the process, because you are simply planing to a line.

Can’t wait to see what other gems Don and crew have uncovered when the new volume comes out!

Episode #53: Tuning a Rabbet Plane

Woodworkers love hand planes. But in a period shop, the bench planes that are so coveted and extolled today were actually among the minority when it came to the tool inventory. The joinery planes and molding planes vastly outnumbered the bench planes. Today, amateur woodworkers are once again beginning to realize the usefulness of the joinery and molding planes in the small home shop. So the next few episodes are going to be a series on tuning up and using the joinery and molding planes. To kick off the series, I’m starting with the simplest of all the joinery planes, the unfenced rabbet plane.


 

Molding Planes & Mahogany: Chocolate Soufflé

Molding planes.

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Over my years of acquiring and tuning old molding planes, I’ve come to the conclusion that they’re very similar to our children. Sometimes when tuning up an old molding plane, they’re very well behaved, doing exactly what you ask them to without a single struggle. Other times, they’re defiant, ornery, and make you want to pull out what’s left of your hair. So it was with these three. One was the good little child while the other two were the devil twins. Still, when they’re finally all cleaned up and on their best behavior, there’s nothing in life (or in woodworking) that can bring a parent more pleasure than their children (or their molding planes).

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