The Confusing Grey Area of Type Study Transitions

Block Planes from the Author's Collection

Block Planes from the Author’s Collection

As I’ve written before, I periodically receive questions from readers.  I really enjoy this, and a few of these questions have led to good friendships along the way.  In a recent correspondence with one of my long distance tool friends, the following question was posed.  I thought it was a good one, and worth sharing…

I have a No 4 type 5 and the iron has the “J” trademark which was allegedly used 1874-1884.  I think it’s original to the plane and the “nut” hole is at the top of the iron. The lateral adj lever is the single piece and everything else adds up. According to the type study (if one goes by that) that particular plane was produced 1885-1888. Now, also according to the type study that plane should likely have an iron with TmP, which I have but the hole is at the bottom of the iron which wasn’t supposed to happen until type 6 planes 1888-1892.  …I know type studies are a modern phenomenon but obviously are used today to determine the approximate time the plane was manufactured and sometimes it has a real effect on the value. …  The type study seems to be a little off on this particular time line but am I putting too much value on the information anyway? I haven’t studied this long enough to understand how the studies determined typing but now I’m not sure that the specificity of subtle changes determining the difference in type is valid. I think my plane has the correct Tm on the iron but a type study would lead someone else to question it.   – Mark

Mark, you nailed it – specificity of subtle changes determining the difference in type is, in fact, NOT always valid.  It’s actually kind of interesting that our brains all seem to want to interpret type studies in a very organized, linear manner.  Strictly speaking, when the type study for Stanley bench planes was created, the transition points from one type to the next were logical from a feature standpoint, but somewhat arbitrary from a date standpoint.  Take your Type 5 to Type 6 transition, for example.  The type study dates the type 5 from 1885 to 1888, and the type 6 from 1888-1892.  While the transition of some features, like the re-design of the frog receiver, probably switched on a specific date, other changes were implemented over time.  And remember that despite what the type study leads us to believe, all the changes implemented (where we mark the transition from one “type” to the next) were not coordinated.

When Roger Smith created the type study, he made judgment calls for when to mark the date of change from one type to the next, which makes sense in the context of a type study.  However, in reality, the transition from one type to the next wasn’t so prescribed, and actually reflects an unspecified period of time in which there would have been a mix of features.  It wasn’t a single month or year in most cases, but likely a period of one to several years.  In a couple of cases, this transition period was so pronounced that the type study includes references to “hybrid” types, as is well documented between types 8 to 9.

The guys at Stanley were brilliant when it came to product differentiation and marketing.  They knew how to keep their line of tools fresh and relevant, and implemented subtle changes to help remain current and sustain demand.  Some of their changes were likely implemented for that reason alone.  The trademark stamp on iron, for example, served no functional purpose.  As such, I imagine that changes from one mark to the next took place independently of most other design changes, and therefore has the least correlation to the type studies.

A lot of people point out that the change from one plane “type” to the next should be interpreted very differently from how we understand the change from one model year car to the next.  This is true.  Comparatively, Stanley’s planes were more like today’s computers, where change is an ongoing evolution rather than a series of annual steps.  Imagine 100 years from now someone trying to create a type study for Microsoft/Intel based personal computers.  I can envision some poor soul trying to understand why his vintage “Type 4” Dell PC has a Pentium IV processor, when the “type study” clearly states it should have a Pentium III.

So, don’t fret, Mark.  What you have is a late type 5 or very early type 6.  The mix of features simply indicates the plane was probably made during that period of transition, and if anything, actually helps narrow the date range.  While you can’t prove it, you’d be quite justified to estimate the date of manufacture to sometime between, say, 1887 and 1889.  And you’d probably be pretty darn close.

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Sharpening Angles for Bench & Block Planes

Sharpening Basics

Since sharpening is such an expansive topic in and of itself, I will leave the specific how-to details for other posts.  What you need to know in the context of fine tuning, however, is that any plane, new or old, requires initial sharpening and honing.

At a minimum, new plane irons need to have their un-beveled side flattened and polished to at least 4000 grit and preferably 8000 grit.  You don’t need to fuss with the entire surface; just the first 1/8” to 1/4” along the cutting edge is all that matters.  You also need to put a final honing on the bevel edge itself.  It may look sharp, but it needs to be honed, again, ideally to 8000 grit.  The goal is to get your cutting edge to as close as possible to a zero degree radius.

Sharpening is too often the deal breaker that dissuades woodworkers from trying hand tools.  This in unfortunate, for it requires little monetary investment to get started, is not particularly difficult to learn, and can be accomplished rather quickly with surprisingly good results.  For detailed information on the how-to of sharpening, I recommend investing in one (or both) of the outstanding books on the subject by Ron Hock or Leonard Lee.   Chris Schwarz has also written a number of fantastic articles on planes and sharpening plane irons.

Getting Down to Business

If all you want to know is what bevel angle to sharpen on your plane iron, make it 25º and call it a day.  But if you want to better understand the reasoning behind the geometry and some of the variations possible, read on.  In order to master your tools, it’s helpful to understand the principles behind the geometry at play.  So, first a few concepts and then we’ll tie them all together.

Frog Assembly

The frog is screwed to the body of bench planes

First things First – Before you can determine the optimal angle at which your plan iron should be sharpened, you first need to know the angle at which it sits in the plane.  Plane irons are held in place against the frog via a clamping device called the lever cap.  The frog is attached to the base, or sole, of the plane and provides an immovable seat for the iron.   The angle of the frog face is not adjustable, so it must be considered a constant.  On standard bench planes, the angle is usually 45º while on low angle planes it is typically a very shallow 12º.  This angle is traditionally referred to as the ‘pitch’ of the plane.

Pitch / Angle of Attack – Pitch, or what Ron Hock refers to as the Angle of Attack, is the angle at which the cutting edge engages the wood. [1]   As stated above, most bench planes have  a bed angle of 45 degrees.  This is referred to as ‘common pitch,’  and has traditionally been considered the optimal pitch for bench planes.  A slightly higher 50º pitch is called ‘York Pitch.’  This higher angle pitch is used in some bench planes for working harder woods and woods with difficult grains.  ‘Middle Pitch’ of 55º and ‘Half Pitch’  (also known as ‘Cabinet Pitch’) of 60º are frequently found in molding planes for soft and hardwood respectively. Angles of less than 45º are referred to as ‘Low Angle’ or ‘Extra Pitch,’ and are used in planes for softwood and for cutting end grain. [2]

Here’s a summary table of the different pitches and their intended use.

Pitch (Angle of Attack) Name Use
60º Half Pitch / Cabinet Pitch Molding planes for hardwood
55º Middle Pitch Molding planes for softwood
50º York Pitch Harder woods with difficult grain
45º Common Pitch Optimal Pitch for most planes
<45º Low Angle Softwood and End Grain

Bevel Up vs. Bevel Down – All planes fall into one of two categories – Bevel Down and Bevel Up.  Bevel down planes have irons that are situated with the bevel angle facing down, while the irons on bevel up planes are positioned with the bevel angle facing up.  Most bench planes are bevel down while most block planes are bevel up.  Specialty planes can go either way, depending on their intended purpose.  There are some advantages to the bevel up configuration, but we’ll cover that later.

Regardless of whether the plane is bevel up or bevel down, the angle of the frog face (upon which the iron sits) is an important determining factor in determining the desired bevel angle.  As stated above, the vast majority of bench planes have frogs with a 45º bed, meaning the cutting iron sits at a 45 degree angle from the work surface.  Since these bench planes are bevel down, changing the bevel angle doesn’t change the pitch, or angle of attack – that’s essentially fixed at 45 degrees.  Changing the bevel angle does, however, change the relief angle, or clearance behind the iron.

SB605 Type 6

Bevel Down Bench Plane

Bevel Down Planes – Since the irons on most bench planes are positioned bevel down, this is the most common configuration faced when sharpening.   Because the un-beveled side of the iron is positioned up (i.e., bevel side down), the angle of attack is the same regardless of the angle at which the bevel is sharpened.  That doesn’t mean the bevel angle is completely unimportant; durability, for example, is still a consideration.  The bevel angle is, however, less critical than it is on bevel up planes.  That said, there are still a few tricks you can employ to fine tune your angle of cut, but more on that later.

The standard primary bevel angle for bevel down bench planes is 25 degrees.  This offers a good balance of shearing action and durability while providing an adequate relief angle (behind the cut).

SB65.5 Type3

Bevel Up Block Plane

Bevel Up Planes – Block planes have the iron positioned bevel up, but they’re not the only planes with this configuration.  Low angle bench planes, including the Stanley no. 62 and the Sargent no. 514 were bevel up, as are several models made today by Veritas.  There is an advantage with bevel up irons in that the angle of the bevel can be changed to affect a change in the angle of cut.  This provides a measure of flexibility that bevel down planes don’t have, at least not to the same extent.

While there is more to consider in edge geometry than just the angle of cut (i.e., durability), you could reasonably sharpen the bevel on the iron of a low angle block plane iron to 33 degrees.  Given its 12º bed angle, you would end up with an angle of cut of 45 degrees (12º+33º=45º), the same as on a standard angle plane.  By contrast, to accomplish a low angle of cut using a standard angle plane, you’d have to sharpen the bevel at a very shallow 17 degrees (20º+17º=37º).  Durability of such a thin cutting edge would be problematic with most woods.

See “Beyond the Standard” below for information on adding secondary bevels (micro-bevels) and back-bevels.

Common Sharpening Angles

The table below shows the three most common bench and block plane types and the proper angles at which to sharpen the irons.

Common Plane Types Frog Angle Angle to Sharpen Angle of Cut
Bench Plane – Standard Angle 45º 25º to 30º 45º
Block Plane – Standard Angle 20º 25º 45º
Block Plane – Low Angle 12º 25º 37º


Beyond the Standard

Secondary/Micro-Bevels – The terms secondary bevel and micro-bevel refer to the same thing.  Secondary bevels are a very shallow bevel along the cutting edge of the primary bevel.  These angles, usually 1º to 3º, serve primarily as an aid in honing.  It takes considerably less time and effort to final hone a small secondary bevel that it does the entire primary bevel.  They also make honing touch ups a snap.  As long as the edge has not been damaged, it’s quick and easy work to re-establish a keen edge on the secondary bevel with a few strokes on a sharpening stone.

On a bevel down plane, adding a secondary bevel affects no change in the angle of cut.  The only thing it changes ever so slightly is the relief angle – the angle between the back side (bevel side) of the iron and the work surface. It also slightly reduces the total bevel angle on the iron itself, but should not be enough to affect durability of the edge.  On most planes the addition or subtraction of a couple of degrees of bevel angle is not going to make any difference.

Some people will tell you you can’t (or shouldn’t) put a secondary bevel on a bevel up iron.  That’s nonsense.  If you’re that concerned with the cutting angle, sharpen your primary angle a few degrees shallower so the secondary angle brings you back to 25º.  I’ve never experienced a problem with a secondary bevel on a bevel up iron, and it’s a sharpening technique I apply consistently.

Back Bevels – Back bevels can be added for a couple of reasons.  On a bevel down plane, (unlike the secondary bevel) adding a back bevel will affect the angle of cut.  This is something you can use to your advantage.  For example, with the frog fixed at a 45º angle, adding a 5º back bevel increases the angle of cut from 45º to 50º.  This technique can be used if you’re working with harder woods or wood with difficult grain.

Back bevels are also helpful if your plane’s iron has rust damage or pitting to its un-beveled side.  By putting a back bevel of 1º to 2º on the pitted back side, you effectively cut through the pitted surface creating a clean, undamaged edge.  You end up with a cutting angle of about 46º to 47º – not a critical difference for most woodworkers.  If you’re obsessive about your edge geometry and angle of cut, this might not be a satisfactory solution.  Although if that’s the case, you probably shouldn’t be futzing with a vintage plane in the first place, let alone salvaging a pitted plane iron.  But if you’re like me, having one or two extra irons set up for different purposes is a must, and finding good use for old irons suffering from age and neglect makes me feel good.  It’s just a matter of purposing them for the right job.  And again, increasing this angle of attack is actually advantageous when planning wood with difficult grain. [3]

Back bevels on bevel up irons won’t change the angle of cut, but they do change very slightly the relief angle and the bevel angle of the iron itself.  Again, a couple of degrees difference should not adversely effect the  durability of the edge.

Summary

Wrapping up, the vast majority of both bench and block planes can be sharpened with a 25º bevel angle.  However, with a little experimentation, you may find that making some adjustments to the geometry helps overcome challenges presented by both difficult wood and less than perfect plane irons.  Don’t be afraid to experiment.  That’s the best way to learn.

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[1] Hock, Ron, Back Bevels and Plane Geometry, 2010.
[2] Whelan, John, The Cutting Action of Plane Blades, 1993.
[3] Hock, Ron, Back Bevels and Plane Geometry, 2010.

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Tune Your Hand Plane Tonight

Among the most frequent web searches that lead people to this site come from those looking for information on tuning a hand plane.  Admittedly, for those new to the craft, or at least new to using hand tools, the prospect of setting up and fine tuning a hand plane is daunting.  After all, the nomenclature of parts is bewildering, the functional mechanics are an exercise in geometry and physics, and then there’s that whole issue with sharpening.  It’s no wonder so many people would rather spend an evening prepping for a colonoscopy.

But yea I say unto you, fear not!  Tending to a neglected (or new) hand plane is both relaxing and rewarding, and in most cases takes just an hour or two.  Best of all, the gratification is instant, the rewards immediate.

Now in the interest of keeping things simple, I’m going to assume that your plane is already in a mechanically functional condition and doesn’t require a full blown restoration.  For that level of detail, I recommend reading the posts under Preservation on the menu bar at the top of the page.  I’m also going to focus solely on bench planes.  I’ll cover black planes in a later post.  For simple tuning in one evening, read on…

Step 1 – Pour Drink of Preference

PVW-trio-4What you drink is up to you, and moderation is certainly recommended, for while you won’t be working with powered tools, you will be handling very sharp objects.  I personally prefer a finer bourbon, perhaps Maker’s 46 or Elijiah Craig 18 year, or if I’m in a particularly festive mood, a little Jefferson Presidential Select 17 year or Pappy Van Winkle.  Either way, begin by putting on some relaxing music and have a drink.  (5 minutes)

 

Step 2 – Disassembly & Cleaning

Disassembled Plane, Ready for TuningThe second step is to completely disassemble your plane and clean all the parts.  Using screwdrivers of the appropriate size, remove all the parts, screw, bolts, washers, etc.  If you’re not completely familiar with what and where everything goes or are worried you might have trouble putting it all back together, take pictures or notes.  Or just pay attention; it’s not that complicated for heaven’s sake.

Once disassembled, brush off all the sawdust and dirt.  If the filth is excessive, use a toothbrush and orange degreaser (available at the hardware or grocery store).  Also take a few minutes to clean the threads and slots on all the screws and bolts.  I use a small wire bristle brush with a little turpentine or light penetrating oil like WD-40. Once cleaned, wipe them down and set them out of the way so they don’t attract grit.  (10 minutes)

Step 3 – Inspect the Sole

Stanley No. 7 Jointer PlaneTake a look at the sole (bottom) of the plane.  Put a straight edge against it if it makes you feel better.  Once you’ve convinced yourself that it’s flat enough (which it undoubtedly is), set it aside and have another drink.  Seriously, after owning hundreds and using dozens of planes over the years, I’m convinced it’s rare to come across one with a sole so warped, cupped, or bowed that it’s unusable.  If there are any dents or dings with raised points around the edges that risk digging into your wood surface, carefully file them flat with a mill file, followed by a little 220 grit sandpaper.  You can also use the sandpaper or steel wool to remove any heavy crud – I suggest lubricating it generously with WD-40, Mineral Spirits, or Turpentine.  Working against a dead flat substrate such as a granite or the iron bed of a table saw is recommended.  Go easy.  No need to overdo it; you just want it to be clean and smooth.  (5-30 minutes depending)

Step 4 – Address the Frog

Lap frog face on edge of stone to protect yokeFirst inspect the seat for the frog on the top side of the plane’s base.  This is the area of contact where the frog attaches to the body of the plane.  The mating surfaces must be clean and flat.   Use a toothbrush with the degreaser.  If there is stubborn crud to be removed, use a brass bristle brush.  If the crud is really bad, you can use a small steel brush, but be very careful to to damage the surrounding finish.  Mating surfaces on the frog itself should also be cleaned in the manner described above.

The face of the frog is one of the more critical surfaces of the plane.  It needs to be as flat as you can get it so the iron sits completely flush against.  You don’t want any wiggle or movement, so any high spots or irregularities in the casting need to be filed or sanded flat.  I go back to my granite surface and sandpaper for this.  Taking care not to damage the tip of the yoke that engages the iron and cap/iron, carefully sand the face surface of the frog until it is as flat as possible.  Change directions periodically to keep it even.  You only need to do enough to ensure the iron sits flat against it.  (15-30 minutes)

Step 5 – Polish the Cap Iron

Cap IronThe leading edge of your cap iron (also called the chip breaker) will need a little attention.  Flatten the leading edge of the cap iron where it contacts the iron so that it seats completely flush against it.  You don’t want any gaps that shavings can slip through.  While you’re at it, polish the top side of that leading edge as well (the hump) to make it nice and smooth.  Less friction makes the shavings pass over it more easily, helping to prevent clogs.   The smoother the better, but don’t obsess over this step.  (10 minutes)   

Step 6 – Sharpen the Iron

Sharpening SetupYes, I know, the step everyone loves to hate.  Even for me, it’s often a task that I procrastinate over, but once I get going, I actually enjoy it.  Since this is not a sharpening tutorial, I’ll leave the particulars on methodology to another post or reference.  But if you do nothing else, take the time to put a keen edge on your plane’s iron.  A 25 degree bevel works perfectly on bench planes; add a micro bevel if you’re into that, and don’t forget to polish the unbeveled back edge. (30 minutes)

Step 7 – Lubrication

Pure Oil 1Lubrication is a good idea, but should be done sparingly since oil attracts dirt and grit.  I add just a drop of light oil to the threads of all the bolts and screws before re-installing them.  I also add a drop to all the moving/adjustment parts, but wipe them with a rag afterward so that only a light film is left.  They certainly don’t need to be dripping.

Some guys believe in waxing the sole.  Nothing wrong with that as long as you don’t use a silicone based wax.  However, I just wipe down all exterior surfaces with a little Jojoba oil for storage.  (5 minutes)

Step 8 – Assemble, Adjust, Cut

Stanley Bailey no. 5, Type 17 - WWII VintageTime to put it all back together.  Re-attach the frog and all its related hardware first, but don’t tighten just yet.   Put the knob and tote back on if you took it off.  Carefully put the iron and cap iron assembly in place and install the lever cap.  It should lock down securely, but not so tight as to inhibit raising and lowering the iron.  Adjust the frog forward or backward as needed until the iron’s cutting edge is positioned appropriately for the type of planing you intend to do (see open vs closed mouth).  Once set, tighten down the frog and lower the iron into the mouth to take your first test cut.   All of your hardware and adjustment mechanisms should move freely and smoothly. (10-15 minutes)

Unless you run into an unexpected problem, the entire tuning and sharpening process can be completed in about 1-1/2 to 2-1/2 hours, and even quicker if you’re tuning a new plane or re-tuning a plane that has already been tuned or well cared for.  It’s easy, rewarding, and builds both knowledge and confidence in your ability to master hand planes.

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Wait!  What about the tote and knob, you ask?  You can read all about their care and repair right here.

Hand Planes for The Rest of Us

A very utilitarian workbench under construction in a less than ideal work space

Seems like most of information related to using hand planes today tends to lean toward the puritanical.  The vast majority of instructional material is written for those planing rough boards straight from a sawmill.  Certainly, there is a good deal of logic behind this.  After all, hand tool purists prepare their wood from the roughest of cuts, be it from saw or froe. For them, the three bench plane model makes complete sense.

That said, there are an awful lot of folks out there in the midst of transitioning from powered to hand tools, and many more who, while using hand tools to some degree of exclusivity, work primarily with dimensional lumber due to constraints of time and available space.  In some cases, a project may include a combination of both.  I often use dimensional lumber for drawer carcasses for example, in order to save time.  The fact is that working rough lumber is not always practical.  I know men and women who are passionate about their craft, but have to move the car out of the garage just to get to the saw horses they use as a bench platform.

Taking a momentary step back, the traditional three bench plane system consists of a Fore Plane, Try Plane, and Smoothing Plane.  Used in sequential steps of coarse, medium, and fine, you can take just about any slab of tree and turn it into a finished board.[1]  Yet while that works perfectly for woodworkers preparing rough cut wood straight from the tree or mill, it doesn’t make much sense for those using dimensional lumber.

Dimensional lumber, of course, is the pre-surfaced wood you find at your local home center, etc.  1x2s, 2x4s and the like are all dimensional lumber.  The wood has been processed through commercial planer and jointer machinery to make it a consistent and standardized size.  And while it’s far more expensive than unprepared wood, it’s often more practical for small singular projects or when wood storage is simply not an option.  I will confess right now to using dimensional lumber for many of my own smaller projects.

Even though dimensional lumber is pre-surfaced, it still requires some degree of final finishing.  Further, the wood still needs to be cut, trimmed, jointed, etc., in order to construct whatever it is you’re working on.  I use my hand planes, hand saws, brace, and chisels to do as much of work as possible, but the workflow tends to be a little different than when I’m preparing rough lumber.

With dimensional lumber, there’s really no need for the coarse step of flattening with a no. 5 fore plane.  For most smaller surfaces that have not been edge joined (panels and tops), a quick pass with a very finely set smoothing plane, card scraper, or scraper plane is usually all that is required.  For glue ups, I use my no.7 try plane with a straight beveled (no camber) iron to prepare the edges to be joined.  I also use my no. 7 with a slightly cambered iron to level out uneven joints before moving to the smooth plane.  Again, a very fine set is all that is needed.

For everything else, the same rules apply as when working rough lumber.  For the occasional woodworker interested in getting started with hand planes, or for those who work mainly with dimensional lumber, you might still want the three fundamental bench planes – the no. 4, no. 5, and no. 7, but you won’t likely use them in the same manner as you would if preparing rough lumber from the mill.

The point is, don’t avoid hand planes simply because you work with dimensional wood.  Just understand that you’ll be using them differently than you would if you were preparing rough lumber.  And don’t be ashamed of using dimensional wood if it’s more convenient or practical for your work space.  It may not be the most economical way to go, but it’s better than missing the opportunity to work wood at all.

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1. Christopher Schwarz, Coarse, Medium, and Fine.

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Open vs. Closed? Mouth vs Throat? – The Adjustable Plane Facts

Adjustable Mouth?  Open or Closed Throat?  Say what?

What’s all the ruckus about adjustable mouth planes? What are they? Do I need one? How do I use it? What’s the difference between adjustable throat planes and adjustable mouth planes?  Good grief, it’s enough to give any new galoot a headache!

Stanley no. 60 with mouth open on left; Stanley no. 18 with mouth closed on right.

What’s the difference?  To clear up the confusion, let’s start with the nomenclature. Both ‘adjustable throat’ and ‘adjustable mouth’ actually refer to the same feature. Both terms are used interchangeably, which is confusing and in my opinion, technically incorrect. The mouth is the rectangular opening that you see when looking at the bottom of the plane. The throat is the area above the mouth on the top side of the plane. The part that is adjustable is the mouth, not the throat.  That said, even Stanley wasn’t consistent in its terminology, listing ‘adjustable throat‘ planes in their catalogs some years and ‘adjustable mouth‘ planes other years.  Far be it from me to argue the point one way or the other, but for the rest of this post, I’m sticking with adjustable mouth.

What is it?  An adjustable mouth on a plane means that the size of the mouth opening can be adjusted, i.e., opened to make it larger or closed to make it smaller. Typically, this is accomplished by sliding the toe section of the plane forward (away from the iron) to increase the size of the mouth opening, or backward toward the iron to decrease it.

Not all planes have adjustable mouths. In the world of vintage tools, adjustable mouths were most commonly featured on the various manufacturers’ premium lines of block planes and a few of their specialty planes. Modern manufacturers like Lie Nielsen and Veritas understand the value of adjustable mouths to woodworkers and feature them on many of their bench planes as well their block planes.

Why do I need it?  The value of having an adjustable mouth on a plane is the ability to increase or reduce the space between the leading edge of the mouth opening and the cutting edge of iron. If you’re making a heavy cut and taking thicker shavings, you want more open space in front of the iron for the shaving to pass. If you’re making a fine cut, taking thin shavings, you need less space in front of the iron.  In fact, you want the opening to be just marginally larger than the thickness of the shaving.

How do I use it?  In practice, the leading edge of the mouth presses down on the wood fibers as you make a cut. Having a ‘fine set’ to your plane (meaning a closed mouth and very shallow depth of cut) keeps the wood in front of the iron tightly compressed.  This enables a very thin shaving with less chance of tear out, in which the wood fibers split well ahead of and below the cut. Opening the mouth accomplishes just the opposite. With less compression, the iron is able to take a thicker cut, and the larger opening allows the shaving to pass through unobstructed up into the throat area.

Naturally, the size of the mouth opening is only half of the equation – you also need to decide how far down to extend the iron based on how deep you want to cut. If you try to take a heavy a cut with the mouth too tightly closed, the shaving will be too thick to pass through the opening and will quickly clog the mouth opening or simply come to a screeching halt.  This effect can be more or less pronounced depending on the type of wood you are working on.

The trick, of course, is finding the right balance between set of the iron and opening of the mouth, but this is truly not as difficult as it might sound. A little trial and error will quickly build experience and give you a ‘feel’ for how to set your plane for the cut you desire. Once you have it set appropriately for what you’re trying to accomplish, the results will be superior to what you would get from a plane with a fixed aperture mouth, which lacks the flexibility for making fine adjustments to the cut.

As a final thought, it is worth pointing out that many planes without adjustable mouths can still be adjusted.  Virtually all bench planes have adjustable frogs.  Moving the frog forward or backward decreases or increases the size of the mouth opening, accomplishing the same goal as an adjustable mouth, even if the process is a little more involved.  Still, that is precisely why Stanley added the frog adjustment feature to their planes in 1907.

Unlike bench planes, the frogs of block planes are fixed, so unless they have an adjustable mouth, you’re stuck with the fixed size opening.  This is why adjustable mouth block planes are more highly regarded and valued by woodworkers.

Common* Vintage Planes with Adjustable Mouths

Stanley nos. 9-1/2, 15, 16, 17, 18, 19 standard angle block planes
Stanley nos. 60, 60-1/2, 65, 65-1/2 low angle block planes
Stanley no. 62 low angle jack plane

Millers Falls nos. 16, 17, 26, 27, 36, 37 standard angle block planes
Millers Falls nos. 46, 47, 56, 57 low angle block planes

Sargent nos. 306, 307, 1306, 1307, 4306, 4307, 5306, 5307 standard angle block planes
Sargent nos. 606, 607, 1606, 1607 low angle block planes
Sargent no. 514 low angle jack plane

Modern Plane Makers

Lie-Nielsen – makes block plane models with adjustable mouths
Veritas/Lee Valley – makes both block and bench planes with adjustable mouths
Stanley – makes modern variations of their vintage counterparts
Wood River/Woodcraft – makes block plane models with adjustable mouths

* This is not a complete list, but includes the most common planes for use.

For more information on plane nomenclature, please refer to the Plane Terminology page for a full dictionary of plane parts and terms.

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Deconstructing the Wright Flyer

I spent this past week on vacation at the beautiful Outer Banks of North Carolina.  The OBX is one of my favorite places on earth, and I’ve been visiting just about every year for the past 30 years.  Despite its growth and development, especially over the last 20 years, there is still something raw about the Outer Banks.  Mother Nature may have yielded some of her land, but the spirit of the place is still very much wild, a precarious thin line of sand at the mercy of the Atlantic Ocean.  It was here, on the sandy dunes of Kitty Hawk and Kill Devil Hills back in December of 1903, that Orville and Wilbur Wright first flew a heavier-than-air craft under its own power.

Kitty Hawk CampSitting on a dune deck overlooking the Atlantic just a few miles from Kitty Hawk this week, I got to thinking about just what kind of tools the Wright brothers might have used when building the Wright Flyer.  The plane’s wings were constructed of spruce and ash covered with muslin.  The rest of the frame was metal, not at all surprising considering the Wrights were machinists, not woodworkers.  After all, they designed and developed the Flyer in their Ohio bicycle shop.  They favored coastal North Carolina for its windy dunes and because it was remote – competition for flight was intense and they didn’t want a lot of press at that point.

Fortunately, the construction of the plane has been exhaustively researched and documented, not a task as simple as one might assume since the Wrights were very secretive, didn’t keep detailed plans of the design, and constantly made changes on the fly (no pun intended). [1]  The plane’s framework “floated” within fabric pockets sewn inside, making the muslin covering an integral part of the structure. This ingenious feature made the aircraft light, strong, and flexible. The 1903 Flyer was powered by a simple four-cylinder engine of the Wrights’ own design.  To fly the airplane, the pilot lay prone with his head forward, his left hand operating the elevator control. Lateral control was achieved by warping the wing tips in opposite directions via wires attached to a hip cradle mounted on the lower wing. The pilot shifted his hips from side to side to operate the mechanism, which also moved the rudder. [2]

Wingspan: 12.3 m (40 ft 4 in)
Length: 6.4 m (21 ft)
Height: 2.8 m (9 ft 3 in)
Weight, empty: 274 kg (605 lb)
Engine: Gasoline, 12 hp
Manufacturer: Wilbur and Orville Wright, Dayton, Ohio, 1903

Construction

Wright Cycle ShopMy interest in the Flyer was centered on the woodworking tools and techniques that might have been employed.  However, in researching the Wrights, their shop, and the Flyer, it became clear that the woodworking aspect of the plane’s construction was incidental at best.  Obviously the focus (both then and now) was on the science – weight, power, aerodynamics, and control.  Records of their workshop reveals it was sparse with relatively few tools, and those tools they had were mainly dedicated to metal work.[2]  The bicycle shop had a 14″ Putnam Lathe, a 20″ Barnes drill press, and a 26″ Cresent bandsaw.   References confirming this are attributed to a book, “Charles Taylor, Mechanician.”  Taylor, of course, was the man who built the aluminum engine specifically for the Flyer.

Orville Wright at work in ShopThe propellers, wing struts, and wing framework were the only parts of the aircraft that were made of wood.  Since the Flyer was designed to be portable, joinery was all temporary and removable, using clips and brackets that were fabricated of metal.  In fact, it can be assumed that the decision to use of wooden components was probably based on practicality.  Orville and Wilbur wanted to keep the weight and cost down, and wooden parts were easy to replace if broken.  Lightweight metals like aluminum, which was used for the engine, were still comparatively expensive at the turn of the century.  Parts made of Spruce were strong, lightweight, and cheaply replaceable.

While I could not find any direct reference to the woodworking tools and techniques employed to make the wooden parts of the plane, looking at detailed photos of the components provides some insight.  With the exception of the propellers, which were hand carved, the rest of the parts were fairly simple and utilitarian in both design and execution.  Also, given the fact that the Wright Bicycle Shop was a metalwork business, and the Wrights were cheap about their outlay for tools and equipment, it’s safe to assume that the wooden components were formed using the most basic of woodworking hand tools – Saws, planes, spokeshaves, and chisels.

Wright Shop Tools

It turns out that, from a woodworking perspective, the most interesting component were the propellers.  As mentioned, the propellers were carefully hand carved to achieve the greatest possible efficiency.  The Wrights thought propeller design would be a simple matter and intended to adapt data from shipbuilding.  However, their library research disclosed no established formulas for either marine or air propellers, and they found themselves with no sure starting point. They discussed and argued the question, sometimes heatedly, until they concluded that an aeronautical propeller is essentially a wing rotating in the vertical plane. On that basis, they used data from more wind tunnel tests to design their propellers. The finished blades were just over eight feet long, made of three laminations of glued spruce. The Wrights decided on twin “pusher” propellers (counter-rotating to cancel torque), which would act on a greater quantity of air than a single relatively slow propeller and not disturb airflow over the leading edge of the wings.[3]

Wilbur Wright At Lathe c. 1897The propeller blade is shaped like an airfoil and there is a pressure difference created across the blade because of the motion of the spinning blade. The pressure difference causes large amounts of air to be accelerated through the plane of the propeller and the reaction of the vehicle to this motion generates a force called thrust. The thrust pushes the aircraft forward in accordance with Newton’s first law of motion.  The use of high speed (~350 revolutions per minute), thin propellers on their aircraft was one of the major breakthroughs for the Wright brothers and allowed them to succeed where others failed. At the time, others employed low speed, thick bladed propellers, much like the blades of a wind mill. But the brothers correctly determined that high speed, thin propellers are more efficient than low speed thick blades. [4]

Fortunately, the Wright Flyer was a far more impressive piece of engineering than it was an example of turn of the century woodwork.  Call it a little vacation inspired curiosity, but I enjoyed exploring this important piece of history this week.  If you’re lucky enough to visit the Outer Banks, I highly recommend a trip to the Wright Memorial National Park at Kill Devil Hills.  Following an afternoon at the park, make sure you drive down Collington Road to Billy’s Seafood, one of the area’s more recent national treasures.  Best steamed crabs on the beach!

Steamed Crabs

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1. The Wrights left an obscure trail to follow, carefully guarding their findings and working in secrecy. As a result, little is available in the way of blueprints, designs or instructions. – http://www.countdowntokittyhawk.com/flyer/2003/construction.html
2. National Air and SpaceMuseum, http://airandspace.si.edu/exhibitions/gal100/wright1903.html
3. Wikipedia http://en.wikipedia.org/wiki/Wright_brothers
4. Nasa, http://wright.nasa.gov/airplane/propeller.html

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Millers Falls Plane Specifications

Specification charts for Millers Falls planes have now been added to the site under the Tools menu.  Included are charts for bench planes as well as block and specialty planes.  These charts provide Stanley equivalents where applicable.

There is also a bench plane conversion chart cross-referencing planes made by Stanley, Sargent, Millers Falls, and Record.  I plan to have additional information available in the near future, including comprehensive information on both Millers Falls and Sargent.  In the meantime, enjoy!

Millers Falls page
Bench Plane Specifications Chart
Block Plane Specifications Chart
Plane Cross Reference Chart

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