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Designing the best Block Plane

I believe that the unique quality of a block plane is it’s bevel up design.  This means that the cutting geometry of the plane is a function of both the plane design and the method to sharpen the blade.  On a traditional bevel down plane (like Stanley’s bench planes or the older wooden bodied planes), the angle that the plane cuts is dictated only by the bedding angle of the blade (usually between 40 and 60 degrees).  On the other hand, a block plane may have a blade bedded at 20 degrees, but sharpened at 30 making a total cutting geometry of 50 degrees.  

Today, bevel up planes are popular because they have such easily controlled cutting geometry.  If you want to cut end grain with a lower cutting angle, you sharpen your blade to 20 degrees and you’re cutting at 40 degrees.  If you’re planing figured wood and want to scrape more than cut, then you sharpen your blade to 50 degrees and you’re planing at 70 degrees.  This seems quite convenient, but historically doesn’t seem to be useful.  When sharpening by hand, it’s hard to control the exact angle of the bevel the way many modern woodworkers like.  Also, if you wanted a higher angle plane, you’d probably make a new wooden body for a blade you already have.  Historically, bevel up planes weren’t terribly popular because they could be fragile and more trouble than they’re worth, but they did exist.  The origin of the modern block plane probably comes from the earlier bevel up plane: the mitre plane.

The mitre plane was (usually) a metal bodied plane that built on the function of a strike block plane.  The strike block plane was a bevel down plane where the blade was bedded at a very low angle.  The lower blade angle made it good at shooting end grain and cross grain which is a similar operation to ‘blocking in’ which is where the block plane gets it’s name.  The strike block plane might get it’s name from the strike button on top of the plane that would retract the blade when hit with a mallet. Wherever it gets it’s name from, it was not a plane designed for longevity since the lower bedding angle for the blade made the sole very fragile where it supports the edge of the blade.  This led carpenters and plane makers to try making planes that are good for end grain without being so fragile.  

Strike block plane from

The answer was the mitre plane which flipped the blade upside down and tightened the mouth.  Unlike the strike block plane that worked well on end grain because the lower ‘shearing’ edge geometry requires less force and therefore creates less tearout, the mitre plane usually ended up planing at a similar angle as the common bench planes of the time (a 20 degree bed and 25 degree bevel is the same 45 degree plaining angle as most other planes).  Instead of reducing cutting force, the mitre plane localized the cutting force.  Usually tearout happens because the fibre of wood being cut is pushing against another fibre which pushes against another… until the whole chunk of fibres split off of the parent stock.  If the first fibre is presented to the blade and the second fibre isn’t allowed to move, then it doesn’t chip out.  The tight mouth of a mitre plane localized the cutting forces of the plane to an area less than half a millimeter in front of the blade.

The earliest mitre planes were made from wood and had tight mouths because of an endgrain block wedged into the toe of the plane.  Of course, making the plane out of wood doesn’t solve the fragile sole issue that the strike block plane had, so mitre planes quickly started being made from metal.

Wooden mitre plane from

It isn’t known exactly what the most common use of mitre planes was since there isn’t too much literature on them.  They may have gotten their name for being used on mitre jacks to clean up mitres, but the mitre plane is a very English plane design and the mitre jack is probably French or German and more recent.  Another hypothesis is that mitre planes were used for marquetry since they could handle the heavily figured exotic woods in the marquetry work that was gaining popularity in the 1700’s.  It’s also likely that they weren’t as common as we might think since a metal plane is far more likely to survive a couple centuries than a wooden plane, yet there aren’t terribly many mitre planes.  

The bevel up mitre plane may have had it’s brief fifteen minutes of fame, but it’s main advantage over other planes would be addressed by a much cheaper and more successful alternative.  In the mid 1700’s, the double iron plane started to become popular.  These are bevel down planes with a chipbreaker mounted above the plane.  This allowed carpenters to use plane designs that they were familiar with and didn’t involve the expense of an entirely metal plane.  At the end of the day, a chipbreaker does the same thing as the mitre plane’s tight mouth, but it doesn’t involve as much work to build, it was less expensive, and it was more versatile.  It would take another century or so for the bevel up plane to reemerge. 

Mitre planes from

In the early to mid 1800’s, New York City plane makers started making planes that were clearly inspired by the last stragglers of mitre planes from Spiers, Mattheson, or Norris that were still being made.  The NYC planes were bevel up designs that were almost indistinguishable from their English counterparts, but they increasingly started taking advantage of the New World’s manufacturing capacities.  Instead of gunmetal sides being dovetailed to a steel sole, the American planes were cast in one piece.  These planes, made by Napolean, Brandt, Thorested,… were marketed as piano maker and organ maker planes.  They undoubtedly would’ve been good with ebony and figured woods used in those trades, but they may also have been inspired by some early Holtzapfel planes that were designed specifically for organ building.  Someone at Stanley must have taken notice that there were other people in America making planes that had no obvious Stanley counterpart.  In typical Stanley fashion, there were two options: Stanley could either buy these companies or use their position as a pseudo-monopoly to put them out of business.  In this case, Stanley chose to design their own ‘Cabinetmaker’s block plane’ which they called the #9.  

The Stanley #9 is the first modern block plane, but it’s purpose is a bit unclear (unless putting entrepreneurs out of business is it’s purpose).  Logic would say that this is a plane that would be good at detail work in figured wood. Marquetry wasn’t very popular anymore, and Stanley advertised the plane to cabinetmakers instead of organ builders.  Additionally, the number 9 was a fully adjustable plane with blade depth and mouth adjustments, so the quality of cut was entirely up to the user and not the manufacturing of the tool.  The only hint to the use of the plane is the accessory it was sold with: a hotdog.

The hotdog was a metal hotdog shaped accessory that clamped to the side of the plane so you could hold the plane sideways.  This seems like a dead giveaway to the modern woodworker.  The plane was meant for use on a shooting board!  It has a square profile that would run well in the track of a shooting board, the hotdog makes it easy to use on it’s side, and the inspiration from mitre planes would make it excellent for end grain.  The only problem with this explanation is that the shooting board didn’t really exist yet and it would take at least a few decades to become commonplace enough for dedicated planes to be made for it.

Stanley number 9 from

Let’s get back on track.  We wanted a plane that’s good at end grain and figured wood without tearing out, so we made the strike block plane.  This had some issues, so we addressed them, then addressed new issues until we had a plane that was designed to be anticompetitive and only useful with technology that doesn’t exist yet.  Surely the next step in the evolution of the block plane will clear this up.  Stanley’s number 9-1/2 is their next block plane that built on the (poor) legacy of the number 9.  This plane was one of their most popular planes and was in production for over a century.  Just like the number 9, it was adjustable and had a bevel up iron.  That’s about where the similarities ended.  At least this plane has a clear purpose: it’s for blocking in.  Blocking is the process of trimming the end grain of short pieces of wood to help frame carpentry work.  This is similar to how Moxon described use of the strike block plane, but this time it’s purpose is more of a crude ‘plane it until you can cram it in place’ compared to the strike block’s more subtle ‘trim the piece until it’s a perfect fit’.  In either case, it seems we’ve come full circle to wanting a plane that is convenient to use in one hand and trims end grain using a bevel up iron and a tight mouth.

Stanley continued to create etymology for the name ‘block plane’  In 1905, they made the #62 (and later the 164) which is a block plane that would be terrible for blocking in.  This plane was 14 inches long and used both hands like a jack plane or panel plane.  This plane was a block plane because it was good for trimming end grain on butcher blocks.  I don’t think we’ll ever know what a block plane is meant to do or where they come from.  The only thing we can be sure of is that modern block planes are one handed bevel up planes, and they were always good at figured wood and end grain.

Stanley 62 from

What about the Ironbark block plane?  Which of these features is most important and how should the Ironbark block plane benefit from these qualities?  If I just wanted a plane that performed well on figured wood, I’d use a bevel down design bedded at 55 or 60 degrees with a good chipbreaker.  The higher bedding angle allows the plane to be used more before needing sharpening while the chipbreaker resists tearing and chipping.  If I wanted an endgrain plane, I’d go bevel up with a 40 degree bedding and a skewed blade.  Skewing the blade effectively lowers the cutting angle and allows for a more shearing cut.  These better options would’ve replaced block planes by now unless there’s another reason why people love them, and I think that reason is convenience.  A small one handed plane that fits in your pocket is far more useable than anything else because you can always have it with you.  The modern block plane doesn’t need to leave the best surface, or work particularly well on figured woods, if those features mean that it doesn’t work as well for heavy cuts or if sharpened infrequently (both issues with historic block planes).  Today, block planes are good for hybrid woodworkers who want to quickly put a chamfer on the edge of a table, or trim the endgrain of a dovetail. That is why the Ironbark block plane has a mouth that leaves a good surface with fine cuts, but doesn’t clog with heavier cuts, a 12.5 degree bedding angle that lets it slice through endgrain without tearing, a 1095 high carbon steel blade that stays sharp for longer than most block planes, and a small profile that is comfortable to hold and easily put in an apron pocket.

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