|Forum topic by Jeff_F||posted 06-21-2010 03:34 AM||17031 views||5 times favorited||39 replies|
06-21-2010 03:34 AM
I recently attended a weekend workshop at the Marc Adams School of Woodworking on the use of hand planes. The workshop was presented by Thomas Lie-Nielsen and Chris Schwarz. Neither Chris nor Thomas needs any introduction, but just in case … Thomas Lie-Nielsen is the founder of Lie-Nielsen Toolworks and has revitalized the hand plane tool market. Lie-Nielsen hand planes are based upon the original Stanley plane designs but he has taken them to a new level in terms of construction and functionality. Chris Schwarz is the editor of Popular Woodworking Magazine and has re-energized the use of hand tools in woodworking.
After returning from the workshop I was talking to some friends about the class and mentioned that I walked away with the question of ‘why would anyone buy a bevel down plane anymore?’ I decided to put together a short write-up about this topic and post it on the forum to generate some discussion.
The workshop dealt with the use of hand planes. We learned how to sharpen a plane blade depending on its intended use – hogging off wood, jointing a surface or edge or smoothing a surface. We learned about the setup of a plane and how to tune a plane you might find at a flea market (a good old trusty early vintage Stanley) or one that is new right out of the box. We learned about the process to dimension a rough piece of wood to make it 4-square and ready for joinery. But, the best part of the workshop was the discussion about the types of planes, their components and construction, and the evolution of the hand plane. We learned about the relationship between the angle of the cutting bevel and the opening of the plane mouth and the size of shaving that can be produced and the quality of the cut. It was during this discussion that Chris made the statement “… the cap iron (aka chip breaker) on a bevel down plane was required to strengthen the thin blades used in the early days, but really doesn’t play a role in creation of a shaving…” That got my attention … let me explain.
One of the key differences among planes is whether the blade is inserted into the plane with the bevel facing up or facing down. The most well known planes are the ones with the bevel down and shown in the first picture.
In this type of plane the blade and cap iron are screwed together with the edge of the cap iron ‘somewhat’ close to the edge of the blade and then inserted into the plane with the bevel facing down. The blade and cap iron rest on a platform called a frog which is set at a particular, fixed angle. This combination is held in place with the lever cap. The next figure is a close-up of this arrangement.
Finally, this whole mechanism can be moved forward or backward to adjust the size of the mouth opening by adjusting a set of screws as shown in the following picture.
The other types of planes are the ones with the bevel facing up. These have been around for a long time as well but have become more popular because of the improved quality that is available today. In this type of plane, there is no cap iron and the blade is inserted into the plane onto a fixed, non-moveable, platform with the bevel up. Here is a picture of a typical bevel up plane.
The plane’s mouth is adjustable by loosening the front knob and sliding the base of the plane forward or backward. There is a small knob which can be set to limit the travel of the base.. Here is a close-up.
So, why is any of this important? It’s all in the angle and it’s all in the opening!!
As I mentioned earlier the thickness of the shaving and the quality of the cut are dependent on the angle of the bevel and the size of the mouth’s opening. The normal (typical) cutting angle is about 45 degrees for most woods but this can cause tear-out in highly figured wood or wood with wild grain patterns. You can use a higher cutting angle, 50 degrees or even 62 degrees, to reduce the tear-out. Also, normal practice is to close-down the mouth of the plane to just greater than the size of the shaving that you are going to produce. (The size of the shaving and the type of plane to produce it could be a whole other article)
Well, this finally brings me to Chris’s statement about the cap iron. I was always under the impression that the cap iron (aka chip breaker) broke up the chips and helped form the shaving. Not true! Chris’s recommendation was to set the cap iron close to the cutting edge but far enough back from the edge so that it would not clog the mouth. If that is the case, why would I ever buy a bevel down plane again?
The bevel down plane is much more complicated to set up than a bevel up plane. You have the blade and cap iron that must be matched with no gaps to make ensure that is doesn’t clog with small chips. The cutting angle is adjusted by replacing the frog with one of a different angle, at a significant cost (e.g., $75 for a new frog for my smoother plane) and the mouth size is adjusted by a trial-and-error approach by turning the screws to move the frog mechanism.
By contrast, the cutting angle of a bevel up plane can be easily adjusted by honing a secondary bevel on the plane blade. If the blade bevel is ground to 25 degrees (typical) a secondary bevel can be honed at 30 or 40 degrees very easily. You can also purchase additional blades (for less than half the cost of a frog) and grind and hone to whatever angle you desire and just switch blades as necessary. Finally, the plane’s mouth is easily adjustable by sliding the base forward or backward. This type of plane is extremely flexible and easy to setup for various planning situations.
Therefore, I pose the question …”Why would I ever buy a bevel down plane again”?
-- Jeff, www.jeffswooddesigns.com