The snow has melted and the Breede River is starting to gently flow again. Although it is pretty cold here at night, the stars are awesome, the air is wonderfully crisp and the days are sublime.
This week I shall attempt to unravel the complexities of hand saws. Many woodworkers know very little about their saws and I hope that I can bring a bit more information to the table. In this blog, I am only going to deal with the traditional Western style of woodworking saws and I shall write a separate blog on the Asian style at a later stage.
Collection of Woodworking Saws in a Dedicated Till Cupboard
As always, it is important to first get the history into context.
A woodworking saw is simply a hand tool with a toothed blade used to cut timber. Our saws are amongst the oldest known tools and many of the developments and innovations that have been made in saws over thousands of years are still relevant to the hand saws we use today.
In the Paleolithic Period (between 60,000 and 10,000 BC) composite saws made of stone "bladelets" also known as "microliths" set into bone handles were made and used. During this period, the first Flint Saws also appeared.
With the discovery of copper, around 4,000 years ago, the first metal saw blades became possible.
With the advent of the Iron Age, the weaker copper and bronze were discarded and raked teeth became possible. During this period, woodworkers figured out that increasing the number of teeth in a saw, increased it's efficiency. (Clever chaps, our ancestors!).
Egyptian Pull Style Saw in use.
Small saws were used for carpentry and it is most interesting to note that the Asian style of Pull Saws that we love today, were widely used by the ancient Egyptians. Hieroglyphics discovered during Egyptian archeological digs demonstrate their use of this style of saw in their furniture making processes.
Ancient Egyptian Ceremonial Saw
As time progressed, adjustments in saw design were made according to a saw's intended application. For example, the spacing between the teeth and the depth of the gullets between the teeth allowed the saw to double as a "rake" after the cutting stroke, thus removing sawdust that would otherwise build up in the cut or "kerf", therefore helping the teeth to stay sharper, reducing heat build up in the saw blade and resulting in cleaner, more efficient cuts as well as longer periods between sharpenings.
Two Man Frame Saw used for Cutting Veneers
from Andre Roubo's L'Art de Menusier
(Note the use of a Double Screw or "Moxon Vise")
As metallurgy improved over the centuries, hand saws benefitted from many innovations.
During the 17th century the strongest saw blades were still extremely narrow. The most popular hand saw for woodworking in this era was the Bow Saw, which came in many sizes and styles. It was (and still is) named for it's similarity in structure to the Bow and Arrow, and it was the narrowness of the available saw blades that has kept this style of hand saw very popular right through to present days. (I have had my Marples 12" Bow Saw for over 40 years and it still sees very regular usage in the workshop).
Beautifully made Swan Neck Bow Saw
Howarth Cabinetmaker's Bow Saw
With the Industrial Revolution taking hold in Europe, much stronger and far more durable hand saws were produced. It was during this technical evolutionary phase that high grade, tempered tool steel was developed, and it was alloyed with certain other metals to produce far superior hand saw blades than were previously available.
Major developments in saw tooth design also happened alongside the remarkable metallurgical advances during this period.
Now that we have a little background, we need to get to the teeth of the matter:
Cross Cut Saws are used for cutting across the grain and Rip Cut are used for cutting with the grain. The specific tooth configurations apply to the purpose for which a saw is intended.
For example, if the angle of the teeth is too extreme, they will catch too heavily on the wood fibres and bring your sawing to a halt. At the other end of the scale, if the teeth angle is too shallow, the saw will not cut at all.
Cutting Stub Tenons with a Lie-Nielsen Tapered Tenon Saw
The teeth of a Cross Cut Saw (across the grain) are angled more obtusely than the teeth of a Rip Cut Saw, so that they are more effective in slicing the wood and not "chiselling" the wood. Conversely, the cutting edges of a Rip Cut Saw (with the grain) are set at right angles to the blade, so that the teeth actually cut like tiny square chisels.
The "set" of the teeth is the amount that they are bent away from the centre line of the blade. Heavy set teeth will cut a wide kerf and a light set will give a narrow kerf.
For Hardwood, the saw teeth should optimally be angled at 60º, while softer woods should be cut with teeth set at a more acute angle , which is generally accepted to be around 45º.
This is a rather grey area, as mentioned in previous blog entries, because of the varied requirements for Hard Softwood, Soft Hardwood, Kiln Seasoned, Air Seasoned and Green wood.
So what does all this tell us:
- Generally speaking, the less teeth per inch on a saw blade, the larger the teeth and the deeper the gullets will be. The nett result is that this aggressive type of tooth layout will remove large amounts of wood with each pass, the cut will be rough, will exhibit torn fibres and will require more effort to accomplish the cut.
- The more teeth per inch on a saw blade, the cleaner and neater the cut will be, but the drawback is that your cutting speed will be slower.
The various types of hand saws that we generally use as hand tool woodworkers are as follows:
Panel Saws - A = Pax Rip Saw, B = Pax Cross Cut Saw
Panel Saws are usually quite long, and do not have a spine. They are available in Rip Cut style and Cross Cut style. These saws are used to accomplish the initial aggressive cuts of your wood into rough sized pieces ready for planing. Rip Cut panel saws are generally longer than Cross Cut panel saws.
Lie-Nielsen Toolworks Carcass Saw
Carcass Saws and Sash Saws are the longest of the "Back Saws". All Back Saws all feature a spine made of either brass or steel. The spine acts as a weight and a blade stiffener, allowing a thinner blade to be used, thus cutting a thinner kerf when compared to a Panel Saw.
The heavier the spine, the less effort you will require to execute the cut. With less effort, comes the intended consequence of better cutting accuracy. Carcass and Sash Back Saws are filed for Cross Cut use and are designed for large accurate crosscuts in casework and sash window construction, establishing the walls of dados and cutting the shoulders of tenons.
- You should always adopt a "Three Finger Hold" on the handle of the back saw, with your index finger pointing down the length of the blade. Not only is this the most comfortable holding position, but extending your index finger helps dramatically with keeping the saw true, whether you are cutting dovetails at an angle or are cutting at 90º.
- DO NOT grip the saw as if your life depends on it!
- Hold the saw comfortably and confidently, never use the "white knuckle" approach.
- Saw using the entire length of the blade, don't do the short jerky dance! You paid for the entire blade, so use it!
- Don't position yourself on top of your work, sight down your arm to the saw, stand back and use your arm for purposeful cuts without forcing the saw down into the cut. Let the saw do the work.
- Always remember that the less time the saw blade spends moving within the cut, the cleaner and more accurate the cut will be. I cannot stress this last point enough!
- Some back saws available from the better makers feature a tapered blade (wider an the heel, narrower at the toe). This is a really great feature and has been around since 1900BC! The advantage of the taper is that when you are cutting a dovetail joint for example, if you maintain the spine of the saw absolutely horizontal during the cut, you will never accidentally cut past your base line on the opposite side of the board. Once you have cut down to the base line facing you, you can the tilt the saw forward slight and creep up carefully on the outer base line.
Crown Tools 12" Traditional English Bow Saw
Bow Saws come in a variety of sizes, from small frames that accept fret blades to large saws with wide and long blades. The most common size is 12" (305mm) and these saws are widely used today.
In my opinion, the best Mitre Box Saw available anywhere is the Nobex Champion. This saw is also a frame (bow) saw and can take a selection of differently toothed blades. Tension on the Nobex Champion is achieved by a threaded rod in the position that would normally be assumed by the twisted cord on a traditional frame saw.
Nobex Champion Mitre Box Saw
Flush Cut saws are really clever and very simple tools. Coupling a highly flexible blade with teeth that only have "Set" on one side, they excel at trimming dowels from your casework. Due to the singular set, the tool is used by placing the non -set side of the blade flush to the workpiece and sawing off the offending dowel. The result is that the blade does not damage the casework at all. These saws are inexpensive and do their job admirably.
Crown Tools Flush Cut Saw
Although power tools have pretty much replaced hand tools in many facets of woodworking, furniture makers, especially those who like to cut joinery in the traditional way, can simply not survive without their selection of hand saws.
There are many styles and sizes to choose from and yet there are only two traditional types of Western saw Tooth patterns: rip and crosscut.
As woodworking enthusiasts and professionals, we are extremely fortunate in South Africa to have all of the above saws easily available to us. When selecting a saw for yourself, always try it out, feel how it sits in your hand, feel it's weight and compare models and brands.
After all, you will be the woodworker doing the sawing, you should enjoy the process completely.
To understand the complexities of saw tooth geometry, I recommend that you follow this excellent downloadable PDF link by Joel Moskowitz of Gramercy Tools: Elements of Saw Tooth Design
Until next time, let's make shavings, not dust.