Deciding Factors
There are many factors to consider when choosing a scroll saw blade for your project. Thickness and hardness of wood as well as intricacy of the pattern are all things to be weighed.
The first thing you must look at is the intricacy of the pattern. You will need to chose a blade that is small enough to be able to cut in the tightest areas of your pattern without giving you too much trouble. Generally with thicker and harder wood you will want bigger blades however the blade you use must be able to turn within the radius of the sharpest corners of your scroll saw pattern.
Scroll Saw Blade Size Numbers
Scroll saw blade sizes are listed using numbers. The higher the number, the bigger the blade is. The numbers can range from as large as #12 to sizes below #0 such as #2/0 (pronounced two aught), #3/0, etc. Generally you won’t be needing anything that’s smaller than #3/0 as they are usually considered jeweler’s blades.
Bigger blades will be both thicker and wider as well as, on average, having less teeth per inch. There is no standard governing these specifications however so there will be slight variation between manufacturers as well as between different series of blades by the same manufacturer.
Size of the blade is not the only thing that affects its ability to turn. Different manufacturing techniques make similar looking blades that behave vastly different from each other and some experimentation may be required to find what brands/series work best for you. A good example of this can be seen by the difference between stamped blades and precision ground (PGT) blades. PGT’s are slightly more expensive but they will start sharper and stay sharp longer than stamped blades. They also lack a burr on one side from the stamping process which makes them cut perpendicular to the blade rather than 10-15 degrees to the right like most stamped blades do. That being said, my favorite blades are stamped. I use them because I am comfortable with them and have yet to find another blade that’s as easy to control as these.
Regular Tooth – The basic scroll saw blades. Relatively high TPI (teeth-per-inch).
Hook Tooth – Teeth have a positive rake and blade cuts aggressively. Great for thicker material.
Skip Tooth – Like a regular tooth blade but with about half the TPI. Slower cutting, better chip removal. Blade will stay cooler.
Double Tooth – A hybrid of regular and skip tooth. Teeth are in groups of two followed by a gap.
Reverse Tooth – Like a regular tooth blade except the last inch of teeth are pointing in the opposite direction. This makes for cleaner cuts on the back of your work to minimize burrs and reduce sanding time after cutting. When mounting these blades, position them so that only about two reverse teeth cut into your wood when the blade is all the way up.
Full Reverse Tooth – Every third tooth in the opposite direction. Has the virtually the same behavior as the regular reverse tooth.
Crown Tooth – Similar to the full reverse tooth blades, crown tooth blades have every second tooth in the opposite direction.
Spiral – These blades are effectively a normal blade that has been twisted into a spiral so that all sides have teeth. They cut in any direction and thus require a little bit of practice to get used to them. Having teeth on all sides means they will make much wider cuts (thicker kerf lines) however you can cut bigger pieces on the saw more easily because you don’t have to constantly spin your work piece around on the table. Highly detailed portrait patterns are best cut with spiral blades.
Flat End Spiral – Same as spiral but with flat ends for easier installation in the saw.
Reverse Spiral – Same as spiral but with every third tooth or the last inch of teeth in the opposite direction for cleaner cuts and less burrs as illustrated in both examples above.
Metal Cutting Blades – Higher TPI for cutting metal.
Conclusion
All in all, as you work with the different types of scroll saw blades and experience them first-hand, you will be able to better choose the blade that is right for your project and also one that you feel most comfortable working with. I hope these general guidelines will be helpful in getting you started and choosing that perfect blade.