Blade length
The total length of the hacksaw blade.
The value of this parameter is directly related to the saw type (see above). The general rule for choosing is as follows: the blade should be twice as long as the thickness of the largest workpiece that is planned to be sawn. This will provide an optimal range of motion to avoid unnecessary fatigue, and the tool, on the other hand, will not be too bulky. However, a long blade tends to spring back, so when working with hardwoods or other difficult-to-cut materials, shorter saws can also be taken. And in models with interchangeable blades (beam and jigsaw, some
mini-saws), length data will be required to search for spare blades.
In general, for simple household tasks for sawing wood, a length of 280 – 300 mm is considered optimal. For a private house with a garden, simple construction work, you should pay attention to larger models — up to half a metre. And the largest
two-handed saws can have a length of 1000 mm and even more. More detailed recommendations on the optimal blade length for certain tasks can be found in special sources.
Number of teeth per inch (TPI)
Density of teeth in a complete saw blade; measured as the number of teeth per blade length inch (TPI).
The higher the TPI, the smaller each individual tooth, and vice versa. Other things being equal, large teeth allow you to cut easily and quickly, but not very accurately; small — provide an accurate and clean cut, but at the cost of increased effort and time. Accordingly, when choosing a saw for this parameter, one must proceed from the fact that in this case it is more important — speed or accuracy. In addition, the TPI determines suitability for small workpieces: the smallest allowable log thickness is considered to be a three-tooth pitch. For example, in a 9 TPI saw, three teeth will take up 1/3", or approximately 8.5 mm.
It is worth remembering that only tools of the same type and purpose can be compared by the number of teeth per inch. So, for example, in standard saws for wood, the minimum TPI value is 4, and already in
passer saws — 9. The most coarse-toothed today are saws for foam concrete — they have about 1.2 – 1.8 teeth per inch; and the “record holders” in terms of density are saws for metal and
jigsaws, for which the TPI value of 24 is almost the standard.
Double-sided blade
A blade with teeth on both sides; in other words, instead of a butt, a second cutting edge with teeth is provided in such a blade. However it is worth noting that such webs are considered bilateral only if the teeth on different sides are different; interchangeable blades for archery and jigsaws that have the same sharpening on both sides (assuming that when one side is dulled, use the other) do not belong to this category.
The presence of two types of sharpening expands the capabilities of the saw, but the specific features of such an extension depend on the characteristics of the teeth on each side. For example, in some models, teeth of different sizes are provided on each side — large for quick sawing and small for neat; in others, one side of the blade is for ripping, the other for cross cutting, etc. The specifics of the
double-sided canvas in each case should be clarified separately.
