Hacksaws are a DIY staple that can cut a wide variety of materials. However, matching the correct blade to each application is essential for effortless cutting. This article explains the various types of hacksaw blades and their applications.
Let’s classify and compare blades in terms of hardness, coarseness, and the material they’re manufactured from. And finally, I will suggest the right hacksaw blade for cutting different materials.
So, let’s get to it:
Types of Hacksaw Blades According to Hardness
Hacksaw blades are primarily used for metal cutting and are made to varying degrees of hardness, matching the intended application. Hence, the primary classifications of hacksaw blades are all hard blades and flexible blades.
All Hard Blade
All hard hacksaw blades are fully hardened throughout the entire form including the blade body and teeth. They’re usually manufactured from high-grade tempered tool steel, and they tend to remain sharp despite prolonged use.
These blades are suitable for cutting tough materials, such as steel and other hard metals. However, the hardening process renders them brittle, and thus they break easily, often through brittle fractures.
Remember that, unlike other types of hand saws, the hacksaw blade is clamped on both ends and is tensioned. When using these blades, work carefully and wear the appropriate safety gear.
Flexible Blade
In the case of flexible hacksaw blades, only the teeth are hardened, not the entire blade. The blade’s backing is made from flexible sheet metal, rendering the blade far less brittle than the all-hard counterpart. This makes them better suitable for applications where flexibility is more important than hard-wearing qualities, such as cutting aluminum, thick steel bars, woodcutting, etc.
Flexible blades are often called bi-metal blades since they’re effectively made from two metals: a flexible sheet metal back and hardened teeth.
While a all hard blade would work fine with a smaller types hacksaw, you are better off with a flexible blade for your standard hacksaw.
- Related info: Different types of hacksaws and their frame sizes
TPI and Grade of the Blade
TPI refers to Teeth per Inch and indicates how aggressively the blade will cut. A larger TPI is suitable for harder materials, such as steel and other hard metals. Conversely, a lower TPI is meant for softer materials, such as brass, plastic, wood, etc.
Lower TPI (coarse blade) allows for a rougher cut, which works far quicker than a fine blade with higher TPI. This is because the coarse teeth are larger and has more chip clearance between the teeth.
Note that the workpiece’s cross-sectional thickness also influences the selection of TPI. While cutting, the blades should have at least 2 or 3 teeth in contact with the cutting edge. This is why you need to use a fine blade with high TPI when cutting sheet metal and copper pipes with small wall thickness although copper is a soft metal.
According to the number of teeth per inch, hacksaw blades can be classified as coarse, medium, fine, and super fine blades.
1. Coarse Blade
Coarse blades have a TPI of 14. These blades are meant to cut through workpieces with a 1” or greater cross-section. Coarse blades remove more material per cut than their fine counterparts and thus make quick work of most workpieces. These blades aren’t meant for smooth, delicate cuts. Instead, they’re meant to cut a workpiece to size before filing the edges to get them smooth.
Coarse blades are best suited to soft materials, such as plastic, wood, etc.
2. Medium Blade
Medium blades have a TPI of 18 and are meant to cut workpieces with a cross-section between ¼” and 1”. They remove slightly less material per cut than their coarse counterparts. They are suited to cutting harder material than the coarse blades.
18TPI hacksaw blades are good general-purpose blades that are suitable for cutting soft materials like plastic, soft metals like brass, and even mild steel. They’re not suited to cutting tough metals, such as tool steel, though.
3. Fine Blade
Fine blades with a TPI of 24 are best suited to cutting GI pipes, and sheet metal (both metal and plastic). These blades cut slowly, removing little material per cut, making for a smooth, clean cut.
The 24TPI fine hacksaw blade is suitable for cutting steel, cast iron, and other ferrous metals. You can also use this blade to cut soft materials, but the material removal rate will be much slower than a coarse or medium blade.
4. Very Fine Blade
Very fine blades with a TPI of 32 are meant for cutting extremely thin workpieces. These workpieces typically have a cross-section of less than 1/16” and require a smooth, delicate cut. Using a coarse blade on such thin workpieces will likely warp and tear the workpiece.
The 32TPI blade works well for copper tubing, electrical conduit, small diameter steel pipes, etc.
Woodworking hacksaw like Fret saw and coping saw also use fine pitch blades which delivers better finish and accuracy for fine woodworking.
Related info: Hacksaw vs Coping Saw comparison
According to Hacksaw Blade Material
Hacksaw blades are manufactured from various types of material, each with its own pros and cons and suited to specific applications.
1. High Carbon Steel Blades
High carbon steel blades are the standard hacksaw blade for cutting plastic, wood, aluminum, and other non-ferrous metals. These blades aren’t as hard-wearing as high speed steel blades, but they do the job in most DIY applications.
2. High Speed Steel Blades
High speed steel hacksaw blades are flexible and strengthened with molybdenum. Due to being double heat-treated, these blades have a hard cutting edge. At the same time, the back section is flexible and shatter-resistant.
HSS blades are ideally suited to applications requiring accuracy and high cutting rates. Their flexibility is essential for applications where the workpiece can’t be firmly secured, such as sawing off plumbing pipes during renovations.
High Speed Steel hacksaw blades make quick work of sawing through tough materials, such as tool steel, and high alloy steels.
3. Bi-Metal Hacksaw Blades
Bi-metal blades are made from two differing metals. Here, a molybdenum-enforced High Speed Steel cutting edge is electronically welded to a back section made of tough alloy spring steel. This combines a hard-wearing cutting edge with a flexible back to maximize cutting efficiency.
The chief advantage of the bi-metal construction is that the blades are highly flexible and are nearly shatterproof. This improves the life of the blade and lasts nearly 1.5 to 2 times compared to a regular HSS hacksaw blade.
Bi-metal blades are well-suited to cutting through most materials, including stainless steel and pipes and conduits made of nearly any material.
4. Carbide Grit Edged Blades
Carbide grit-edged High Speed Steel hacksaw blades are perfect for difficult cutting. Examples include cutting through perforated metal, thin gauge stainless steel, and wire rope. These blades help maintain a straight cut with their extended width, and they fit most hacksaw blades.
Another upside to these blades is that they are self-sharpening and can cut in both directions. This speeds up the cutting process since other blades can only cut in one direction.
Types of Hacksaw Blade for Different Materials
Hacksaws are used to cut a variety of materials across various applications. Each application is best matched to a specific type of blade – matching the correct blade to each application prolongs the blade lifespan and ensures easier cutting.
1. Hacksaw Blade for Aluminum
Aluminum is a relatively soft metal used to manufacture products of varying cross-sections. High speed steel (HSS) or high carbon blades are best suited to cutting aluminum. When cutting through bar stock and thick plates, use a blade with TPI between 14 and 18.
Cutting aluminum sheets or other workpieces with a thin cross-section requires a finer blade. In this case, use a blade with 32 TPI.
2. Brass, Bronze, and Copper
Brass, copper, and bronze are soft non-ferrous metals. These require medium to fine blades, typically manufactured from high speed steel. Bimetal blades could also work for these applications.
Generally, copper and brass require blades with 18 TPI, while bronze requires a 24 TPI blade. However, the cross-sectional diameter of the workpiece could also influence this.
3. Carbon Fiber
Carbon fiber is strong but lightweight and flexible. Using the wrong blade when cutting carbon fiber can cause the workpiece to warp or break.
The best option is to use a medium to fine blade when cutting carbon fiber, keeping the TPI between 18 and 24. Since carbon fiber is relatively high-wearing, a high speed steel blade will work.
4. PVC and Other Plastic
PVC and other plastics are relatively soft materials and typically require a medium blade with 18 TPI. A high carbon steel blade will work well here since the application doesn’t call for a hard-wearing blade. However, if you don’t have access to this, most other blades should work in these applications.
5. Stainless Steel
Stainless steel is a hard metal, requiring a fine or very fine blade, with a TPI of at least 24, but preferably 32.
Here, a carbide grit or bi-metal blade would work best, although a High Speed Steel blade could also work.
6. Wood
While it is not the best saw for cutting wood, you can cut wood with a hacksaw.
Wood is a soft material calling for a coarse hacksaw blade, with a 10 to 14 TPI (Teeth Per Inch). Here, a high carbon steel blade typically works, although this would result in a very rough cut. If you require a delicate, smooth cut, it would be best to use a different saw type since hacksaws aren’t meant for delicate woodwork.
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