Hacksaws are popular hand saws used in various applications. With the right type of hacksaw blade, you can cut a wide variety of materials. But, what’s the proper direction of the hacksaw’s blade, and why does this matter?
Wouldn’t the saw work just as well with the blade in the opposite direction?
Let’s find out:
Teeth Direction of Hacksaw Blade
Hacksaw blades are generally installed with the teeth pointing down and forward. This means that the blade direction is such a way that it cuts on the push stroke.
Cutting on the push stroke allows you to exert more power, thus making quick work of the cutting process. It also allows for more accurate cutting since you can carefully guide the saw along the intended cutline.
Is a Hacksaw a Pull or Push?
Generally, hacksaws are designed for cutting on push.
In some cases, you would install the hacksaw blade in reverse, having it cut on the pull stroke. This is useful when cutting soft materials like rubber or very thin sections. Here, the blade experiences slightly more tension during the cut, decreasing the likelihood that it could wobble while cutting. A more stable blade ensures that the material surrounding the intended cut line isn’t damaged.
Since hacksaws have a D-frame, with the blade attached to it at either end, the blades are already tensioned. That’s why cutting metal on the push stroke is possible in the first place.
Hand saws such as Japanese woodworking saws with thin blades that aren’t tensioned would be installed to cut on the pull stroke to compensate for this.
Can Hacksaw Cut in Both Directions?
When cutting soft materials like plastic, the hacksaw can remove material in both directions. However, keep in mind that the hacksaw blade is designed to cut in the direction of teeth pointing towards the workpiece.
If you apply pressure during the reverse stroke, excess heat will be caused by friction and may damage/break the blade.
Junior Hacksaw Blade Direction
Generally, junior hacksaws with 6-inch blades also should be installed with teeth pointing down and forward towards the workpiece.
Some junior hacksaws are made with a simple metal-wire frame with no thumb wheel to tighten the blade. In this type of hacksaw, the frame may get compressed during heavy-duty cutting and the blade may slip out of the retainer pins. In such cases, installing the blade in reverse and opting for pull cutting may yield a better result.
Hacksaw Blade Installation
Hacksaw blade installation is a simple process once you know how to do it. The most important part is to ensure that the blade faces the right direction. This process may change depending on the hacksaw model you’re using. Here’s one method that should cover most models.
How to Replace Hacksaw Blade Step-by-Step Guide
First, it’s essential to understand the parts of a hacksaw. The D-shaped frame holds the blade in tension. The blade is attached to this frame using a wing nut and metal bar on one end and pins on the other end.
Remove the Blade
- Loosen the wing nut. This is the portion holding the blade in tension. Typically, this means turning the wing nut in the anti-clockwise direction. Doing this decreases the tension in the blade.
- Once the blade is adequately loosened, unhook it from the pins.
Install the Blade
- Check that the wingnut is loosened.
- Place the blade in the frame, hooking the blade into the pins on the frame.
- Ensure that the teeth are pointing down and away from the handle.
- Tighten the wing nut by turning it in the clockwise direction. This will pull the metal bar, increasing the tension on the blade. Do this until the blade is adequately tensioned.
How Tight Should the Blade Be?
The blade should receive enough tension to remain in place while cutting, but not so much that it snaps.
Loose blades will move around on the pins meant to keep them in place. In severe cases, the blade could even come off the frame. Loose blades are also hard to control, making for inaccurate, messy cuts.
Blades that are overtightened could snap, injuring the operator or damaging the workpiece.
A good rule to uphold is that the blade should not be able to move on the pins but should be able to flex slightly in the center when pushed with your finger. You can also test the blade tension by making a test cut. For this, clamp a scrap piece of material into a vice. The material should match the workpiece you aim to cut. Make a cut on this scrap piece. If the blade flexes or bends during the cut, it’s not tight enough, and you should further tighten the wing nut.
SET of Teeth on Hacksaw Blades
The setting of the teeth on a saw blade refers to how the cutting teeth are arranged. The teeth are typically not aligned along a straight line but bent slightly to the left or right, which is how a hacksaw blade can cut a groove slightly wider than the blade’s thickness.
This zig-zag arrangement of cutting teeth also allows for better chip clearance and the blade to move freely inside the cut instead of getting stuck.
The teeth setting on a blade fall into three categories: wave setting, alternate setting, and raker set.
1. Wave Setting
In the wave pattern set, the configuration of cutting mimics a wave. Here, a few teeth are set towards the right gradually, followed by a few teeth set to the left. This pattern is repeated along the length of the blade.
The wave setting is typically used for fine and superfine blades to cut hard materials.
2. Alternate SET
Here, the alternate teeth are bent in opposite directions to the entire length of the blade. This means one tooth is pushed towards the left and the next is pushed towards the right.
This type of arrangement works best for coarse blades with large teeth (low TPI).
Double Alternate
This is a variation of the alternate teeth setting, where two consecutive teeth are pushed in the same direction and the next two teeth are pushed in the opposite direction.
3. RAKER Setting
In a raker tooth blade, the first two teeth are pushed in the opposite directions while the third tooth is arranged straight. That means the cutting teeth are bent to the left, right, and straight and the pattern continues.
The advantage of RAKER setting is that they offer a better finish than the alternate set, yet cuts faster. They are also useful when cutting plastic and metals such as cast-ion that produce broken chips.
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