Comprehensive Guide: Bandsaw Blade Sharpening for Hardwood Cutting on Portable Sawmills in Australia

• Old Talgai PTY LTD

Bandsaw blades play a crucial role in achieving precise cuts and efficient performance in the timber industry, especially on portable sawmills. As hardwood is a commonly processed material in Australian portable sawmills, maintaining sharp bandsaw blades is essential for optimal cutting results. In this tutorial, tailored specifically for Woodland Mills™ Automatic Bandsaw blade sharpener available in Australia, we will guide you through the process of bandsaw blade sharpening, covering the key steps from blade inspect, setting the hook angle to completing the sharpening procedure and everything in between.

PPE

Please ensure that you always wear the appropriate PPE when working with Bandsaw blades and sharpeners.

MAINTENANCE

Portable timbermill bandsaw blades should be set and sharpened regularly for optimal performance. During normal sawing of most wood species this should be done at intervals of approximately 2 hours of effective cutting time (effective cutting time refers to the time the bandsaw blade was actually cutting). The bandsaw blade should be sharpened more frequently when cutting those species of wood with a high sand/ silica content or with common hardwood timbers found in Australian forest.

CLEANING AND INSPECTION

Clean sawdust and any coating from the bandsaw blade. Check whether there are cracks in the gullets (FIG 1). Small cracks can be ground away when sharpening the blade. If the cracks are so large that they cannot be ground away, the bandsaw blade should be discarded. Cracks in the gullet’s “G” are the most common cause of bandsaw blade breakage.

SAW BLADE GEOMETRY

Saw blade tooth geometry follows a particular “set” pattern where one tooth is straight (rake tooth), the next is set up, the next is set down, and then a straight rake tooth again. This 4-tooth pattern repeats throughout the entire length of the saw blade. The example below is illustrative of a typical Woodland Mills™ saw blade.

Pitch: The distance between the tips of two adjacent teeth.

TPI: The number of Teeth Per Inch on a blade, commonly referred to as Pitch. See definition above.

Gullet: The valley between the points of two adjacent teeth.

Gullet Depth: The distance measured from the gullet’s lowest point to the tooth tip.

Rake Angle: Also called Rake or Hook Angle, is the angle of the front face of the tooth perpendicular to the length of the blade.

Back Angle: Also called Relief Angle, is the angle down the back side of the tooth.

Rake Tooth: A straight tooth with no set.

Width: The thickness of the blade material without regard to set.

Set: The degree to which the teeth are bent up or down away from the blade.

Kerf: The narrow channel in the wood left behind by the saw, roughly equating to the distance measured across two opposing set teeth

SHARPENING GUIDELINES

The more accurate the sharpening, the straighter and smoother the bandsaw blade runs when cutting the log.

GULLET RADII

The radius in the gullet area “R” (FIG 2) should be 0.04 to ⅛ in [1 to 3 mm]. A radius under 0.04 in [1 mm] increases the risk of cracking. A radius over ⅛ in [3 mm] means that the chips are not broken.

BACK AND HOOK ANGLES

The back angle is normally between 10-12° (FIG 3) and the hook angle “A” (FIG 4) varies depending on the species of wood as shown in the table below:

PROFILING THE GRINDING DISC

The grinding disc must have the correct profile prior to sharpening a blade. Use the grinding disc profile template and whetstone shown in the table below to shape the disc.

**Note: do not shape the grinding disc using the profiling template. The profiling template is only used to check the disc profile after it has been shaped using the whetstone.**

The sharpener ships with a new grinding disc with a square profile. This and any replacement discs will require profiling before sharpening a blade.

**The profiling template should only be used as a guide. Tooth profiles from different blade manufacturers can vary and, therefore, custom grinding disc profiles may need to be made.**

OPERATION

1. SETTING THE HOOK ANGLE

Loosen the large knob on the back of the control box and rotate the grinding head to set the appropriate hook angle for the blade to be sharpened. Once set, tighten the locking knob.

Note that the grinding head can be set to custom angles other than the three (3) predefined angles shown. Simply rotate the head as desired and lock it in place with the knob.

2. INSTALLING THE BLADE

A. BLADE SUPPORTS

First, seat the far side of the blade into the notches on each of the blade supports.

Note: adjust the position of both the outer support arms to suit the blade length if necessary. The blade should ride against the bearings at the end of the each blade support. See section, ADJUSTABLE OUTER SUPPORT ARMS, for more information.

B. BACK REST

Position the near side of the blade so it slides down between the back rest and large washers.

C. GUIDE PLATE

Tighten the knob on the guide plate until it bottoms out. The blade should slide left-but not move in or out (forwards or backwards).

3. CALIBRATING THE ADVANCEMENT

A. CONNECT THE BATTERY

Before connecting the battery ensure both toggle switches are set to STOP. Follow the battery polarity label on top of the control box: connect the POSITIVE clamp (+ red) to the positive battery terminal and the NEGATIVE clamp (— black) to the negative battery terminal.

B. ADVANCE THE BLADE

Turn the advancer control on and allow the advancer to move the blade by two (2) teeth.

Turn off the toggle switch once the advancer has pushed the second tooth’s hook face as far to the left as it will go, and the lever is at its highest position.

**Listen to the gear motor as the blade advances. If it gets loud and sounds like it is straining, the blade is too tight. Adjust the jam nut behind the guide plate knob.**

C. ROTATE THE GRINDING HEAD DOWN

Manually rotate the grinding head down—do not turn it on. Seat the acorn nut at the end of the depth adjustment rod into the hole in the stop plate.

Turn the advancer on and observe the movement of the grinding disc relative to the tooth profile. Do not turn the grinding head on.

**Keep a free hand on the motor housing and be ready to lift the grinding head on the chance the grinding disc hits the blade.**

D. FINE-TUNE THE ADVANCEMENT

One half of the adjustment setting is fine-tuning the advancement so that the left face of the grinding disc is flush with the hook face of the tooth. Use the advancer knob to adjust how far the blade is pushed to the left. Turning it clockwise will push the blade farther to the left while counterclockwise will back off the advancer and reduce the blade’s leftward movement.

**Setting up a blade for sharpening requires a combination of both the advancement adjustment and the grinding head movement steps. Read and understand both sections before starting to fine-tune the sharpener.**

E. FINE-TUNE THE GRINDING HEAD MOVEMENT

The other half of the adjustment setting is fine-tuning the grinding head height so that the bottom of the grinding disc touches the bottom of the tooth gullet.

Loosen the lower lock knob counterclockwise so the depth adjustment rod can move freely. This knob simply acts as a locking mechanism for the rod once the proper depth has been set.

Turn the upper knob to adjust the depth of the grinding head. Clockwise raises the head; counterclockwise lowers it. Tighten the lock knob once the depth has been set.

**Setting up a blade for sharpening requires a combination of both the advancement adjustment and the grinding head movement steps. Read and understand both sections before starting to fine-tune the sharpener.**

As the disc leaves the gullet it should completely clear the next tooth’s back angle profile.

If the blade tooth profile has a steep back angle, adjust the position of the stop plate by flipping up the lever and loosening the M5 socket head cap screw and lock nut. This adjustment will allow the grinding disc to clear the tooth as it exits the gullet.

Retighten the cap screw and lock nut after moving the stop plate.

4. SHARPENING

With the machine now setup for the blade to be sharpened, follow the steps below to begin sharpening the teeth.

A. ADVANCE THE BLADE

Lift the grind head and while holding the advancer up, manually pull the blade back through until the weld seam is right of the grinding disc. Turn on the advancer toggle switch, advance the blade through until the weld seam is just left of the grinding disc, and then turn the switch off.

B. SET GRIND DEPTH

Rotate the grinding head down and seat the acorn nut in the stop plate hole. Turn on both the advancer and grinder toggle switches.

Make small adjustments to the advancer and depth adjustment rod to achieve a light grinding sound where approximately 0.004-0.008 in [0.1-0.2 mm] is being removed.

C. POSITION THE AUTO-STOP

Attach the auto-stop to the blade to automatically stop the sharpener once all the teeth have been ground.

It is important to correctly position the auto-stop in order to stop the sharpener before the blade weld seam reaches the grinding head. See “Auto-Stop Activated” graphic on next page.

Once the sharpener has ground 6-10 teeth (the number of teeth is dependent on the blade pitch), set the auto-stop on the closest blade tooth approximately 7 in [178 mm] right of the weld seam (e.g., 8 teeth from the weld on ⅞ in [22 mm] pitch blades).

When the auto-stop is positioned correctly it triggers the toggle switches just before the blade weld seam reaches the grinding disc.

The last tooth can be ground manually by moving the blade and lowering the grinding head by hand to sharpen the hook face.

The Woodland Mills™ bandsaw blade sharpener is a fully automated device designed for unattended sharpening of bandsaw blades. It operates on 12V DC, making it suitable for use in remote areas by way of a 12V battery. As the blade sharpens, the feeder arm automatically moves the blade forward, while the actuated grinding disc, operated by a cam, sharpens the face and gullet of each tooth. An automatic stop will turn the machine off once all teeth have been sharpened.

This sharpener can be adjusted for tooth rake angles of 7, 10, and 14 degrees. Additionally, the gullet depth and take-off can be adjusted, allowing 1.25″ – 1.5″ (31mm – 38mm) wide blades with tooth spacing (pitch) of 3/4″ – 1.25″ (19mm – 31mm) to fit.

If you own a portable sawmill invest in the Woodland Mills™ Automatic bandsaw blade sharpener to enhance the efficiency and productivity of your portable sawmill operations in your Australian forest. Experience precise cuts, reduced downtime, and maximize the lifespan of your bandsaw blades. Get Yours HERE!