Prolonging bandsaw blade life is an obvious topic of discussion, but there are ways to avoid such occurrences as weld breakage, premature blade dulling, and blade bounce from cropping up to affect work production, output, and cost.
When such instances occur, a few questions to ask include: was the blade tension set properly, was the correct blade used for the size and type of material being cut, and/or, was the proper break-in procedure followed prior to cutting?
The blame may lean toward low blade quality, but more often it is due to improper use.
Before operating a machine, it is important to follow procedure, especially if the idea of having purchased a blade for any cutting job is to achieve optimum blade life and avoid blade problems down the line.
Weld breakage is generally thought of as a manufacturer problem, but there are many instances where the problem may be avoided with a simple adjustment to your bandsaw. Although cases are unique, the following list of problems are the most common.
- Tension too high
- Wheel diameter too small
- Blade rubbing against wheel flange
- Guides worn or frozen
- Feed rate too heavy
- Chips stuck in guides
- Feed system not working correctly
- Internal stress pinching blade
To help determine if the saw blade broke at the weld and not at the back or the body of the blade, inspect the sides at the fracture to see if there are any grind marks at the weld’s finishing process. Poor blade weld suggests re-welding or replacement of the blade. If the blade’s tension is too tight, check the tension and adjust as needed. Tension valve wear on a bandsaw machine with hydraulic tensioning would mean checking the tension valve for a slow leak: the cause for an increase in pressure. Crooked welds mean that the blade ends might be mismatched at the weld and should also be welded straight, to a maximum of 0.15” hollow on the cutting edge using an 18” straight edge as a guide
Premature Dulling of Blade Teeth
- Blade teeth inverted (backwards)
- Improper break-in period
- Hard spots in material (like scale)
- Material work hardened (check for hardness and adjust feed)
- Improper cutting fluid or mixture
- Speed and feed too high
Improper break in might be to blame for the premature dulling of saw blade teeth. Always follow proper break-in guidelines. If the saw blade speed is set too fast, it will cause overheating of the cutting edge, so a decrease in speed is advised. Poor coolant flow, coolant type, or mixture will dull blade teeth, so checking coolant hoses and levels prior to machine use is a good idea. Too many teeth in the cut or no chip clearance, causing the blade to stop cutting and for the material to work harden is another dulling culprit. Make sure to compute for optimum teeth and use the correct tooth pitch. Replacing worn chip brushes will also help to prevent a dull blade.
Blade Bounce
Often a blade will bounce or jump when passing through the saw’s guides. This will cause problems by overloading the blade gullet, or causing expensive damage to the head feed system. The following is a list of the most common causes for a bouncing blade.
- Straightness of the blade
- Straightness of the weld
- Blade tension is set too low
- Wheels are out of round
- Blade guides are damaged
- Blade is bent
- Wheel Bearings are bad
Too many teeth in a cut will cause the gullets to fill up and the head to bounce, especially with small machines. Using a coarse tooth pitch will help. Missing teeth will cause blade bounce, so check the saw blade prior to use and replace the blade if necessary. Feed pressure that is too light, preventing the teeth from penetrating the work piece might mean needing to increase the feed pressure or decrease the blade speed in order to increase tooth penetration.
Allowing for time to implement preventive measures prior to starting any job is never a bad idea. This helpful guide should make that task a little easier while also saving time and expense as well as helping to prolong the life of your bandsaw blade.
