Bandsaw blade tension can be applied manually or automatically and is set on new machines by the manufacturer. Manual tension can be applied by spring or spring washers and in the field adjusted to an indicator for proper tensioning. However, over a period of time the washers and/or springs collapse and the tendency is to over tighten the blade, resulting in premature blade breakage. If this occurs, it is recommended to contact the machine manufacturer for replacement parts and correct settings for the tension. Automatic tensioning is applied through a pneumatic cylinder (air over oil) to a pre-determined amount of stretch or tightening which can be read off a dial indicator. Normally, this means of tensioning is very consistent. However, it can be affected by low air pressure or water in the air system.

 

Signs that you are over tensioning your blade could include:

  • Hairline cracks develop in the gullet of toothed blades.
  • Hairline cracks develop on the back edge of the blade.
  • The blade breaks in the weld or anneal area.
  • Premature blade breakage due to metal fatigue.

 

Signs that you are under tensioning the blade could include:

  • The blade is not cutting straight.
  • The blade is leaving marks or shadows on the material being cut.

 

Consistent blade tension can mean the difference between good blade life and poor blade life. (Find a full article on blade life here.) Simmons’ blades, depending on the width and thickness, are made to withstand a blade tension range of 16,000PSI – 21,000PSI. To make sure you are getting consistent tension readings, you should measure the tension during each installation of a new blade on each band saw. Simmons’ tension meter will help you ensure you are running your blade at the correct tension.

 

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