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Preventing Weld Breaks

There are ways to prolong bandsaw blade life and avoid weld breakage.

All bandsaw blades are welded or soldered. A strip of teeth are cut to length and welded to make a loop. Sometimes, the saw blade will break at this weld. A break is the result of an improper weld, or that there is too much tension on the bandsaw wheel, or even that a bad quality blade predisposed to such a break was purchased.

Weld breakage is common, and questions a vendor may ask include whether or not proper blade tension was applied, what size and type of material was being cut, and had the operator performed proper break in procedure prior to use.

If the saw blade isn’t breaking at the weld, it means there are other factors such as blade twist that will cause fatigue and early wear-out. It could also be an adjustment issue between the guide bearings and the guide.

Determine that the blade broke at or near the weld and not in back or on the blade body. Inspect the sides of the fracture to see if there are any grind marks from the welds finishing process.

If a poor blade weld is detected, it is possible to re-weld the blade or simply replace it with a new saw blade. If over tension is to blame, be sure to check tension and adjust as needed.

Common causes for bandsaw blade breakage at the weld include tension that is too high. Always reduce the bandsaw’s blade tension when not in use. Tension build-up while the machine is idle may cause the blade to bend, leading to fatigue and breakage.

On hydraulic tension bandsaws, tension valve wear and pressure are increased, so check the tension valve for a slow leak.

Other factors to take into consideration include:

  • too small wheel diameter
  • blade rubbing against wheel flange
  • guides worn or frozen in place
  • bad welding method
  • feed rate too heavy
  • metal failure
  • chips stuck in guides
  • feed system not working correctly
  • internal stress pinching blade

A properly adjusted and well-maintained bandsaw are ideal. Get to know the bandsaw and get it in good running condition.

If the saw blade rides too far back on the wheels and puts a lot of pressure on the bearings, breakage will occur.

When running without cutting, the bearings should not be spinning and there should be almost no space between the bearings and the back of the blade. The slightest push from a block of wood should press the blade back into the bearing.

The guide blocks should have an air gap on both sides of the blade the thickness of a piece of paper. The upper guide assembly should be anywhere from 1/4″ to 1/2″ above the work piece being cut. If too much blade shows, it becomes dangerous. Guides spaced too far from the block will cause the blade to wander and create a blade break situation.

Allow for time to incorporate preventive safety and full-function measures prior to starting any cutting process.

Hopefully, this guide will make that task a bit easier while also saving time and expense as well as to help prolong the life of any bandsaw blade.

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