Expertise · Know-how

Band saw know-how: every step in the filing room

A band saw blade works under high tension, heat and vibration. How well it cuts and how long it lasts is decided in the filing room. Here we explain every step, from welding to final inspection, with tips from more than 80 years of practice.

The process

From band steel to a ready-to-cut blade

  1. 01Welding
  2. 02Levelling and tensioning
  3. 03Swaging and shaping
  4. 04Stellite tipping
  5. 05Profile grinding
  6. 06Side grinding
  7. 07Measuring and inspection

Not every blade goes through every step in every cycle. Welding is done once or for repairs, stellite tipping only for stellite-tipped blades. Levelling, grinding and inspection belong to every cycle.

01WeldingBand steel is turned into an endless saw band. The weld is the most sensitive point of the whole blade.

Why it matters

A poorly welded or untreated weld becomes hard and brittle. It is the first place to crack under constant bending over the wheels.

Practical tip

Never place the weld in a tooth, but in the gullet or tooth back. After welding, always check the weld area separately for flatness.

How it works

  1. Cut the band ends square and clamp them in perfect alignment
  2. Weld using a shielding gas process (MIG or TIG)
  3. Anneal the weld in a controlled way so the structure stays tough
  4. Grind the weld flat on both sides to equal thickness
  5. Then level and tension the area like the rest of the blade

Matching ISELI solutions

02Levelling and tensioningLevelling makes the blade flat, tensioning gives it the pre-stress for a stable, straight run.

Why it matters

In use, bumps, a distorted back and uneven tension across the width develop. A blade that is only ground loses running stability and cutting accuracy.

Practical tip

The right tension depends on wheel diameter, blade thickness, wood species and feed. A CNC levelling centre measures continuously and delivers reproducible, documented values, independent of the operator.

How it works

  1. Levelling: remove bumps and unevenness with rollers
  2. Tensioning: create a defined pre-stress by rolling the centre of the blade
  3. Back straightening: give the blade back a slightly convex shape
  4. Measure tension and back crown along the full blade length

Matching ISELI solutions

03Swaging and shapingSwaging widens the tooth tip, shaping brings it to exactly the same width and form.

Why it matters

The widened tooth tip cuts a kerf that is wider than the blade. The blade does not bind, and both sides of the tooth cut evenly.

Practical tip

Unevenly swaged teeth are one of the most common causes of washboard surfaces. Frozen or very hard wood usually calls for less swage than soft, wet wood.

How it works

  1. Cold-form the tooth tip with a swage anvil
  2. Match the swage width to wood species, moisture and blade thickness
  3. Shape the tooth evenly on both sides with shaping jaws
  4. Form the side clearance angle (typically 5° or 7°)
  5. Check width and symmetry of every tooth

Matching ISELI solutions

04Stellite tippingA wear-resistant cobalt alloy (stellite) is welded onto each tooth tip and then ground to shape.

Why it matters

Stellite is much harder and more wear-resistant than blade steel. The service life between two sharpenings increases markedly, especially with abrasive, hard or frozen wood.

Practical tip

CBN grinding wheels are the first choice for stellite-tipped teeth: they stay dimensionally stable and generate less heat than conventional wheels.

How it works

  1. Clean and position the tooth tip precisely
  2. Apply stellite by plasma or resistance welding
  3. Use round, trapezoid, shaped or wire stellite depending on the application
  4. Then grind the stellite tip to shape at face, top and sides

Matching ISELI solutions

05Profile grindingProfile grinding gives every tooth its geometry: tooth face, tooth top and gullet in one pass.

Why it matters

The tooth shape determines how the blade cuts, how it removes chips and how long it stays sharp. A cleanly ground, round gullet also protects against cracks.

Practical tip

A gullet with burn marks or a sharp edge is the starting point of most cracks. Several fine passes are better than one heavy pass.

How it works

  1. Define tooth shape, pitch, hook angle and clearance angle
  2. Probe the tooth profile automatically and set up the grinding wheel
  3. Grind face, top and gullet in one pass
  4. Keep stock removal low and cool sufficiently to avoid overheating

Matching ISELI solutions

06Side grindingAfter swaging or stellite tipping, the tooth sides are ground and brought to exactly the same kerf width.

Why it matters

Even sides with a defined clearance angle ensure a smooth cut surface, a straight run and a narrow, controlled kerf.

Practical tip

A smaller side angle gives a more stable edge and more sharpening cycles, a larger one more side clearance. The right choice depends on wood species and cut quality.

How it works

  1. Define side clearance at face and top (typically 0–7°)
  2. Grind both sides of the tooth symmetrically
  3. Check the kerf width across all teeth

Matching ISELI solutions

07Measuring and inspectionAt the end of every cycle, tension, flatness, kerf width and tooth shape are checked.

Why it matters

Only what is measured is reproducible. Documented values reveal faults early and make it easier to find the cause when a problem occurs in the sawmill.

Practical tip

Retire blades with gullet cracks in time. A blade breaking in operation costs more than a new one.

How it works

  1. Measure tension and back crown along the blade
  2. Check kerf width and tooth symmetry
  3. Inspect the gullets for cracks
  4. Record values for each blade

Matching ISELI solutions

Typical faults

From symptom to cause

Most problems show up in the cut or on the blade. The cause is often one step earlier, in the filing room.

Blade wanders in the cut

Possible causesToo little or uneven tension, uneven tooth heights, dull teeth

Action in the filing roomCheck and correct tension, even out tooth heights, resharpen

Washboard surface

Possible causesUneven pitch or kerf width, vibration, excessive feed

Action in the filing roomGrind the profile cleanly, check swaging and shaping

Cracks in the gullet

Possible causesSharp-edged or overheated gullet, excessive tension, small wheel diameter

Action in the filing roomGrind the gullet round and cool, reduce tension, retire the blade in time

Blade runs off the wheel

Possible causesWrong back crown, distorted blade

Action in the filing roomStraighten the back, level the blade again

Crack at the weld

Possible causesWeld not or incorrectly annealed, thickness difference in the weld area

Action in the filing roomAnneal correctly, grind flat, level the weld area

Burn marks, discoloured teeth

Possible causesExcessive stock removal, worn or wrong grinding wheel, insufficient cooling

Action in the filing roomUse a CBN wheel, reduce infeed, check coolant

Tooth corners break off

Possible causesClearance angle too large, hard knots, foreign objects

Action in the filing roomAdjust angles, stellite-tip the teeth for higher durability

Short service life

Possible causesUnsuitable tooth geometry, uneven swaging, grinding errors

Action in the filing roomMatch geometry to the wood species, automate the process steps

Your filing room, our know-how

Want to automate a step or facing a problem not listed here? Send us a photo of the blade or the cut surface.

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