Band saw blade care for band saws

⚙Care and inspection

• Break in the blade (break-in cutting)Band saw blade (new)

  Cut with a reduced feed only during the first cuts with a new blade, letting the tooth tips wear in gradually before raising to normal conditions. WIKUS says to use about 75% of the proper speed and about 50% of the feed and cut about 500 cm² (or about 15 minutes). Starrett says to use normal speed with 50% (soft materials) or 75% (hard materials) of the feed force. After break-in, return the speed first and raise the feed in steps (WIKUS)

  The cutting edge radius of a new tooth tip is very small, and cutting at full load right away chips the edge finely. Raising the load gradually puts a fine radius on the edge, so chips release more easily and the tooth tip is stronger (Starrett, WIKUS). DoALL also says skipping break-in makes the blade dull early and puts fine cracks in the tooth tips, shortening life. New blades tend to vibrate and make chatter noise. If there is noise, lower the saw speed until it stops (WIKUS). WIKUS says coated blades vibrate less and finish break-in sooner^{[1][2][3][4][5]}

  Source	Saw speed	Feed	Break-in amount
  WIKUS (bimetal, carbide)	About 75% of the proper value	About 50%	About 500 cm² or about 15 minutes (about 300 cm² for small material)
  Starrett (soft materials: carbon steel, aluminum)	Normal speed	50% of feed force	323–645 cm² (50–100 in²), then 100%
  Starrett (hard materials: stainless steel, tool steel, nickel-based alloys)	Normal speed	75% of feed force	161–484 cm² (25–75 in²), 100% at 323 cm² (50 in²)

• Check and adjust the tension with a tension gaugeBand saw blade, tensioning device

  Attach the tension gauge to an untensioned, straight blade, zero it, and read the scale while applying tension with the machine (Starrett's Model 682 procedure). To check a blade that is already tensioned, zero the gauge with the blade tensioned, then release the machine tension and read it. WIKUS says to seat the gauge as close to the tooth root as possible and measure twice, with the blade slack and tensioned

  Too little tension lets the blade wander in the kerf and cut crooked; too much breaks the blade (WIKUS). Starrett also says too little tension reduces cutting performance and too much leads to blade breakage. Starrett says to use the upper part of the range when the guide arm spacing is wide and the lower part when it is narrow. The values are guidelines from blade makers; the machine's operation manual comes first^[6][7][8][1]

  Source	Tension guideline
  WIKUS	250–300 N/mm² (usual recommendation)
  Starrett (bimetal, width 38 mm and over)	30,000–40,000 psi (2,100–2,800 kgf/cm², about 207–276 N/mm²)
  Starrett (bimetal, width up to 38 mm)	25,000–35,000 psi (1,800–2,500 kgf/cm², about 172–241 N/mm²)

• Choose the tooth pitch (teeth per inch) by the thickness being cut (cutting length)Choosing a band saw blade

  Pick the tooth count by the length over which the blade is in contact with the material (the diameter for round bar, the width of cut for square stock). Thinner sections get a finer pitch (more teeth); thicker sections get a coarser pitch (fewer teeth). Variable pitch (a blade whose tooth spacing changes along its length) reduces vibration and covers a wider range of sizes with one blade (WIKUS). When cutting a bundle, use a pitch one step coarser than recommended for a single piece (LENOX)

  A wrong pitch leads to chipped teeth if too fine and blade damage if too coarse (OSG). Too coarse puts too much load on each tooth and strips teeth; too fine packs chips into the gullets and strips teeth (Starrett). Tsune Seiki says the best condition is when 3 to 24 teeth are always in contact with the material, and measures the length as the diameter or one side for solid stock, 2 to 3 times the wall thickness for pipe, and the length of the longest cut surface for structural shapes. Starrett says the ranges in its table overlap, so choose the coarser pitch if cutting speed matters most and the finer pitch if cut surface quality matters most. For a quick lookup, see the "Tooth pitch quick reference" tables^{[9][7][10][11][12][13]}

• Choose blade width and thicknessChoosing a band saw blade

  On horizontal machines, use the blade width and thickness specified by the machine manufacturer. When cutting curves on a vertical machine (contour machine), choose the blade width from the smallest radius you want to cut (WIKUS, Starrett)

  A wider blade is more stable, and blade thickness affects stability and resistance to twisting, which in turn affect how straight the cut is (WIKUS). Tsune Seiki also says a thicker blade is stiffer, and a wider blade is stiffer still and cuts more accurately. For guideline blade widths and minimum cutting radii on vertical machines, see the "Minimum radius for contour cutting" table^[9][10][13]

• Match saw speed (m/min) and feed to the materialCutting conditions

  Set saw speed by the type and hardness of the material. The harder the material, the lower both speed and feed (Starrett). On a machine that cuts many materials, set the speed for the hardest material (DoALL)

  Too high a speed wears the teeth quickly from heat (DoALL). Too low a speed makes the teeth dig in too deeply and strains them, stripping teeth (Starrett). For example speeds by material, see the "Saw speed examples" table (LENOX bimetal blades). Daito Seiki gives the applicable saw speed of its M42 HSS DL blade as 20–120 m/min^{[11][14][15][16]}

• Set the guide arm position and the guide clearanceGuides

  Keep the guide arms as close to the material as possible (WIKUS, OSG). Mechanical side guide clearance is 0.02–0.05 mm; for hydraulic guides, check the clamping pressure (WIKUS). Run the blade so that 1–2 mm of the teeth and gullet stick out past the guides (WIKUS). Set the back-up guide so it does not push the blade back out (Starrett). Readjust the guide arms after mounting a new blade (Starrett)

  Loose or widely spaced guides let the blade wander and cut crooked. A misplaced guide, rollers set too tight, or a blade sitting too deep in the guides breaks the blade (WIKUS). OSG lists wear or tilt of the side rollers and inserts as a cause of crooked cuts and body cracks^{[17][8][14][18][19][20]}

• Adjust the chip brush and replace it when wornChip brush

  Set the brush so its bristle tips almost reach the deepest part of the gullet. With a variable pitch blade, set it to reach the shallowest gullet. Use a powered brush if possible. Do not use resin brushes containing abrasives (WIKUS)

  If chips are not cleared from the gullets, they pack in and build up heat, weld to the teeth, and strip them (Starrett). DoALL also calls the brush the "best ally in clearing chips" and recommends replacing it regularly when worn. OSG lists brush wear and poor brush position as causes of chipped teeth. WIKUS says that if the brush damages the teeth on one side, the blade cuts crooked^{[21][15][5][18][22]}

• Aim the cutting fluid at the tooth roots and keep the concentrationCutting fluid

  Set the nozzle where it cools the blade well, and if possible aim the fluid at the tooth roots from the front (WIKUS). Check the concentration with a refractometer and match it to the workpiece material (WIKUS)

  Too little cutting fluid wears the teeth quickly and welds chips to them, stripping teeth (WIKUS). DoALL says the tooth tip temperature can rise from about 20 °C (68 °F) at the start of the cut to about 700 °C (1300 °F) within a few cuts, which reduces hardness and shortens life, and also work-hardens the material. OSG lists improper cutting fluid amount or concentration as a cause of body breakage, and too little fluid and nozzle position as causes of chipped teeth^{[21][7][23][19][22]}

• Procedure for changing a bladeBlade change

  Turn the power off (HOZAN says to unplug the power cord). Remove chips from the wheels and guides, move the chip brush away from the blade, release the tension, and remove the old blade (Starrett). Put the new blade on the wheels with the tooth protector still on, run it through the guides, check the tooth direction, apply tension, and check the tension. Remove the protector, run the machine empty, set the brush at the same time, and break the blade in (WIKUS)

  Wrong tooth direction, too little tension, or forgetting to set the guides reduces blade life and cutting accuracy (Starrett, WIKUS). Wear gloves and safety glasses when handling blades (Starrett, HOZAN)^[18][8][24]

• Unpacking and handling a folded bladeBand saw blade (new)

  A folded blade is under tension and can spring open and injure you when the retainer is removed. Place it on the floor and hold it down while opening it (WIKUS). Do not throw the blade to open it (Starrett)

  Throwing or knocking the blade damages the teeth and reduces sharpness (Starrett). If the packaging is damaged, the blade may be damaged too, and a blade with kinks, cracks, or chipped teeth must not be used (WIKUS). WIKUS says blades up to 41 mm wide and 6,000 mm long are folded into round coils (1 or 3 turns), and larger ones into a figure 8 (pretzel shape)^[7][18]

• Store spare bladesBand saw blade (spare)

  Keep them in their packaging in a dry, cool place and take them out just before use. Do not stack bimetal, carbide, or diamond blades without tooth protection (WIKUS)

  Moisture makes them rust (WIKUS). DoALL also recommends storing blades in a clean, dry place to prevent rust and damage. WIKUS says there is no limit on storage time if stored correctly. HOZAN also asks that the machine itself be stored away from heat, humidity, and dust^[7][5][24]

• Keep blade tracking and wheel condition goodWheels

  Bring the blade back as close to the wheel flange as possible, but do not let it touch (Starrett). If the blade back rides up on the flange, readjust tracking with the wheels and guides (WIKUS)

  Scratches on the wheel surface, tapered wear, bad bearings, and runout put uneven force on the blade and break it (WIKUS). DoALL also says neglecting wheel care leads to poor tracking, uneven wear, and breakage. Wheel resurfacing and replacement are done by manufacturer service^[17][14][5]

• If you find a twisted, kinked, or bent bladeBand saw blade

  Do not use a blade with kinks, cracks, or chipped teeth (WIKUS). Too little tension lets the blade flex between the guide arms and cracks the back, so check the tension with a tension gauge (Starrett)

  A damaged blade is a source of crooked cuts and breakage. OSG says that if the weld of a contour machine blade is not straight, the cut will run crooked. WIKUS shows in a video how to coil a blade when putting it away (replacement, end of life, change of material)^[7][14][25]

• Weld cracks and weld straightness (contour machine blades)Band saw blade (weld)

  When you weld coil stock into a blade yourself, check that the weld is straight. If the blade breaks at the weld soon after welding, or you cannot weld it straight, use a pre-welded blade (OSG)

  A poor weld cracks at the weld, and a weld that is not straight causes crooked cuts (OSG). For weld cracks, WIKUS lists redoing the weld and inspecting for hidden machine faults (guides, wheels). OSG says that if the cut is straight at the weld, suspect material selection, tension, or roller wear, and if it cuts at an angle, suspect pitch too coarse, descent speed, or machine vibration^[25][26][17](1 source, for reference)

• Judge when to replace the bladeBand saw blade

  Replace the blade when these signs appear: fine cracks in the blade back, worn, chipped, or stripped teeth, a wavy (washboard) cut surface, scuffing of the blade by the guides, a high-pitched or scraping sound (Starrett). When the cut surface or dimensions no longer meet requirements (WIKUS). Burning, chatter, cuts that are not square, longer cutting time (DoALL)

  Continuing to use a blade past its life damages the blade and material further with heat and reduces quality and safety (Starrett, DoALL). Fragments of teeth may remain in the kerf right after teeth are stripped, and a new blade in the same kerf will lose teeth too. Start the cut at a new position or turn the material over and cut from the other side (Starrett)^[14][7][5]

• Cutting bundles and structural shapesCutting conditions

  When cutting a bundle, use a pitch one step coarser than recommended for a single piece (LENOX). Clamp the material firmly; bundles of round bar roll easily, so tighten the vise or use a bundle clamp (Starrett)

  If bundled material shifts during the cut, teeth chip (Starrett). OSG also says that in bundle cutting, insufficient clamping makes the cut run crooked. Structural shapes subject the blade to shock and vibration every time it enters and leaves the material, so the blade wears faster than with solid stock (Starrett)^[11][14][20]

• Adjust the guard and roller guides on a small vertical machineSafety guard, roller guides

  Lower the safety guard to just above the material and lock it. After changing the blade, set the roller guides to the blade width and thickness so the left and right rollers just lightly touch the blade. Do not overtighten. Set the blade speed for the material using the speed control chart on the machine (example: scale 1–4 for iron, 1–6 for brass)

  A guard set too high is dangerous and also leads to blade breakage and a rough cut surface. Overtightened rollers hinder blade feed and make the rollers noisy (HOZAN). This is the example of the HOZAN K-100. The rated time is 30 minutes, and the machine must rest for as long as it was used^[24](1 source, for reference)

▦Tooth pitch quick reference (variable pitch bimetal blades, WIKUS)

Contact length is the length over which the blade is in contact with the material (the diameter for round bar, the width of cut for square stock). The ranges overlap, so at the boundaries choose by material and cutting method. WIKUS's table also has other variable pitch series (such as 2.5-3.4) and a constant pitch table. OSG's guideline is 4/6 for 50–90 mm, 3/4 for 80–150 mm, and 2/3 for 120–300 mm^[9][7][12](1 source, for reference)

▦Tooth pitch quick reference (size of cross section being cut, Starrett)

The mm values are converted from inches and rounded. The ranges overlap, so choose the coarser pitch if cutting speed matters most and the finer pitch if cut surface matters most (Starrett). For pipe and structural shapes there is a separate table, selected by the combination of outside diameter and wall thickness^[10](1 source, for reference)

▦Blade tension guideline

Starrett's table is "a guideline for average cutting conditions." Use the upper part of the range when the guide arm spacing is wide and the lower part when it is narrow. N/mm² values are converted as psi × 0.006895 and rounded. The machine's operation manual comes first^[6][7][1]

÷Converting tension units (N/mm², kgf/mm², kgf/cm², psi)

1. Check the units on the source or the tension gauge scale (N/mm², kgf/mm², kgf/cm², psi)
2. Convert to N/mm² (= MPa) with the factors below before comparing
3. Check that the value is within both the machine operation manual's specification and the blade maker's guideline

kgf/mm² → N/mm²

× 9.807

kgf/cm² → N/mm²

× 0.09807

psi → N/mm²

× 0.006895

N/mm² → psi

× 145.0

Worked example: Starrett's 30,000 psi

30,000 × 0.006895 ≈ 207 N/mm² (matches 2,100 kgf/cm² × 0.09807 ≈ 206 N/mm² in the same table)

Worked example: WIKUS's 250–300 N/mm²

× 145.0 ≒ 36,000〜44,000 psi、÷ 9.807 ≒ 25〜31 kgf/mm²

The factors follow from the definitions of the units. Starrett's tension gauge (Model 682) has both psi and kgf/cm² scales^[6][7]

▦Saw speed examples (bimetal blades, LENOX)

Extracted from the bimetal blade column of LENOX's speed chart (the same chart also has columns for carbide blades and others). It varies with blade type, maker, and material condition, so decide using the blade maker's recommendation and the machine's capability^[11](1 source, for reference)

÷How to find the break-in conditions and number of cuts

1. From the material and size, decide the normal saw speed and feed (see the saw speed examples table and the blade maker's recommendations)
2. Decide the break-in conditions. WIKUS: about 75% speed, about 50% feed. Starrett: normal speed, and 50% (soft material) or 75% (hard material) of the feed force
3. Find the area of one cut (round bar: π × D² ÷ 4; square stock: width × height)
4. Divide the break-in area by the area of one cut to get the number of cuts to use for break-in
5. When break-in is finished, slowly return the speed to normal and raise the feed in steps (WIKUS). Starrett also says to raise the feed over several cuts once the blade is fully in the material

Cross-sectional area of round bar (cm²)

3.14 × D² ÷ 4 (D in cm)

Number of break-in cuts

Break-in area (cm²) ÷ area of one cut (cm²), rounded up

Speed during break-in (WIKUS)

Normal speed × 0.75

Feed during break-in (WIKUS)

Normal feed × 0.5

Worked example: conditions

Carbon steel round bar, 50 mm diameter, normal saw speed 70 m/min (1045 in LENOX's chart)

Worked example: area of one cut

3.14 × 5.0² ÷ 4 ≒ 19.6 cm²

Worked example: WIKUS break-in

Speed 70 × 0.75 ≈ 53 m/min, feed halved, and 500 ÷ 19.6 ≈ 26 cuts

Worked example: Starrett break-in (soft material)

Keep speed at 70 m/min and use 50% of the feed force, 323–645 cm² → 17–33 cuts

WIKUS gives about 300 cm² for small material and about 15 minutes for large material as guidelines (100–300 cm² in its FAQ). The break-in amount varies among sources^{[1][21][4][3][11]}

▦Minimum radius for contour cutting and blade width (vertical machine, Starrett)

A guideline for cutting curves on a vertical machine. For straight cuts, use the blade width specified by the machine manufacturer^[10](1 source, for reference)