Starrett Band Saw Blades: Troubleshooting And Cutting Speed Guide

starrett-band-saw-blades

Understanding how to troubleshoot some typical band sawing challenges can be helpful for new and experienced band saw operators alike. Although cutting issues will vary due to the material characteristics, size and shape, some general guidelines are a useful reference. In addition to the tips provided, it is recommended to consult your band saw machine and blade manufacturer for guidance in optimizing your sawing operations. Below are some common band saw blade challenges, their possible causes, and solutions.

Teeth StrippingTeeth-Stripping

  • Improper Blade Break-in - Improper break-in leads to chipped teeth which will shorten blade life as well as possibly lead to tooth strippage. Follow proper blade break-in procedure from the blade supplier.
  • Blade speed too slow - Blade speed should be established based on the type of material. If the speed is set too low, the teeth can over penetrate which will put excessive stress on them, eventually causing the teeth to strip. It is also important to refer to cutting recommendations from the saw machine manufacturer. 
  • Feed pressure too high - Reduce feed pressure to avoid over penetration and tooth strippage.
  • Tooth jammed in cut – When this occurs, do not enter a new blade in that cut. For example, when teeth strip there is a good chance that remnants of the teeth are left in the cut. If a new band saw blade is installed and then fed back into the same cut, it is likely that these remnants, which are as hard as the new teeth, will cause the new blade to strip teeth as well. Its always best to start a new cut or if you must cut at the same position, turn the material over and try coming in from the opposite side.
  • Poor cutting fluid application or ratio - Adjusting for proper coolant flow and ratio is key because cutting fluid is necessary on almost all materials. It provides both cooling and lubrication to the cutting surface. Without it, excessive heat is generated, leading to poor blade life and possible tooth strippage.
  • Hard material or heavy scale - Hard and scaley materials present their own problems. With proper feeds and speeds the challenges can be overcome, but these material types do tend to be more susceptible to strippage than other materials.
  • Wrong blade pitch - Using the wrong blade pitch, especially too coarse a band saw blade, will typically apply too much pressure to each tooth and eventually lead to strippage. Proper tooth selection is key.
  • Work moving in vise - Holding material tightly is a must, because any movement in bundled material or a single bar will cause tooth breakage. Tighten vises or use nesting clamps for best results.
  • Blade on machine backwards - Band saw blades may or may not be welded with the teeth going in the correct direction for your machine. It is imperative that the back of the blade be facing towards the band wheel flange and the teeth be moving in the correct direction when the machine is switched on. If it isn’t in the correct direction it is an easy fix - simply twist the blade inside out and re-install it.

Premature Dulling of TeethDull-Teeth

As is the case with Teeth Stripping, having the blade backwards on a machine, improperly breaking in the blade, working with hard or heavy surface scale material, having improper cutting fluid application or ratio, and running the speed or feed too high are all also challenges that may lead to the premature dulling of teeth. Refer to the previous section for solutions.

In addition, when cutting material that has a tendency to work harden, it is imperative that each tooth penetrates. If not, work hardening can occur and for all intents and purposes, the blade will only rub across the material, causing premature dulling. Increasing feed pressure is recommended if this occurs.

Wear on Back Edge of BladeWear-On-Back-Of-Blade

  • Excessive back-up guide preload - Properly adjusted back-up guides are crucial to good blade life. If positioned in such a way as to “push” the blades out of the guides, not only will the backup guides themselves wear out quickly, but the back of the blades will also be damaged.
  • Low Blade tension - Low blade tension will “bow” the blade as it travels between the guide arms. This flexibility will cause cracking in the back of the blade. Refer to operator’s manual for guidelines. 
  • Excessive feed rate or pressure - Reduce feed rate or pressure to avoid wear on the back edge of the blades and other issues. 
  • Damaged or worn back-up guides - Replace back-up guides when damaged or worn -Backup guides should be in good condition, as this is where the back of the blade rides when cutting. The guides should be smooth (without grooves or cracks) and adjusted properly.
  • Guide arms spaced too far apart - Similar to low tension, if the guide arms are too far apart, the blade will tend to bow. This leads to premature cracking. Adjust the guide arms closer to the work. 
  • Blade rubbing band wheel flanges - Adjust blade tracking. It is extremely important that the back of the blade does NOT ride on the band wheel flange. It should be adjusted as close as possible but should not hit the flange. If the blade rubs the flange, it will create a sharp edge on the back and cause breakage. 

Blade BreakageBlade-Breakage

Straight Break Indicates Fatigue

  • Band tension too high - Refer to operator’s manual and reduce band tension. Most production machines require between 28,000-32,000 psi of blade tension. This should always be checked with a blade tension gauge and kept within the manufacturer’s preferred range.
  • Wheel diameter too small for blade width - Use narrower blade because the blade will break if it is not supported properly, and it is usually not a straight break.
  • Worn or chipped guide - Replace worn or damaged guide to prevent a break, which will likely be uneven. A worn or chipped guide can cause a straight break, but typically gouges the back of the blade and causes crooked breaks.
  • Blade rubbing wheel flange or having side guides that are too tight will result in blade breakage. Proper adjustment is necessary.

Inaccurate CutInaccurate-Cut

  • Guide arms too far apart - Adjust guide arms closer to material.
  • Blade worn out - Replace the blade when it is at the end of its life cycle because it will typically dull out and no longer cut, or perhaps result in crooked cuts. Also, it is possible that the blade will break due to backer fatigue.
  • Excessive or inadequate feeding - Check cutting recommendations. Excessive feed rates can cause breakage in certain circumstances; however this is not typical.
  • Guides worn or loose - Tighten or replace guides. If guides are not adjusted properly, premature blade failure and possible breakage is possible. 

Band Leading in Cut Band-Leading

  • Over feeding - Check cutting recommendations. As noted previously, blade speed, feed pressure and feed rate are all required to be in balance for the particular material being cut. If any or all of these are not near recommended specifications, then crooked cutting will most likely result.
  • Low band tension - Refer to operator’s manual. Without adequate and proper blade tension, the beam strength will be insufficient to hold the blade straight, resulting in crooked cuts.
  • Tooth set damaged - Check material hardness. Damaged tooth sets can occur with both tracking issues as well as guide issues. If either of these issues are present, then damage to the set (side of the teeth) is very possible and will result in crooked cuts.
  • Guide arms loose or too far apart - Adjust guides and/or guide arms. Similar to low band tension, guides that are spread too far apart can cause crooked cuts because the blade is not supported well enough to keep cutting straight.

Chip WeldingChip-Welding

  • Worn, mis-adjusted or missing chip brush - Replace or adjust chip brush. While a chip brush is not technically responsible for chip welding, if a brush is not installed correctly or is inoperative, it can allow chips to load up in the gullets which can increase heat and lead to chip welding.
  • Improper or lack of coolant - Check coolant flow and fluid type. As stated previously, coolant is important for both cooling and lubricating. If it is mixed incorrectly or the wrong type of coolant (i.e. neither cooling or lubricating) is present, it can lead to excessive heat and chip welding.
  • Excessive feed or speed - Check cutting recommendations. Both of these factors can cause chip welding due to heat buildup.

Teeth FractureTeeth-Fracturing

Fractures on back of teeth indicate work moving in the vise

  • Material moved in vise - Inspect and adjust vise, and use nesting clamps. If the material being cut is not held tightly, and the material is allowed to spin or vibrate, tooth breakage (fracture) due to the material hitting the back of the band saw blade usually results.

Irregular BreakIrregular-Break

INdicates material movement

  • Indexing while blade in work - Adjust indexing sequence. It is imperative that the machine is indexing correctly. If not, it can push the material forward while either the blade is down or not high enough, breaking the teeth.
  • Saw head falls into work while neutral - Check hydraulic cylinder. Always make sure that the head on horizontal saw is not leaking down and the blade always clears the material. Horizontal saws have one or two hydraulic cylinders that control both the up and down motions. It is more typical than you might think for older saws to develop cylinder issues which cause the head to leak down and come in contact with the material, causing damage. 

Rough CutRough-Cut 

Washboard surface, vibration and/ or chatter

  • Dull or damaged teeth – Install new blade. Once teeth are damaged, their clearances and angles will be different, causing what will range from a mild washboard to a significant washboard cut.
  • Incorrect feed or speed - Refer to cutting recommendations. As noted previously, proper feeds and speeds are necessary not only for blade life and sawing production, but for also the surface quality of the piece being cut. Running a blade at too slow a speed will result in teeth with loaded chips, allowing the teeth to “walk”. Too fast a feed rate will also cause the teeth to load, producing a similar outcome.
  • Blade not supported properly - Adjust or tighten guide arms. Loose guide arms allow the blade to move back and forth, causing the blade to search for a straight cut.
  • Low blade tension - Refer to operator’s manual. Low blade tension allows the blade to “walk”. Tension should always be set to the machine manufacturer’s recommendations and a blade tension gauge should always be used.
  • Incorrect tooth pitch - Use proper tooth selection. Like incorrect feed and speed, an incorrect tooth pitch can lead to the gullets loading with chips, allowing the teeth to wander.

Wear Lines, Loss of SetWear-Lines

  • Blade riding up into saw guides. Check for worn or missing backup guides and adjust or replace as necessary. Wear lines or “grooves” are usually caused by bad side guides. Whether the guides are broken or worn, they can cut wear lines or grooves into the side of the blades. If a blade is riding up into the guides, this will typically indicate a bad or possibly missing backup guide. In this case, it can be so bad that the teeth ride up into the side guides, causing excessive wear and crooked cuts.
  • Side guides too tight - Adjust guides properly. Most side guides are zero clearance, meaning they should be up against the band saw blade in a snug manner. It is possible to over tighten, which will lead to wear on the side of the blades.
  • Teeth riding on band wheel surface. Adjust tracking or replace wheel.
    As noted above, tracking is very important for good blade life. When properly tracked, the back of the blade will ride close to the bandsaw wheel flange but not against it. In addition, the teeth should be off the wheel itself, so as to prevent the wheel from flattening the tooth set.
  • Wrong blade width for machine - Refer to operator’s manual.
  • Chips being carried back into the cut - Replace or adjust chip brush. Refer to previous comments about the chip brush. In this scenario, it is possible but unlikely to cause grooves in the blades.
  • Insufficient coolant flow - Adjust coolant flow. Without sufficient coolant, heat becomes a factor, and can lead to scoring of the band saw blade by the guides.

Twisted BladeTwisted-Blade

  • Blade binding in cut - Adjust feed or use heavy set blade. Blades binding in a cut is typically an issue with the material being sawn. Materials with high internal stresses will tend to pinch the blade as it travels through the material. The only solution to this is to either use a wedge of some sort, or move to a blade with a heavier set. This will allow for a wider kerf and give the blade more room before the material closes in on it.
  • Work loose in vise - Adjust vise. See previous comments about this challenge.
  • Guide arms spread too far apart - Adjust guide arms closer to material. Without proper blade tension, the band saw blade will bow and may twist, causing both breakage and crooked cuts.
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