Understanding Bandsaw Blades
Bandsaw blades are a consumable item, and are one of the operating expenses involved in running an insulation fabrication shop or other shop using a bandsaw. Educated selection and use of bandsaw blades can greatly reduce a shop’s monthly blade expense.
Educated industrial bandsaw owners must first understand the distinction between the bandsaw and the bandsaw blade. The bandsaw blade is what actually makes a cut in the workpiece, or item to be cut. Typical bandsaw blades have hooked teeth which cut material away from the workpiece. Other styles of blade include grit edge and slicing, or knife edge, types of blades. The bandsaw is the machine which carries the blade. It includes the wheels and motor for turning the blade, and a table or other fixture for positioning the workpiece and moving it into the blade.
How to Use A Bandsaw
Different materials are cut most effectively and economically with different blades. There are many different styles and sizes of blade available to suit whatever material you may be cutting. So, when setting up to cut a workpiece, the first choice which must be made is what size and style of blade to use. Bandsawing machines must be designed to work with different styles of blades and types of workpieces. For example, the blades to cut large steel shapes and mineral wool batting are very different, so the bandsawing machines are also very different. Once you have chosen a blade to cut your material, you must choose a machine to carry the blade and support your workpiece. Most people are familiar with the “hook tooth” style blade. When a hook tooth style blade passes through the workpiece material, each tooth removes a bit of material. The result is a gap in the material where the blade has passed. This gap is called the kerf. Blades that work by leaving a kerf are called “cutting” style blades. These blades typically produce dust. A different style of blade is the knife edge, or “slicing” blade. As the name suggests, these blades part the material by slicing through the material without removing material. These blades work only on flexible materials such as soft foam. All this may sound very complicated, but Forrest Mfg. Co. has already done most of the work for you. Forrest has years of experience building saws and providing saw blades for a variety of customers. Based on that experience, Forrest has chosen the correct blades and designed the best machines for cutting insulation and other low and medium density materials. The following styles and sizes of blades are the best and most economical for cutting common insulation materials: If you are cutting a different type of material please contact Forrest Mfg. Co. and we will be glad to help you select a blade and bandsaw best suited to your application.
Bandsaw Blade Types
Carbon Steel, ½ inch wide 3 tooth per inch (TPI): Also available 3/8 inch wide. This is the standard, inexpensive “do-all” cutting blade of the insulation industry. This blade will cut all types of insulation materials. It is best suited to softer materials, such as urethane or phenolic foam, mineral wool, fiberglass batting, calcium silicate and similar materials. It will also cut cellular glass materials, but the teeth will quickly wear away, requiring very frequent blade replacement. All Forrest saws are shipped standard with one blade of this type.
Carbide Tipped, ½ inch wide 3 TPI: Also available 3/8 inch wide. This is a premium cutting blade meant for highly abrasive materials such as cellular glass. The outward appearance is very similar to the carbon steel blades, but the tip of each tooth is made of a near diamond hard carbide material. This material is much more expensive than the carbon steel blades, but many shops find that the superior longevity of this blade when used to cut cellular glass makes it economically superior. Forrest Mfg. Co. sells a specially developed carbide toothed blade designed to work with the Model 103 when cutting small radius pipe covering segments. Carbide tipped blades will also cut other, softer insulation materials, but blades have a finite life regardless of the material being cut, and it could be considered a waste of money to use an expensive blade when it is not required.
Carbide Grit Edge: This is a very expensive, specialty blade used only for cutting cellular glass. It cuts through the cellular glass very quickly and is extremely wear resistant. Few shops use this material because of the cost and the delicate handling requirements. When used properly, by a well trained fabrication crew, this can be the most economical blade.
All blades are available from Forrest either as welded to length, ready to use blades, or in bulk stock delivered in coils. Shops that purchase bulk blade must have a blade welder and employees trained in the use of the blade welder. Most smaller shops prefer to purchase welded, ready to use blades. Larger shops will purchase bulk blade and weld it themselves. Shops that own a blade welder will also reuse broken blades by welding the still useable pieces of several blades into complete blades. Forrest carries a large stock of the these and many other styles of blades. How long a blade lasts can vary greatly with the type of material cut, operator care, saw condition, and luck. As described above, different insulations materials will wear blades differently. A carbon steel blade may last a week or more when cutting phenolic foam, but only a few hours when cutting cellular glass. Operator care is potentially the most influential determinant of blade life. When cutting on a bandsaw, the material should be fed into the blade firmly, but only as fast as the blade will cut the material. Excess force on the workpiece and blade will shorten the life of the blade. Keeping the saw in good condition is also essential for good blade life. Blade wheels that are excessively worn or out of alignment, rough running bearings, or poorly adjusted blade guides will all reduce the useful life of a blade. There are a few tricks for increasing blade life. First, use high quality blades with a properly aligned, annealed, and smooth ground weld. Keep the saw, particularly the blade wheels and guides in good condition and alignment. Do not leave the saw running when not in use. A saw that is left running, but not cutting will break the blade in only a few hours. Keep the blade at an appropriate tension as described in the operator’s manual. Running the blade either too loose or too tight will shorten the blade life. De-tension the blade when it will not be used for more than a couple of hours. Leaving the blade tensioned when the saw is not used will shorten blade life, damage the rubber on the blade wheels, and shorten your bearing life. Blade wheels occasionally require resurfacing. As new, the wheels have a gentle crown or curve across the rubber (the same way bicycle tires have a curved cross section). The blade will always try to climb to the top of this crown. This tendency of the blade to seek the top of the crown is the only force keeping the blade on the wheels. If the rubber develops a flat spot on top of the crown the blade will not “know where to go” and will wander on the wheel, affecting the safety and quality of operation of the saw. Replace or resurface wheels with a flat spot on the wheel crown.
The bearings supporting the blade wheel shaft must be kept in good condition. Bearings that are worn will run rough or prevent proper alignment of the blade wheels. Check the bearings with the blade removed from the saw. First spin each wheel by hand and feel for any roughness. The wheels should turn very smoothly. Next grasp the blade wheel firmly and try to pull it out towards you, and move it up and down or side to side. If there is any movement of the blade wheel and shaft in the bearings the bearings are bad and must be replaced. The final choice of which blade to use, and estimated usage, is typically determined by the shop foreman. When setting up a new shop with an inexperienced staff, it is probably a good idea to use the inexpensive carbon steel blade, even for cutting cellular glass. Until the saw operators get a feel for the equipment and how to use it, they are likely to break blades much more frequently than normal. If you are cutting cellular glass, you can switch to carbide blades when your operators become more skillful with the equipment.
The Forrest radius cutting saws, the Model 103 and the Model 106, require the very careful blade selection. When cutting small radii insulation pieces, about 6 inch diameter or less, you need to use either a 3/8” blade or our special large kerf ½” carbide blade. Otherwise the blade will drag in the cut, creating barrel shaped insulation segments. For cutting larger diameters, use any of our ½ inch wide blades.
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