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How do you know when your saw blade needs sharpening

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This was an email I received from the link below. I found it interesting and thought you might too.

Saw blade secrets: Achieve chip-free cuts, avoid dull blades
( July, 09 2009 )

Saw blade manufacturers share advice on achieving chip-free cuts in particleboard and MDF, as well as determining when a saw blade needs to be sharpened.

Q: What is the “rule of thumb” or best guideline for determining how often or when a saw blade needs to be sharpened?

A: Gene Veening, President, ROYCE//AYR Cutting Tools Inc.: For most users the evidence will be in the quality of the cut. On panel saws, chipping of the melamine finish will start to show and the machine amperage draw will increase; on manual machines, the material will be more difficult to push through the blade. It is of great importance that the blade is being sharpened as soon as visible deterioration occurs, since the blade will dull up much faster if the blade continues to be used, resulting in more of the tip having to be removed in order to get a new sharp edge, which results in a decline of overall blade life.

A: Joe DeCotiis, Operations Manager, Charles G. G. Schmidt & Co. Inc.: Some guidelines to determine when a blade should be sharpened: Know how long a blade can be used before the cut starts to deteriorate. Take it off before chipping or quality of cut goes down hill. Listen to the blade. A trained ear can tell from the sound of the machine when the blade is working harder from getting dull. A sharp blade requires less horsepower and cuts quieter than a dull blade. And at the first sign of chipping, remove the blade and replace it. These three suggestions will minimize rejecting material.

A: Miki Simpson, Eagle Outlet Store Manager, Eagle America: A dull blade feels like it is fighting thru the wood to cut. It will start to heat up and burn the wood. The heat causes gum and pitch buildup, which only increases the heat. Heat will shorten the life of your blade teeth. With a dull blade, your stock tends to climb over the blade, or you might feel the need for an increase in feed force. You should also watch for rounded edges and chipped teeth. If you are experiencing any of this with your blades, it is probably time to have them sharpened. The best “rule of thumb” is to make sure you do consistent, preventative blade maintenance to keep your blade sharper longer. Unless doing production work, a blade may last two to three years without sharpening if it is properly maintained. Clean them to reduce gum and pitch build up. Care in handling and storing your blades will prevent chipped teeth.

A: Joe Arnoldus, Vice President, AA Carbide: Resistance in the cut is a good indication. Fraying and chipping also are good indications of when to change to a sharp blade. How often would depend on how long it would take to see these indications.

A: Karin Deutschler, President, GUHDO USA Inc.: When the saw blade starts to dull, the amps on the saw motor will increase as the blade has to labor harder to cut through the material. This will be noticeable to the saw operator, as the blade will sound louder. The finish of the cut will begin to deteriorate as well. When the blade begins to dull it should be pulled and sharpened, and not “pushed” to its limit. Cutting with dull blades poses a risk of tips coming off and saw plate cracking due to overheating.

A: John Michel, Director of Sales and Technical Services, LEUCO Tool Corp.: Considerations for determining when to have a saw blade sharpened:

• Cutting quality – No longer acceptable

• Noise from the saw blade while cutting – Dull saws are louder than sharp ones

• Motor / amp draw – Dull saws require more power.

• Actual wear on the teeth – Visual inspections and blade cleaning are good disciplines.

In many cases saw blades are changed or sent out for sharpening when the cutting quality is no longer acceptable. In some applications this works fine, but in others it may not be the most cost effective method. An example may be when sawing raw particleboard. When a surface laminate is not present, the cut quality may appear acceptable even with a dull saw. Over-running a saw will require the sharpener to remove more carbide, taking away from the serviceable tool life.

Q: What are the top 3 “secrets” to achieving chip-free cuts in particleboard or MDF on a panel saw or sliding table saw?

A: Gene Veening, President, ROYCE//AYR Cutting Tools Inc.:

• Making sure you are using the right blade for the application, i.e. cutting raw board, cutting melamine-finished one or two side particleboard or MDF, cutting particleboard finished with wood veneer. All of these operations may require a different style of blade. One blade fits all just will not do.

• Making sure the blade is sharp and well adjusted to the scoring blade.

• Making sure the saw flanges are clean and burr free.

A: Joe DeCotiis, Operations Manager, Charles G. G. Schmidt & Co. Inc.: Three ways of achieving chip free cuts are:

• Keep a sharp blade on the machine. Sharp blade cut easier and smoother.

• The blades must be perfectly parallel to the fence to avoid back cutting, whether you are using a single blade or a two-blade system.

• Keep the blades from binding in the cut.

Miki Simpson, Eagle Outlet Store Manager, Eagle America:

• The number one secret is to use the correct blade. For particleboard or MDF, it is suggested to use a triple chip grind blade with 80 teeth. Man-made materials can quickly dull saw blades. With a triple chip grind, the corners of every other tooth are chamfered at 45°. The teeth between are either flat top rakers or alternate top bevel teeth. Each chamfered tooth creates a rough center cut, which is then cleaned up by the rakers. Along with the correct blade, a zero clearance insert is recommended. The insert will provide a solid surface under and right up to the blade. This will give you a safer cut and because the wood fibers are fully supported, they are less likely to fray or tear out.

• Number two would have to be a properly tuned saw. Most importantly, your fence and miter slots in your saw must be aligned parallel to the blade. Your saw blade teeth should be raised so that half the carbide is showing over your stock. By using dust collection, you will deter debris from collecting around your saw teeth and obscuring your cut. A respirator is advised when cutting MDF due to the urea-formaldehyde resin content.

• Number three — on to the actual cuts. For many materials, scoring is one way to assure a good cut. If using thin material, stack cut using double face tape to secure the stock. Masking tape is a good way to keep fibers in place as the cut is being made, but be careful when peeling the tape off after cut.

Joe Arnoldus, Vice President, AA Carbide:

• Nothing cuts better than a sharp blade. Running a dull blade to get a few more cuts will yield a worse cut quality and result in diminished sharpening life of the blade. Running the proper blade configuration with the correct amount of teeth, TCG grind, etc. along with the correct prescore can make a lot of difference, as does a high ATB blade if a prescore is not used.

• Proper sharpening is a must, consisting of properly matching the prescore to the main blade. A poor sharpening to save a few dollars will cost you more in the long run.

• Clean mounting surfaces, because any debris on the blade or the mounting surfaces will cause the blade to wobble, effectively removing most of the teeth from the cut on the sides and increasing the kerf of the cut.

A: Karin Deutschler, President, GUHDO USA Inc.: To ensure an excellent finish on MDF material, whether being cut on a sliding, vertical or panel saw, the most important factors that contribute to a chip-free cut include:

• Selecting a precision saw blade with the appropriate tip configuration for machine/material, tensioned to the motor rpm of the machine it is used on, and a micrograin carbide designed for longer life on composite materials.

• Ensuring proper dust extraction: If the chips/dust are not adequately removed from the cutting path, the impact on horsepower consumption, feed rate, vibration and heat buildup will all affect tool life as well as finish.

• Blade projection (distance from the top of the material to the top of the blade when it is cutting) plays a large role in determining the surface finish as, when this distance is adjusted, the geometry and angle at which the tooth enters the material change considerably. The ideal projection is between 20 and 30mm.

A: John Michel, Director of Sales and Technical Services, LEUCO Tool Corp.:

• Maintain the machine in good operating condition.

• Make sure the tool is the correct one for the job.

• Have dull saws serviced correctly. Properly serviced saw blades should not have a noticeable or significant reduction in performance between sharpenings.
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