VARI-PITCH BAND SAW TECHNICAL BULLETIN VARI-PITCH – QUESTIONS & ANSWERS WHAT THEY ARE - WHY THEY WORK HOW THEY ARE MANUFACTURED DESIGN & GRIND...
VARI-PITCH BAND SAW TECHNICAL BULLETIN VARI-PITCH – QUESTIONS & ANSWERS WHAT THEY ARE - WHY THEY WORK HOW THEY ARE MANUFACTURED DESIGN & GRINDING INFEED SPEED GRAPHS & SAW DEVIATION TABLES
VARI-PITCH BAND SAWS Variable pitch means: that the saw teeth are unevenly spaced in the band saw blade The time has come for band saw technology to catch up to sawing technology. The real challenge has been to make thinner band saw blades, to cut accurately without sacrificing feed speeds and productivity. Over the past 10 years the introduction of the following new processes have met this challenge: Vari-Pitch Thermex® tensioned stabilized for roundsaw & band saws
BAND SAWS VARI-PITCH & THERMEX® VARI-PITCH Proven in service with Canada’s largest and most demanding lumber producers. VARI-PITCH: By increasing and decreasing the tooth pitch of a band saw, you stop the harmonic vibration in a saw, which will eliminate the washboard and allow faster feed speeds up to 15%. THERMEX TENSION STABILIZING: This remarkable new European development increases your recovery, reduces racking and breaking, gives longer service between re-sharps, and cuts bench time substantially.
Since 1994, we have worked closely with some of the leading lumber mill managers in Western Canada to provide them with varied pitch module blades to meet the specific needs of their raw material and equipment. Their interest in this latest advance in saw technology is based on solid evidence that it brings them immediate and substantial advantages: Kerf reduction up to 10% Greatly reduced vibration and noise during sawing Dramatic reduction in washboard Less deviation around knots Improved blade behavior in frozen wood Reduced amps pulled in the cut Reduced bench work
Switching to Vari-Pitch band saws is not difficult, but it does entail the use of high technology in the development of the tooth pattern, skilled workmanship in manufacturing of the band saw manufacture, and close coordination between the filing department and the saw maker. After analyzing how we might overcome this obstacle we decided that there was only one sure solution:
The installation of state-of-the-art CNC laser equipment to cut the varied pitch teeth modules. All our Vari-Pitch band saws are cut by the laser machine and guaranteed to be free of case-hardened teeth.
AMADA QUATTRO LASER
BENEFITS TO LASER CUTTING New Laser Cutting Technology AMADA LASER QUATTRO ENERGY in the form of light is focused and delivered to a spot on the steel. Enough heat is generated to melt the steel. Now with the introduction of inert gas around the nozzle the casehardening of the cutting edge is reduced. The main advantage is: FLEXIBILITY in cutting different and complicated shapes. The main advantage is a decreased heat-affected zone where the structure and the hardness of the steel changes were kept to a minimum.
DESIGNING & GRINDING OF VARI-PITCH SAWS A blade may have several pitch of teeth – normally 4-7 different ones with the same, basic tooth shape – along with different tooth shapes with different pitch. One advantage of unevenly spaced teeth is that they eliminate or dampen the harmonic vibration that causes “washboard” in sawn timber. Feed speeds can be increased as target sizes and kerfs are decreased, and a technique claimed to be efficient in sawing frozen wood. Manufacturing and maintenance of band saw blades with variable pitch can be accomplished with a traditional Armstrong #4 grinder but a CNC grinder allows you to achieve higher accuracy in blade parameters.
The saw teeth will be easier to maintain when the tooth space does not increase or decrease more than .25 inch. This will allow for easier grinding with conventional cams and not allowing the backs to be ground away as the saws are re-sharpened. The teeth pattern for a re saw should have 7 teeth starting with the largest and reducing each tooth pitch until the last two teeth are the same pitch. The teeth with the longest tooth pitch act as a “raker,” pulling sawdust out of the cut. The last two teeth of the pattern which are the smallest pitch and have the same pitch allows for a plaining action for a smooth cut. Saw filers have discovered NO additional advantages in grinding variable pitch saws that have variable gullet depth.
STANDARD TWO INCH TOOTH SPACE DRAWING & INFEED SPEED GRAPH Saw Name: Wheel thickness: Wheel Radius: Hook Angle: Saw Length: Segment Length: Segment Count: Tooth Count:
