Cracking in a saw gullet
| reason of cracking |
suggested solution |
| the radius of saw gullet’s rounding too small |
sharpen, thus increasing the radius |
| incorrect saw strain - too small or too big |
measure the saw strain and set it according to the machine DTR |
| the diameter of guide pulleys too small |
use a thinner saw |
| cutting edges went in contact with the material before proper operating speed was achieved |
start cutting no sooner than proper operating speed is achieved, according to DTR |
| burn marks in saw gullets after sharpening |
grinding wheel mismatched (too hard); insufficient cooling |
| dull blade |
stop working, sharpen the saw along all its length (tool rake angle, tool orthogonal clearance angle) |
| incorrect setting (too small, too big, irregular) |
correct the saw setting |
| leaving the saw strained after work |
adhere to recommendations given |
| saw overheated – continuous work with no rest |
adhere to recommendations given |
| tool rake angle incorrect for a given wood hardness |
sharpen the saw – maintain the proper tool rake angle |
Cracking at the back side
| reason of cracking |
suggested solution |
| incorrect saw strain - too small or too big |
set the strain according to DTR |
| excessive feed - saw overload |
decrease the feed |
| guide pulleys in poor condition, not aligned |
regulate the guide pulleys, correct their alignment |
| misaligned, worn or dirty guide rolls |
move the rolls close to cutting zone, clean and align them |
| incorrect width of guide rolls for a given saw width |
match proper guide rolls |
| continuous work with no rest |
adhere to recommendations given |
| vibrations of pulleys or gears, axial run-out of pulleys |
bearings worn, need replacement |
Wavy motion of a saw
| reason of wavy motion |
suggested solution |
| incorrect setting (too small, no symmetry) |
adhere to recommendations given |
| excessive surface imperfections left after sharpening |
smoothen the sharpened surface and correct setting |
| low cutting speed, excessive feed |
check and correct tension of the saw driving belts; decrease the feed |
| worn bearings of pulleys, rolls, play in the saw strain system |
replace (repair) |
| incorrect saw strain |
set the strain according to DTR |
| unstable locking of material cut |
lock the material firmly in fixed position |
| cutting edge of band wandering along the guide pulleys or rolls (decreasing the setting at one side) |
use a broader saw, correct the setting symmetry |
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