Important Warning: This is a historical archive text, not a current machine calculation, risk assessment or operating manual. The number of revolutions, stroke, displacement, forces, coefficients and tabular values must be checked according to valid regulations, manufacturer’s documentation and specific production conditions.
This text is not a machine offer or service documentation of Savo Kusić. The current offer is focused on windows, doors and related solutions.
Number of revolutions and stroke size
The number of revolutions of the shaft determines the productivity of the frame saw. The higher the number of revolutions, the higher the productivity at the same stroke. However, without prior calculation, the number of revolutions of the shaft should not be increased, as this leads to a large increase in vertical inertial forces, which can cause frame-saw failure. The number of revolutions of the shaft ranges from 200 to 350 per minute in modern frame saws. The frame with the tensioned saws moves up and down and in this way the logs are cut. The path taken by the saw frame from its lowest to its highest position is called the frame-saw stroke length.
The size of the stroke affects the productivity of the gatekeeper. With an increase in stroke, with the same number of revolutions, the productivity of the gater increases. The stroke size can only be increased if a calculation is made beforehand.
Step - displacement is the movement of logs during one full turn of the gater shaft. The size of the step by the power of the drive motor can be determined according to the formula:
Log displacement and historical patterns
Δ = 140N / Σhn mm where Δ is the step of a log or beam during one full revolution of the gater shaft, mm; N - motor power k x s; Σh - the sum of the heights of the cuts in the middle of the length of the log; h - the sum of the heights of the cuts in the middle of the length of the log, m; n - number of revolutions of the gater shaft, min.
The sum of the heights of the cuts can be calculated according to the formula Σh = α x dsr x z, where α is the coefficient, which characterizes the mean height of the cuts and which is taken 0,65 - 0,80 when cutting logs. When the beam is cut, this coefficient is equal to unity; dsr- diameter at the middle of the log; z - number of saws tightened in the frame.
For cutting oak, the amount of displacement is 60%, for larch - 85%, for beech - 70%, for birch - 80% of the displacements for pine and spruce given in table 1.
Tabular data for vertical gutters
| D | 10-12 | 13-14 | 15-16 | 17-18 | 19-20 | 21-22 | 23-24 | 25-26 | 27-28 | 29-30 | 31-32 | 33-34 | 35-36 | 37-38 | 39-40 | 41-44 | 45-48 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| α | |||||||||||||||||
| 0 | 33 | 33 | 31 | 28 | 26 | 24 | 22 | 20 | 19 | 17 | 16 | 15 | 14 | 13 | 12 | 12 | 11 |
| 100 | – | – | 32 | 29 | 26 | 25 | 23 | 20 | 19 | 17 | 16 | 15 | 14 | 13 | 12 | 12 | 11 |
| 120 | – | – | – | 30 | 27 | 26 | 24 | 21 | 19 | 17 | 16 | 15 | 14 | 13 | 12 | 12 | 11 |
| 140 | – | – | – | – | 28 | 26 | 24 | 22 | 20 | 17 | 16 | 15 | 14 | 13 | 12 | 12 | 11 |
| 160 | – | – | – | – | – | 27 | 24 | 23 | 21 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 |
| 180 | – | – | – | – | – | – | 25 | 24 | 22 | 19 | 17 | 16 | 15 | 14 | 13 | 12 | 11 |
| 200 | – | – | – | – | – | – | 24 | 23 | 20 | 18 | 16 | 15 | 14 | 13 | 13 | 11 | |
| 220 | – | – | – | – | – | – | – | – | 24 | 21 | 19 | 17 | 15 | 15 | 13 | 13 | 11 |
| 240 | – | – | – | – | – | – | – | – | – | 22 | 20 | 18 | 16 | 15 | 14 | 13 | 11 |
| 260 | – | – | – | – | – | – | – | – | – | – | 21 | 19 | 17 | 16 | 14 | 14 | 12 |
| 280 | – | – | – | – | – | – | – | – | – | – | – | 21 | 18 | 16 | 15 | 14 | 12 |
| 300 | – | – | – | – | – | – | – | – | – | – | – | – | 20 | 16 | 16 | 15 | 12 |