Saber saw displacement, velocity and acceleration analysis - Saber saw kinematic analysis

 Saber saw displacement, velocity and acceleration analysis

Saber saw kinematic analysis:

In the below picture shown is a saber saw, in which an offset slider crank mechanism is used to operate the saw blade. The crank wheel is driven by an electric motor, not shown in the below picture. Crank wheel radius is L2, coupler link length is L3, offset is e and crank angle is theta2.

The offset slider crank mechanism is redrawn upside down in the below picture. Angle between vertical and crank is theta2 and angle between vertical and coupler is theta3. Angular velocity of the crank is omega2 and angular acceleration of the crank is alpha2.

In the below pictures described the procedure to derive equations for blade displacement, blade velocity and blade acceleration.

In the below picture described the procedure to derive equation to find angular velocity and angular acceleration of the coupler link.

In the below picture, a problem is solved using Microsoft excel. In this problem crank length L2 is 12.7 mm, coupler length L3 = 44.45 mm, offset e = 25.4 mm, RPM of the crank is 900 and angular acceleration of the crank is zero.

In the below picture Crank angle theta2 is plotted along horizontal axis and along vertical axis displacement of saber saw blade.

In the below picture Crank angle theta2 is plotted along horizontal axis and along vertical axis velocity of saber saw blade.

In the below picture Crank angle theta2 is plotted along horizontal axis and along vertical axis acceleration of saber saw blade.

Slider crank force analysis - problem (Inline slider crank mechanism)

 Slider crank force analysis - problem

In this blog Inline slider crank mechanism static force analysis equations derived using analytical method. 

In the below picture shown is an inline slider crank mechanism, crank length is L2, coupler length is L3 and angle between crank and horizontal is theta 2. There is torque T is applied on the crank clockwise, due to this torque there will be a resting load F on the piston. 

In the below picture shown the forces and reactions on the mechanism.

In the below pictures described procedure to find relationship between applied torque T and resisting force F.

After having derived the equation, a problem is solved using Microsoft excel. In this problem, crank length L2 = 100 mm, coupler length L3 = 400 mm and a torque of 50 Nm is applied on the crank clockwise. For crank angle zero to 90 degrees force on piston F is calculated and plotted in the below pictures.