how to draw spur gear tooth profile with 0.4 mm module and 43 and 19 teeth respectively?
The procedure for drawing the spur gear tooth profile in you case is given below.
The first step you should take is to calculate the Pitch Diameter of the Spur Gear by multiplying the module with the number of teeth.
In your case
0.4mm X 43 = 17.2mm
and
0.4mm X 19 = 7.6mm
The next step is to find out the angle between each teeth by dividing 360 degrees with the number of teeth.
360deg / 43 = 8.372deg
and
360deg / 19 = 18.947deg
By using these two important measurements you would be able to make the spur gear tooth profile.