How to Draw an Involute Spline

Mechanical drawing has come a long way with the invention of the computer and CAD programs. But sometimes you may find it necessary to do some of your gear drawing by hand. An involute 'spline' is closely related to involute 'gear' teeth, except in size. The teeth of the involute spline are half that of involute gears, and have a thirty degree pressure angle which will need to be taken into consideration for your drawings.

Things You'll Need

• Pencil
• Paper
• Marker
• Ruler

Instructions

1. 

   Begin your drawing by making two circles, one inside the other. The inner circle should have a notch cut out at the top of it, as the diagram shows.

2. 

   Next, begin drawing the spline teeth. You can use a ruler if it helps you to make your lines straighter. You can also use the ruler to help you mark the teeth equal distances apart. The spline teeth are simply triangles, minus the points. If it is easier, you can draw the top spline teeth, and turn the paper around to draw the remaining teeth.

3. 

   Draw the remaining involute spline teeth by turning the paper around. If you have been using your ruler for precise lines and measurements, continue to do so. Continue drawing until all of the teeth are complete.

4. 

   Turn the paper back to the start position and draw in the half moon tips at the top of each of the involute spline teeth.

5. 

   Finalize the involute spline drawing by drawing the back circle of the gear in between each of the teeth. These curved lines should be approximately 1/8th of an inch away from the original circle.

Tips & Warnings

• In your drawings, pay close attention to the differences in the gears. The more visual you become, the easier it will be for you to make clearer drawings of the varying types of gears.

• When you are first beginning to draw, use a pencil. Otherwise, you will not be able to make corrections. Afterward, use a marker to make your lines bolder.

Resources

• Tech Drawing
• AutoCad