I'm building a swing set for my children. All of the designs I've seen involve building two A-frames and connecting them at the top with a crossbar/beam from which hang the swings. The A-frames are placed perpendicular to the ground. In addition, it seems that the A-frames are commonly constructed at an angle of 12 degrees from the perpendicular to the ground.
I have several questions:
Where does the 12 degree angle come from?
I've been on swingsets that move too much. I think this is due to a combination of unanchored posts and the angle between the legs of the frame being too little. How do I compute the angle that will provide optimum stability?
Shouldn't the frames be placed at an angle with respect to the ground (e.g. 70 degrees) rather than perpendicular, in order to prevent side-to-side motion?
How would I go about computing the above?
Assumptions that I'm going on include:
- 2 swings
- Adults will swing (up to 200 lbs)
- A-frames will be anchored to concrete piers