making – splines – part 2
On the previous page an external spline was made to fit an existing internal spline. The situation this was being used in was rather undemanding. This meant it was possible to overlook a potentially serious fault.
Where two parts are connect using splines large forces can be involved. All of these forces are concentrated on the edges of the splines. In order to maximise the strength of the join it is important that all the edges of the splines touch each other as accurately as possible and that the area of the touching is maximised.
Ideally this means that the edges of the individual splines would be radial.
This would mean the shape on the female part would be wedge shaped. This is too difficult to make. As a compromise this shape is made with parallel sides. This then means that the sides of the individual splines on the male part have to be made parallel. The two sides of any individual spline have to be cut in two operations when using an end mill. Another way of doing this is to use two side and face cutters on a horizontal or stub arbor as shown
fig cutting a spline on the male part