Developing Interpenetrated Parts

Developing Interpenetrated Parts

This is where the Grade 11 topics combine: find the curve of interpenetration, then develop the parts so the joint can actually be cut from flat sheet.

The sequence:

1. Construct the curve of interpenetration using generators.
2. For the branch, draw the stretch-out line of length π × D and divide it into the same number of parts as the generators.
3. At each division, set off the height of that generator up to the interpenetration curve, read from the elevation.
4. Join the points with a smooth curve. That curve is the profile the branch must be cut to.
5. For the main pipe, develop it separately and mark the hole the branch passes through, plotted from the same points.

Both parts come from the same points. The branch's cut profile and the hole in the main pipe are two views of one intersection, so they are plotted from a single set of intersection points. Constructing them independently guarantees a mismatch.

Worked example. A 45° branch into a header: the branch's developed edge is an asymmetric curve, and the hole in the header is an elongated oval. Both come from the same twelve points.

Core checkpoint: One set of intersection points serves both developments. Plot once, use twice.