|OT -- Help! Imagine a shallow plastic bowl . . .|
Message #1 Posted by Paul Brogger on 10 Apr 2006, 2:55 p.m.
I figure the crafty minds frequenting this site might be able to help, so I'll give it a shot. This is hobby-related, but not likely to be calculatorish.
Imagine a shallow, black, concave plastic bowl or dish, not spherical, but (I think) a surface of revolution -- overall about 24 inches in diameter. (A TV satellite dish might be a good analogue.) This bowl is a piece of a larger, heterogeneous structure composed of several materials, some of which are sensitive to heat, stress and/or moisture.
I want to mark this thing so I can make a planar slice through it. The plan is to cut out a section, flip the cut-out piece, and reattach it, thus reducing the depth of the "dish" while retaining much (if not all) of its inherent strength. (I'm assuming that a properly-oriented planar slice through this thing will give the cut piece an outline that is symmetrical about the "axis of flip".)
I'm thinking I'll position it as necessary, slowly pour in some water until the water's edge describes my desired line of cut, then add something (oil-based paint?) that will float atop the water and cling to the plastic sides. Then, I'll remove the water, let the second substance dry or harden, and I'll have my line drawn as a "high-water mark".
I'm wondering if anyone has any suggestions for what kind of "marker" substance to use? (Again, the object is black.) Any suggestions for an alternative method of accomplishing this task? Suggestions for how to accomplish it on a convex surface as well as a concave one.
I'll share images of my result when I've got it looking presentable.