Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Just a couple of "off the cuff" comments on this technique Jim.

First off, I'll say simple is best whenever you can manage it, and I think this technique truly qualifies in that category!

While the mechanical capture between the point of the center drill and the "peak" of the cylinder is key, gravity can still have some effect on the results obtained, so I'd suggest always trying to use the rule as close to its true center as possible, and perhaps best not to use one that has a hole and a different profile on one end, such that the balance point is not true center.

Another point to consider is to make sure that the place to be drilled has no dings, dents or other deformities within the bearing area of the rule you are using, as that would cause an aberrant deflection, different from a true tangent at the "peak" of the cylinder.

Just my 0.02 cents worth.