I don’t strive for perfect bilateral symmetry in my automotive shaping. The eye and visual primal brain prefer a slight asymmetry as being just right. However, it is important for the overall balance to be quite close.
This is especially key as I make subtle changes to the nose of the 42-year-old Lola T70 MK IIIB I'm renovating for the gentleman who commissioned it. With access to a wealth of new photo data I can see where my original work needs updates.
To measure any point in 3D space there are a multitude of CMM machines that can be staggeringly accurate, down to a tolerance of a micron here or there.
Instead, I'll be using a variety of practical methods depending on the line, shape or surface being measured.
A gridded base gives coordinates for points on each axis to be compared using the centerline as a ‘0, 0, 0’ position.
Vertical 'Z' points are measured with a cobbled-up height gauge.
Positive and negative 'X' points give driver and passenger sides distances. 'Y' points give nose to tail distances.
X, Y, and Z coordinates are compared from side to side and adjustments made.
For the top profile, basic geometry combined with tracing each side's surface onto paper and then folding it in half yields a level of accuracy I can act on.
The folded tracing is checked on a light box to clearly indicate where adjustments are needed.
For quick side-to-side heights a simple level gives immediate feedback.
It can be a slow process, so, I rely mainly on my eyes and fingers to get it to where it feels and looks good. That should be just about right.
I’m familiar with Brown & Sharpe's incredible CMM measuring services having used them to check calibration tools for pharmaceutical test equipment in past engineering projects. Their facilities are mind-boggling, and I fully appreciate their capabilities every time I step onto a jet aircraft.
I’m glad no one’s life depends on my work!
Links to previous Lola T70 posts are below.
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