My apologies for pirating this post - but the beauty of the simple genius of the Vernier scale fits in this story, I hope you find it amusing.
Background; weeks prior to this I had been assigned to build a mechanism to rotate in 45 degree increments to an accuracy of less than 1/10 of one degree. In brief it was quite the education.
True story,
I was with a friend who races karts at a national level event [Organization name withheld to protect the guilty]. The class uses 4 cycle Briggs & Stratton engine powered with methanol, a glorified lawnmower engine hurling us fools on THE Daytona speedway up to 98mph - go figure.
The post race tech includes "degreeing" the cam. This is a procedure where a degree wheel is attached to the crankshaft and the valve lift is checked with a dial indicator, there is a maximum lift at a given degree allowed. After attaching an eight inch diameter plastic disk with silk screened graduations.. mind you this is a commercial not home made, dare I say it "instrument" - the man proceeds to attach the pointer, a bent 1/8" diameter piece of aluminum welding rod, clearly the pointer end cut with the dullest of tool available... after some fiddling and peering over very thick glasses the man proceeds to declare the cam illegal by one quarter of a degree.
STUNNED - I was in such a state of shock I was incapable of uttering so much as a squeak, "sir, the line alone is that wide" I finally think but fortunately the word only come out as a questioning "really?" My friend looks at me as the man is saying "Who is your engine builder? Your looking at him!" my friend says. "Oh, well in that case I'll let you pass but I'm going to confiscate that cam until after the next race." Without another word we whipped off that side cover and handed the man the camshaft and left as quickly as we could. "Whats the rush?" I asked as my friend as he tossed the disgorged engine in the seat and hustled away - "The bore is 0.01" over and were only allowed 0.03." "So" I say, "Did you see that 12" wooden ruler on the bench? I'm not taking any chances!"
The rest of the story -
You see in the weeks before I had explored the Vernier scale concept and applied it to a carefully scribed plate that we used with our already fairly accurate custom made 16" diameter degree wheel, we did indeed find that we could gain a bit more lift because we were erring on the side of caution not knowing our true accuracy without the scale. If I had the wheel with us I would have shown the man he was close but not exactly onto the one half degree advanced that we knew that brand of wheel he was using to be, we compared four brands, all bad to some degree [pun].
- best to leave sleeping dogs lie.
It is too my simple mind almost magical the Vernier scale, so simple an idea I would never have thought of it.
Regards,
B
