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Should the edge be horizontal?
#1
Sometimes, the fulcrum causes the knife edge to fall out of level. Is it OK to measure like this?


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#2
From my experience what you are showing won’t matter. I wouldn’t do 45° but a bit off level seems to make no difference. If it bothers you just don’t use the fulcrum and hand-hold the blade. Hand holding works just fine for me.
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#3
Grepper has it right SHARPCO, we can distinguish little difference in measurement results if the edge is at a small angle at the beginning of the measurement. If you stop and think about it. The measurement will always be taken at  angle if you begin horizontal due to depression of the test media. We always use the fulcrum with knives. Just a matter of habit we suppose.
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#4
(02-23-2018, 11:32 PM)SHARPCO Wrote: Sometimes, the fulcrum causes the knife edge to fall out of level. Is it OK to measure like this?

SHARPCO, we put the following leaflet in the PT50 sold to customers (the #3 answers your question) - this is just a brief summary of what we read in EOU manuals.


PT50 Factors Affecting Accuracy

Test media slack - falsely increases the score.

Blade is not centred against the test line gap - variance starts if the blade is off the gap centre by more than 1.5 mm. Correct by repositioning the Fulcrum.

Edge not vertical - variance starts if the blade is slanted by more than 5 degrees off the vertical plane.

Knife edge does not cross the test line at 90 degrees (right angle), i.e. Test Fixture is not squarely aligned with the Fulcrum.
http://knifeGrinders.com.au
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