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Session 10: The Mismatch Activity

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Session 10

The Mismatch Activity

Last Session

You calculated min and max for one part at a time.

Today: what happens when two parts, each with their own tolerance, have to fit together?

Worst-Case Fit

Peg spec: 0.250 in ± 0.005 in (min 0.245, max 0.255)

Hole spec: 0.250 in ± 0.005 in (min 0.245, max 0.255)

Worst-Case Fit

Worst case: the peg comes out at its max (0.255), the hole comes out at its min (0.245).

The peg is now bigger than the hole — even though both parts individually passed their own spec.

Both Parts "Passed." They Still Don't Fit.

A spec sheet check on each part, alone, doesn't guarantee the assembly works.

Today's Activity: Fit Test

  1. Measure both parts of your pair
  2. Predict whether they'll fit
  3. Physically test the fit
  4. Diagnose any mismatch against your numbers

Two Things to Remember

Trust your measured result over the spec sheet's assumption.

The spec tells you what should happen in theory. Your caliper and your physical test tell you what actually did.

Two Things to Remember

A mismatch isn't a failed activity.

A pair that doesn't fit, diagnosed clearly, teaches the exact same lesson as a pair that does. Explaining why matters more than which outcome you got.

Next Time

Session 11: Measurement & Data Collection Lab

Repeated-trial measurement, logged like real data — the exact skill the launcher project runs on later.

'F' → Fullscreen

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Build

Step 1: Measure Your Pair

Using your Session 6 caliper technique, measure both parts of your assigned pair. At least 2 trials each.

PartTrial 1Trial 2
Part A
Part B

Step 2: Predict

Based on your measurements (and each part's spec, if your instructor provided one), predict: will these two parts fit together cleanly, fit tight, or not fit at all? Write your prediction down before testing.

Step 3: Physical Fit Test

Actually assemble the pair. Record what really happened.

Step 4: Diagnose

If your prediction didn't match reality, use your measured numbers to explain why — not just "it didn't fit."

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Checkpoint

Before you submit, confirm:

  • You measured both parts, not just one
  • You wrote your prediction down before the physical test, not after
  • Your recorded result is honest, whether or not it matches your prediction
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Reflection

Answer the following questions before submitting your work.

  1. Did your pair fit as predicted? If not, what does the mismatch tell you about how the two parts' individual tolerances interacted?
  2. Why is a measured, tested result more reliable than a spec sheet's theoretical assumption?
  3. This exact idea — trust your measured data over a theoretical prediction — comes back later, during the launcher project's calibration phase. Why do you think an empirically-tested model might beat a theoretical prediction there too?
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Submit

Submit your measurements, prediction, fit test result, and reflection.

Activity Complete