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Tolerance Fit Explorer

Run the Tolerance Fit Explorer MicroSim Fullscreen

You can include this MicroSim on your website using the following iframe:

<iframe src="https://dmccreary.github.io/robot-arm/sims/tolerance-fit-explorer/main.html"
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Description

Set a designed hole size, a printer size error and a mating part size, and see whether the printed hole is too tight, snug, a good sliding fit or loose. Then predict the outcome for six cases before it is shown. Used in Chapter 7.

The picture is a cross-section of a printed pocket with the mating part above or inside it. The gap is drawn larger than life so you can see it. The bar under the picture shows the four clearance zones, and a marker shows where the clearance falls.

The servo body width (24.7 mm) and the servo's output spline size (5.9 mm) are from Feetech's STS3215 data sheet, and 3.0 mm is the standard M3 screw shaft. The designed hole sizes and the printer errors are illustrative values written for this MicroSim.

Lesson Plan

Grade level: Middle school and up (age 12+). Time: 10 to 15 minutes.

  1. Explore. Move the three sliders and watch the printed hole size, the clearance and the outcome. Notice that a printer error of −0.10 mm turns 0.30 mm of designed room into 0.20 mm.
  2. Find the edges. Make the clearance exactly 0.00 mm, then 0.10 mm, then 0.30 mm. Which zone does each one land in?
  3. Six cases. Switch to Six cases. For each one, work out the printed hole and the clearance in your head or on paper, then choose an outcome. You get one try per case.
  4. Think about it. Why is a bigger hole not always the safer choice? Why is a clearance of zero not a perfect fit?

Specification

The learning objective, evidence of mastery and content for this MicroSim are specified in Chapter 7: 3D Printing, Fasteners, and Tools.