Understanding Tolerance

Objectives and Overview

This lesson introduces the concept of tolerance in 3D design. When 3D printing you have to be aware of tolerances. Testing tolerance is fundamental to figuring out how to fit printed parts together.

Lesson Objectives

  • Understanding tolerance in physical materials.
  • Understand why tolerance needs to be considered when designing 3D prints that are integrated with physical objects.
  • Measure the filament and track variations in filament spools.

Working with Tolerance

One way to think about tolerance is that its how much wiggle room you need between pieces. Tolerance varies depending on the type of printer and filament that you decide to use. Understanding and considering this fluctuation is crucial when doing designing with precision.

Filament Tolerance

The filament used with 3D printers is often not precise and uniform in diameter. In order to understand how these changes impact your designs and prints, you’re going to actually take physical measurements of the filament.

Material tolerance is how much measurement is allowed to vary. It’s nearly impossible to get completely accurate measurements and consistent values for each filament roll, so the tolerance is how much the measurements will vary.

For instance, when manufacturers make filament, they try to get it as close to 1.75mm as possible, but if you actually measure the thickness, it will vary usually from 1.7 to 1.8 and sometimes even higher or lower. The consistency of the filament thickness across the entire roll is occasionally used as a measure of the filament quality.

Activity: Measuring the Filament Tolerance

Using digital calipers to measure filament tolerance


  1. Get some strands of filament that are about 3′ in length.
  2. Measure both ends of the filament, as well as the center. Compare the measurements.
  3. Find the filament manufacturer’s website and see if they listed the filament tolerance.
  4. Compare your measurements with what’s listed.
  5. Answer the following questions:
    • Describe what tolerance is.
    • List the measurements of the filament you measured and include a photo.
    • List the tolerance of at least 2 filament companies and add a link to their website.