How to Use Blueprint Pulley and Shaft Collar Packs in Lessons

Quick answer

Start with a simple fixed pulley using a 30mm or 45mm Blueprint Pulley Pack, then add a shaft collar from the Blueprint Shaft Collar & Spacer Packs to lock the axle. Run a 20-30 minute build-test-refine cycle, and keep a spare pulley pack on hand so a worn part never stalls the lesson. This sequence works for grades 4-8 and scales to more complex mechanisms.

Set up the lesson around one mechanism, not a kit tour

Before students touch parts, decide on a single mechanical goal: lifting a small load, changing direction of motion, or transferring rotation. That focus keeps the pulley and shaft collar packs from becoming loose parts. For a first lesson, use a 30mm pulley pack because smaller pulleys fit tighter spaces and make the effect of a single fixed pulley obvious. For a second lesson, switch to 45mm or 90mm pulleys so students see how diameter changes the mechanical advantage and the amount of string travel. You do not need every size on day one.

Build the pulley frame and axle in a fixed order

Have students attach the pulley to a Blueprint beam or frame before threading any string. A pulley that spins freely on a loose axle will wobble and throw the belt. Once the pulley is seated, slide a shaft collar onto the axle and tighten its set screw against the beam or spacer. The Shaft Collar & Spacer Packs include 0.5x High Strength Shaft Collar 10-Packs, High Strength Shaft Collar Set Screw 15-Packs, 0.5x Pitch Shaft Collar 20-Packs, and 0.25x Pitch options, so you can match the collar to the axle pitch rather than forcing a part. If the collar will not grip, stop and check pitch before adding force.

Thread and tension the string before powering anything

Route the string over the pulley groove and tie it to the load. Pull the string by hand to confirm the pulley rotates and the collar stays put. A common mistake is to run a motor or a littleBits mechanical build before this hand test. If the string slips off, the pulley is misaligned or the collar is not spacing the pulley away from the frame. Add or remove a spacer from the Shaft Collar & Spacer Pack to correct the gap, then retest by hand. Only after a clean hand cycle should students connect a motor or a littleBits circuit.

Run a measured test and record one variable

Give each group a simple data sheet: number of pulleys, pulley diameter, load weight, and whether the load rose smoothly. Change only one variable per trial. For example, keep the 30mm pulley and add a second pulley to create a movable system, or swap to a 45mm pulley and compare string travel. This turns a classroom pulley project into a real experiment instead of a craft activity. If a group finishes early, have them test a 90mm pulley and predict the result before they run it.

Troubleshoot with parts, not guesses

When a pulley system fails, check three things in order: collar tightness, pulley alignment, and string tension. A loose set screw on a shaft collar is the most common cause of a pulley that drifts into the frame. A worn pulley groove is the second most common cause of a string that jumps. Keep a spare Blueprint Pulley Pack at the station so a replacement takes seconds. If the build uses littleBits, power the circuit separately first to confirm the motor spins before you connect it to the mechanism.

Close the lesson with a parts audit

Spend the last five minutes having students return collars and spacers to their labeled packs and count pulleys. This is not just cleanup. Missing collars and set screws are the main reason the next class cannot build. A quick audit also tells you which sizes you are burning through, so you can restock the 30mm or 45mm packs before the next unit. Store the AC Power Supply (littleBits) with its USB cable so permanent littleBits creations are ready to run without hunting for a charger.

Your six-step lesson sequence

1. Choose one mechanism goal: Pick lifting, direction change, or rotation transfer. Select a 30mm pulley pack for a first build or a 45mm pack for a second lesson on diameter. Checkpoint: every group can state the goal in one sentence.
2. Mount the pulley and lock the axle: Attach the pulley to the frame, then slide on a shaft collar and tighten its set screw. Match collar pitch to the axle. Mistake to avoid: forcing a 0.25x collar onto a 0.5x axle.
3. Thread and hand-test the string: Route the string over the pulley and pull by hand. Confirm the pulley spins and the collar holds before adding power. Checkpoint: a full hand cycle with no string jump.
4. Run one measured trial: Record pulley size, load, and result. Change only one variable, such as adding a second pulley or swapping to a 90mm pulley. Mistake to avoid: changing two variables and losing the comparison.
5. Troubleshoot in order: Check collar tightness, then pulley alignment, then string tension. Swap in a fresh pulley from a spare pack if the groove is worn. Checkpoint: the system runs three clean cycles.
6. Audit and restock: Count collars, spacers, and pulleys at the end of class. Note which sizes are low and restock before the next unit. Next step: label storage bins by pulley diameter.

Parts that make this lesson run

• Blueprint Pulley Packs: Blueprint Pulley Packs include ten pulleys of a single size and are available in 30mm, 45mm, and 90mm options. Buying one size per pack means you can standardize a class set and replace only the size that wears out.
• Blueprint Shaft Collar & Spacer Packs: Blueprint Shaft Collar & Spacer Packs include 0.5x High Strength Shaft Collar 10-Packs, High Strength Shaft Collar Set Screw 15-Packs, 0.5x Pitch Shaft Collar 20-Packs, and 0.25x Pitch options. Matching collar pitch to your axle prevents slipping and keeps pulleys spaced correctly during student builds.
• AC Power Supply (littleBits): The AC Power Supply (littleBits) is a power adapter and USB cable combo with a 1.5 meter USB to micro-USB cable. It keeps permanent littleBits mechanisms powered during long builds without relying on battery packs.