Will this Z axis anti backlash nut improve your 3D printer accuracy?

Summary

In this video, the creator explores the issue of backlash in the z-axis of a 3D printer, even after upgrades. Backlash, the play between parts, can affect precision, especially in the first layer of printing. While anti-backlash nuts are designed to eliminate this by keeping threads always engaged, they may not be effective under the weight of the printer's gantry. The video suggests that instead of relying on mechanical solutions like anti-backlash nuts, which can add unnecessary friction, it's better to focus on aligning the axis and removing binding points to minimize backlash and improve z-axis accuracy.

Takeaways

• 🔧 Backlash is the play between two parts that should be fixed together, often caused by loose fits, improper machining, wear, or design clearances.
• 🔄 It's a common issue in mechanisms like gears, where a small movement of the drive gear doesn't immediately move the driven gear due to clearance.
• 🖨 In 3D printers, backlash in the z-axis can cause inaccuracies, especially noticeable during the first layer print or when homing the printer.
• 🔩 The z-axis backlash is due to the clearance between the lead screw and the lead nut, which can increase over time due to wear.
• 🌀 Spring-loaded anti-backlash nuts are designed to keep the threads of the nut always engaged with the screw, minimizing backlash.
• ⚖️ However, in applications with heavier loads, such as a 3D printer's z-axis, the weight can compress the spring, causing disengagement and backlash.
• 🔩 A stiffer spring could theoretically handle the load, but it would increase friction, overwork motors, and accelerate wear on components.
• 📈 Mounting the nut above the gantry can use gravity to help maintain thread engagement, but it's not always necessary if screws are properly aligned.
• 🔒 Anti-backlash nuts can add friction, which might prevent the z-axis from dropping when the printer is powered off, but they don't improve accuracy.
• ❌ The video concludes that anti-backlash nuts do not improve the accuracy of the z-axis in 3D printers and that other mechanical adjustments are needed to minimize backlash.

Q & A

What is backlash in the context of machinery?

Backlash is the undesirable play between two parts that are supposed to be fixed together, caused by loose fits between parts due to improper machining, normal wear and tear, or design clearances necessary for a part to function.

Why is clearance necessary between the teeth of two gears?

Clearance between the teeth of two gears is necessary to achieve smooth operation and minimize wear, but it can lead to backlash, which is the movement of the drive gear without the driven gear moving when the direction changes.

How does backlash affect the z-axis of a 3D printer?

Backlash in the z-axis of a 3D printer can cause the printer to assume movement has occurred when in reality there is no movement, especially during the first layer print or when the direction of movement changes, which can lead to inaccuracies.

What is the role of the lead screw and lead nut in the z-axis mechanism of a 3D printer?

The lead screw moves the gantry, and the lead nut engages with the screw to ensure movement. However, there can be clearance between them, which can cause backlash when the direction of movement changes.

How does a spring-loaded anti-backlash nut theoretically eliminate backlash?

A spring-loaded anti-backlash nut uses a spring to force the nut's parts to always be engaged with the screw, ensuring thread engagement in both directions of movement and theoretically eliminating backlash.

Why might a spring-loaded anti-backlash nut not be effective in a 3D printer's z-axis?

The weight of the gantry in a 3D printer's z-axis can be greater than the force of the spring in the anti-backlash nut, causing the nut to lose engagement with the threads and not eliminate backlash.

What is the potential downside of using a stiffer spring in an anti-backlash nut?

Using a stiffer spring can increase friction, overwork stepper motors, wear out brass nuts faster, and potentially cause binding in the mechanism.

Why might mounting the nut above the gantry help with thread engagement?

Mounting the nut above the gantry allows gravity to work in favor of thread engagement, as the weight of the gantry helps keep the threads engaged even when the direction of movement changes.

Can the anti-backlash nut increase friction to prevent the z-axis from dropping when the printer is powered off?

Yes, the added friction from an anti-backlash nut can help prevent the z-axis from dropping when the printer is powered off, although it does not improve the accuracy of the z-axis.

What is the final verdict on using anti-backlash nuts for improving the accuracy of the z-axis in a 3D printer?

The video concludes that anti-backlash nuts will not help improve the accuracy of the z-axis if the goal is to reduce backlash. However, they can be beneficial for increasing friction to prevent the z-axis from dropping when the printer is powered off.