3D Printing for Bearings – A Complete Beginner’s Guide to Shafts, Shaft Collars, and Metal Upgrades

Bearings are one of those hidden heroes in mechanical design. You find them in everything from fidget spinners to bicycles, 3D printers, and even high-end robotics. They allow smooth, low-friction rotation — but a bearing can’t do its job alone.

It needs support. It needs something to hold it, something to spin on, and something to keep it in place.

That’s where shafts and shaft collars come in.

And here’s the good news: you can 3D print both of these components yourself. Even better — if you need extreme strength, you can get them metal 3D printed without owning expensive equipment, thanks to services like PCBWay.

In this post, we’re going to break everything down in plain English:

• What bearings, shafts, and shaft collars are
• How to design and 3D print shafts for strength and accuracy
• How to design and print shaft collars
• When and why to upgrade to metal shaft collars
• How PCBWay can make your parts in aluminum using SLM

1. Bearings: The Basics

A bearing is a mechanical component that reduces friction between moving parts. Imagine trying to roll a heavy box across the floor — it’s hard. But put that box on wheels (which have bearings), and suddenly it’s effortless.

The most common type you’ll encounter in small mechanical projects is the ball bearing — a metal ring containing tiny steel balls that roll between an inner ring (the part that spins) and an outer ring (the part that stays still).

Key terms to know:

• Inner Diameter (ID): The hole size where the shaft goes.
• Outer Diameter (OD): The overall size of the bearing.
• Width: The thickness of the bearing.

Example: A 608 bearing (the one used in fidget spinners) has an ID of 8 mm, OD of 22 mm, and width of 7 mm.

2. Shafts: The Backbone of the Assembly

A shaft is simply a rod that fits through the bearing’s inner ring and transfers motion. It could spin a wheel, hold a gear, or drive a pulley.

Why Shaft Printing Orientation Matters

When you 3D print a shaft vertically (standing up), the layer lines run across its length. This is bad for strength — it’s like stacking bricks on top of each other and then trying to bend them; they’ll snap along the seams.

Printing the shaft horizontally makes the layer lines run along its length, which drastically improves tensile strength and makes the shaft much more resistant to snapping under load.

The trade-off?

• You’ll need supports for the circular shape.
• The surface where the supports touch will require cleanup.

But the increase in durability is worth the extra effort, especially for functional parts.

Getting the Right Fit

Bearings are precise, and your shaft must be too. For FDM printing, a general rule is:

• For a press fit: Make the shaft 0.1 mm larger than the bearing’s inner diameter.
• For a slip fit: Match the bearing’s inner diameter exactly or go 0.05 mm smaller.

If your prints tend to be slightly oversized or undersized, you may need to tweak this number for your specific printer and filament.

Materials

• PLA: Rigid and easy to print, but brittle under impact.
• PETG: Tougher, slightly flexible, good for general use.
• Nylon: Excellent strength and wear resistance, but trickier to print.

3. Shaft Collars: The Unsung Heroes

A shaft collar is a small ring that fits around a shaft and locks into place to prevent movement along the shaft’s axis. Think of it as a clamp that stops your bearing, gear, or pulley from sliding off.

Basic Shaft Collar Design

In CAD software like Fusion:

1. Bore Hole: Match your shaft diameter exactly.
2. Set Screw Hole: Perpendicular to the bore; holds the collar in place.
3. Chamfers/Fillets: Small beveled or rounded edges help prevent cracking.

For 3D printed collars, you can design the hole to be self-threading for a screw, or you can tap it with a thread-cutting tool after printing.

Printing Orientation

Print collars flat on the bed. This puts the layer lines perpendicular to the clamping force, making the collar much stronger. If you print them standing up, they’ll split when you tighten the screw.

Types of Shaft Collars

• Set Screw Collars: The most basic type — uses a single screw to grip the shaft.
• Clamp Collars: A slit and screw clamp the collar around the shaft evenly.
• Two-Piece Collars: Split into two halves for easy installation without removing other components.

4. Real-World Testing of Printed Shafts and Collars

When I tested PLA shafts with PLA collars, they worked fine for light-duty applications like small spinners and prototypes. PETG offered a nice improvement in impact resistance.

Nylon shafts paired with PETG collars performed best in terms of long-term wear and clamping ability, especially in robotics applications where vibration is common.

However, in high-speed or heavy-load setups, even nylon collars can deform over time — which led me to try metal shaft collars.

5. Stepping Up to Metal — PCBWay’s Aluminum Shaft Collars

Plastic parts are great for speed and low cost, but sometimes you need a material that won’t creep, crack, or wear down — no matter the load. Aluminum is light, strong, and corrosion-resistant, making it perfect for shaft collars in demanding applications.

What is SLM?

PCBWay uses Selective Laser Melting (SLM) to create aluminum parts. In simple terms:

• A thin layer of aluminum powder is spread over a build plate.
• A high-powered laser fully melts the powder where your part’s cross-section is.
• This repeats layer by layer until the part is complete.

The result is a fully dense, solid metal part — strong, precise, and ready for demanding mechanical use.

My Design Process

I took my Fusion 360 plastic collar design and prepared it for SLM by:

• Tightening tolerances slightly for a precision bore.
• Adding deeper counterbores for the set screw head.
• Including fillets for stress reduction without sacrificing strength.

Ordering from PCBWay

1. Upload the STL file to PCBWay’s quoting system.
2. Choose Aluminum AlSi10Mg.
3. Confirm sizing and quantity.
4. Place the order and wait for shipping.

A few days later, the parts arrived with a fine, matte texture from the powder bed process.

Performance in Testing

These SLM aluminum collars didn’t just survive my tests — they didn’t change at all. No cracking, no loosening, no visible wear. I could tighten the set screw as much as I wanted without damaging the part or the threads.

6. Maintenance and Tips

Whether you use plastic or aluminum shaft collars:

• Keep shafts clean: Dirt and debris increase wear.
• Avoid over-tightening: Even metal can strip threads if abused.
• Check regularly: Especially in vibration-heavy setups.
• Lubricate lightly: Helps reduce friction and prolongs bearing life.

7. Conclusion

If you’re working with bearings, 3D printing your own shafts and collars is a great skill to have.

• For quick, low-cost projects: PLA or PETG shafts and collars get the job done.
• For tougher builds: Nylon improves longevity.
• For the ultimate durability: Aluminum collars from PCBWay using SLM are practically bulletproof.

By understanding orientation, tolerances, and material choice, you can produce high-quality bearing components tailored to your exact project needs — and you don’t even need a machine shop to do it.