This my remix of Winter Catapult - Snowball Fight by MacshayCreations published on Thingiverse. It replaces the 3D printed in-place bearings with 17287 2RS bearings.

17287-2RS bearings from Ali-Express

3D printing

Start by 3D printing the attached files. Layer height is 0.2mm. Supports are not required. The new STL files replace the following files:

• "Catapult - Arm.stl" replaces "Arm_Catapult_Macshay_Creations.STL".
• "Catapult - Gear_Axle.stl" replaces "Gear_Shaft_Catapult_Macshay_Creations.STL".
• "Catapult - Left.stl" replaces "Left_Side_Catapult_Macshay_Creations.STL".
• "Catapult - Right.stl" replaces "Right_Side_Catapult_Macshay_Creations.STL".
• "Catapult - Spring_1.stl" replaces "Spring1_Catapult_Macshay_Creations.STL".
• "Catapult - Spring_2.stl" replaces "Spring2_Catapult_Macshay_Creations.STL".

17287-2RS Bearings

The left and right sides and catapult arm take two 17287-2RS each. Each bearing has an insert to fit the hexagonal shafts. Start by 3D printing "Catapult - Inserts.stl". These inserts are super glued into the middle of each 17287-2RS bearing.

Super glue the bearings into the left and right sides and catapult arm. Note that each piece uses two bearings.

Add the bearings to the left and right sides and catapult arm

Gear shaft and springs

The gear shaft has been modified to take two M2 3.2mm diameter by 5mm high brass inserts at each end. This was done so that the springs can be screwed onto the shaft. The new springs have a hole to take a M2 6mm screw.

Heat press a M2 5mm x 3.2mm Brass Insert into each end of the Gear Shaft

Use a M2 6mm screw to hold the spring to the Gear Shaft

Assembly

I strongly suggest for most of the construction you follow this video from MacshayCreations.

Conclusion

Thanks MacshayCreations for a great model. I hope this addition helps others who maybe having problems 3D printing the in-place bearings that is part of the original design.

The completed build