When parts don't fit

Why it happens

Every printer prints slightly differently. Holes often come out a little smaller than designed and outer edges a little larger, especially on the first layers. The difference is usually 0.1 to 0.3 mm, which is enough to make a snug fit too tight.

Use the clearance setting

Tools with parts that fit together (lids, hinges, joints, threads, holders) often have a clearance or tolerance setting. That is the gap between the parts.

• Too tight: raise the clearance by 0.05–0.1 mm and print again.
• Too loose: lower it by the same amount.
• Print a small test first if the tool lets you make a small version.

Check your printer

• Elephant's foot: a first layer that bulges out makes the bottom edge too wide. Lower the bed temperature a little, or enable elephant's foot compensation in your slicer.
• Over-extrusion makes everything slightly too fat. Calibrate the flow rate. The 3D Printing category has calibration tools for this.
• Holes for screws and magnets can be cleaned up with a drill bit of the right size.

Measure what you fit to

When a tool asks for a size (a pipe, a battery, a phone), measure the real object with calipers rather than using the size on the packaging. Then let the clearance setting handle the gap.