If your 3D printed parts don't fit together as expected, several factors could be at play:
1. Common Causes
1. Insufficient Clearance in Design — Parts designed with zero or tight clearance won't account for 3D printing tolerances. Solution: Add 0.2-0.4mm clearance for FDM, 0.1-0.2mm for SLA in mating features.
2. Material Shrinkage — Some materials shrink slightly after printing as they cool. Nylon and ABS shrink more than PLA or PETG. Solution: Design with material-specific shrinkage compensation or use low-shrink materials.
3. Dimensional Tolerance Variations — 3D printing has inherent tolerances (±0.1-0.5mm depending on technology). Tight-fitting assemblies may fall outside tolerance. Solution: Test fit with prototypes, adjust clearances as needed.
4. Support Removal Artifacts — Support material on mating surfaces can prevent proper fit. Solution: Clean support residue thoroughly; sand mating surfaces smooth.
5. Warping or Deformation — Large parts may warp slightly during printing or cooling. Thin walls may deflect. Solution: Reinforce thin sections, add ribs, use low-warp materials.
6. Incorrect Scaling — File may have been exported or uploaded with wrong units. Solution: Verify dimensions match your CAD file; resubmit with correct scaling.
2. How to Fix It
Immediate Fixes:
Sand or file mating surfaces lightly to increase clearance
Heat and reshape (for some materials) using a heat gun carefully
Drill out holes that are too tight
For Reprints:
Increase clearances in your CAD model
Specify critical dimensions and tolerances when ordering
Order a test fit sample before committing to quantity
3. Prevention for Future Orders
Design with 3D printing tolerances in mind
Order samples to test fit before production
Communicate critical fit requirements with our team during quoting
👉 If your parts don't fit due to our error or quality issue, submit a support ticket for a reprint.
Learn more on our website:
FAQ — common questions answered
Talk to an Expert — get help with your project
Our Work — see what we produce