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Troubleshooting — Hardware Issues

This page provides solutions for common mechanical and hardware problems encountered when building or using PrintExo.

1. Mechanical Fit Problems

Parts Do Not Fit Together

Symptom Possible Cause Solution
Parts too tight Over-extrusion, elephant's foot Sand mating surfaces, calibrate flow rate
Parts too loose Under-extrusion, shrinkage Reprint with adjusted settings, use shims
Misaligned holes Print warping, incorrect orientation Reprint with brim, verify print orientation

Holes Too Tight or Too Loose

Issue Cause Solution
M3 bolt won't thread Hole undersized or filled with stringing Ream with 2.5 mm drill, tap with M3 tap
Bolt spins freely Hole oversized, stripped threads Use thread-locking compound, reprint part
Bearing won't press in Hole undersized Ream carefully, avoid cracking
Bearing falls out Hole oversized Use retaining compound (Loctite 648)

Interference Between Moving Parts

  • Check for: Residual support material, stringing, over-extrusion blobs
  • Solution: Carefully trim with flush cutters, sand contact surfaces
  • Prevention: Increase clearance in CAD, improve print cooling

2. Gearbox Issues

Excessive Backlash

Cause Solution
Worn gear teeth Inspect and reprint affected gears
Loose bearing fit Replace bearings, check housing dimensions
Sun gear not centered Reassemble with proper alignment (see Assembly Guide)

Unusual Noise (Grinding, Clicking)

Noise Type Likely Cause Solution
Grinding Gear teeth interference, debris Disassemble, clean, check tooth mesh
Clicking Chipped tooth, foreign object Inspect teeth, remove debris
Whining Tight mesh, insufficient lubrication Verify clearances, apply light grease

Jamming During Rotation

  1. Check sun gear centering — misalignment causes binding
  2. Inspect planet gear bearings — seized bearings lock rotation
  3. Verify ring gear alignment — ensure it's seated properly
  4. Look for debris — plastic shavings can jam teeth

3. Structural Failures

Cracked Printed Parts

Location Likely Cause Solution
Around bolt holes Over-tightening Reprint, use torque-limiting technique
Layer lines Weak layer adhesion Reprint with higher temp, slower speed
Stress concentration Design issue Reinforce with epoxy, report for CAD update

Layer Delamination

Cause Solution
Low nozzle temperature Increase temp by 5–10°C
Fast print speed Reduce speed for structural parts
Moisture in filament Dry filament before printing
Poor bed adhesion (warping stress) Use enclosure, increase bed temp

Deformed Components

Symptom Cause Solution
Warped flat surfaces Heat, inadequate cooling Reprint with better cooling, use enclosure
Bent shank Overload during use Inspect for cracks, reprint if compromised
Sagging overhangs Insufficient support Reprint with supports enabled

4. Shoe & Shank Attachment Issues

Calf Sleeve Slipping

Cause Solution
Sleeve too loose Use smaller size or add padding
Smooth sleeve material Add silicone grip strips
Excessive sweating Use moisture-wicking liner

Lace Interface Loosening

Symptom Cause Solution
Interface shifts during walking Laces not tight enough Re-tension laces, double-knot
Laces slip through guides Worn guide edges Inspect guides, reprint if damaged
Uneven tension Improper lacing pattern Follow lacing guide in Assembly section

Discomfort or Pressure Points

Location Cause Solution
Top of foot Dorsal interface too rigid Add foam padding
Calf Shank rotation Readjust sleeve position, check alignment
Ankle Misaligned axis Verify device axis matches ankle axis

5. General Diagnostic Checklist

Before troubleshooting, verify:

  • [ ] All bolts are tightened (but not over-torqued)
  • [ ] Bearings are properly seated
  • [ ] No visible cracks or deformations
  • [ ] Gearbox rotates smoothly by hand
  • [ ] Hinge moves freely
  • [ ] Shoe interface is securely attached
  • [ ] Laces are properly tensioned
  • [ ] Motor is unpowered during inspection

See Also