3D Printer Basics and Troubleshooting: FDM Printers

This Instructable is to help with understanding the basics of 3D Printing and how to troubleshoot the most common problems with FDM 3D printers. These images were taken from a slideshow that I created to help people with 3D printing.

What is a 3D Printer?

• A robot that can make 3D objects from electronic data, also called Additive Manufacturing

• Popular Types of 3D printers

–Fused Deposition Modeling (FDM)

• Extrudes molten plastic layer by layer

–Selective Laser Sintering (SLS)

• Laser melts plastic powder layer by layer

–Stereolithography

• UV light hardens liquid layer by layer

Step 1: 3D Printing Workflow

Why FDM printing?

• FDM 3D printing is popular because it is the lowest cost method for creating prototypes and refining designs at home

• FDM – Thicker parts, rougher surface finish

• Lowest Cost, fast prints

• Large parts can warp without a heated bed

• Support structures required

• Usually within 11” X 6” X 6”

• Usually weaker PLA material is used

• Walls thinner than .060” can get messy

Step 2: FDM Print Fail Issues

• Nozzle Clogging or Missing Layers

• Parts Warp or Don’t Stick to Bed

• Hole Inner Diameter (ID) is Smaller than Anticipated

• Bridges and Supports

• Multi-zone Temperature control is critical!

Zone 1 (~200 for PLA)

Filament melts and is pushed out from cool filament above

Zone 2 (~Room Temp Fan)

Filament guided in and pushes out molten plastic.

Filament buckles if too hot.

Zone 3 (~Room Temp Fan)

Filament cools to harden fast

Step 3: Nozzle Clogging

• Verify temperature zones are working within 10%

• Make sure no crust in feeder gear

• Nozzle seems to clog more when filament is low – Moisture may be absorbed toward the center of the spool

• Brand new filament, or a full roll, seems to solve this problem

• Preheat nozzle and manually push filament through to feel it go through easily, resistance should be minimal

• Measure the diameter of the output and it should be close to the nozzle diameter

• .15mm or higher layer thickness yields best results, possibly due to self-cleaning

• Output should be close to nozzle diameter. Thinner output means nozzle is still clogged

Step 4: Warping, Holes Closing Up, and Supports

Warping or Not Sticking to Bed

• Bed level is critical for first layer! – First layer should be a smear like a gluestick – Nozzle can jam if it’s too close to the bed

• Heated bed (~60°C for PLA) or painter’s tape helps

• Rafts help with sticking, but not warping

• Consider ribs for the bottom of large surfaces

• Print vertically instead of horizontally if possible

Small Holes Closing Up

• Rotation around a hole creates tension and pulls filament toward the center like a rope

• Hole ID is affected more because there is less support material underneath to stick to

• If support is insufficient, like an aggressive undercut, filament can fall off the edge

Supports

• Bridges spanning less than an inch long need no support

• Gradual radius arches or hallow shapes print fine without supports

• Simple conical supports for suspended features peel off easily

• Support material not required for all suspended geometry

Step 5: Going in to Production and Other Resources

Production

• Mold injected version is more precise, so FDM specific geometry like hole size will not translate over

• Not all 3D printed parts can be mold injected – Draft angles, wall thickness, parting lines required for mold injection – CAD software and online service like Protomold can detect issues

Where Can I 3D Print Something?

• Membership
at a shop with 3D printers

–Laserbird.org (Hackerspace, no time limits, FDM Printers)

–ADX (Must reserve time, FDM printers)

• Online Services

–Shapeways (SLS)

–i.materialise (SLS)

–Solidconcepts (SLS, Injection Molding, Machining, etc.)

–Makexyz (Find 3D printers in your area)

• Purchase a Desktop 3D Printer

–Low-end 3D printers still cost over a thousand dollars

–Only a few Low-end printers on the market are good (Purchase carefully)