Bridge and Overhang Mashup

This is a print test and demo for the constraints that come from unsupported overhangs and bridges. You can print this as a demo for students to remind them of the constraints of FDM printing and design.

This is a remix of https://www.thingiverse.com/thing:2593077 and https://www.thingiverse.com/thing:40382

Print one without supports to show what happens when overhangs are greater than 45 degrees. Print a second with supports from the build plate to show the difference supports can make.

Make sure to emphasizes that supports will leave a rough surface, and cost more time and materials. If you have a dual extruder, you can show how water-soluble supports work. Orient the overhang side to face the cooling fans on your specific printer for best results.

I hacked them together in TinkerCAD.

Print instructions

Category: 3D Printing Tests Print Settings

Printer Brand: LulzBot

Printer: TAZ 5

Rafts: Doesn't Matter

Supports: No

Resolution: 0.3 - 0.3

Notes:

Leave rough, do not sand or process.

Post-Printing

Leave rough to show unsupported overhangs and bridges

How I Designed This

This is a TinkerCAD hack

Overview and Background

Demo

When you have your students design items for 3D printing, use this to show them the constraints that come from unsupported overhangs and bridges.

Show them that they can have overhangs to 45 degrees before the surface quality decreases. Show that bridges can go only so far before the filament strands sag.

Print one unsupported, and the 2d supported from the build plate. You can also print with a brim / skirt and raft to also show the different types of build plate support.

You can time laps the printing to show the constraints and what happens when your overhang is not supported past 45 degrees, or bridge goes past 10 mm. This can be a demo piece to match the 3D printing handbook published by 3DHubs.

Lesson Plan and Activity

Print 2-4 samples, and pass around to show how print quality degrades with steep overhangs and long bridges.

Skills Learned

• supports
• bridging
• overhang
• restrictions

• constraints

  Preparation

  Print 2-4 sets per class to be passed around. Do not clean or process the print, leave all loose strings and rough edges on this to show what happens with steep overhangs and long bridges.