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This page presents the assignments for week 16 of Fab Academy 2020: “Wildcard Week”.

To do list:


Week 16 CAD files:

composite.scad (own work)

laser_cut_parts.scad (own work)

Week 16 "hero shot":

Figure 0: Epoxy and Burlap landing gear with shock absorbers

Table of Contents

Individual assignment

This week I wanted to make a "skate" lower part for the landing gear of my drone, using burlap and epoxy.


This lower part should


I used openSCAD to make the design of the skate landing gear.

I used balsa wood and 3D printed connectors inside the burlap and epoxy composite. The 3D printed connectors are secured to the upper part of the landing gear with screws and nuts.

The balsa board allows to maintain the 3D printed parts at their designated locations.

Balsa board with live hinge

3D printed connectors

Balsa board and 3D printed connectors

Burlap top

Burlap bellow

3D printed connectors

3D printed connector

4 3D printed per skate

Laser cutting

The balsa board

I used the laser cutter to

First, test live hinge on a small balsa part

Then laser cut the balsa board

Balsa board with 3D printed connector inside
As we want the skate to be easily removable, the orientation of the 3D connectors matters.

We want the hole for the nut to point toward the interior of the skate.

It will allow to easily screw and unscrew from the outside.

The burlap

I used the laser cutter to cut the exact pattern to fit on the balsa board.

First, cut manually some burlap from the stock.

The burlap is not flat, even with weights

Quick hack, use a cardboard with pins under the burlap

Work like a charm

Burlap fitted on the skate

Applying epoxy to the balsa board and burlap

Epoxy Resin Greenpoxy 56 + Hardener SD Surf Clear

The safety data sheet of Epoxy Resin Greenpoxy 56 and Hardener SD Surf Clear from Sicomin (French producer) are available to download on their webpage (here).

Epoxy Resin Greenpoxy 56 is hazardous for the environment (aquatic) as shown in the figures bellow.

Epoxy Resin Greenpoxy 56 hazards (French)

Epoxy Resin Greenpoxy 56 hazards (French)
It also has a moderate risk of irritation of the skin,eyes and lung.

Hardener SD Surf Clear is very hazardous for the lung, eyes as shown in the figures bellow.

Hardener SD Surf Clear hazards (French)

Hardener SD Surf Clear hazards (French)

I used the fume hood of the Lab, a mask and gloves to make the mixture and pourring.

Setting up

Setting up under the fume hood

Using weights to curve the live hinges
As the epoxy components are hazardous, I make the epoxy coating under the fume hood of the Bio Lab using glooves a mask and glasses.


First the balsa board top with the 3D connectors inside are painted with one layer of epoxy.

Then the cutted burlap is fitted on top.

One final layer of epoxy is then added to the burlap.

Coating balsa board rear

Coating balsa board with burlap rear

Coating balsa board middle

Pushing excess of epoxy out

Cure setting
I didn’t used compaction in all the surface of the skates, because I lakced time to design and produce approtriate weights to fit on the skate.