Erasmus bridge tutorial

Contributed by
Jacky Wan

Architectural visualization is one of the most fitting uses for 3D printing. Traditionally, scale models would be created from laser cut cardstock, foam core or wood, then painstakingly glued together by artists. This method is costly and time-consuming while producing fragile models. With 3D printing, that process can be streamlined and production times shortened by reusing the visualization models made by the architects and printing the complex structures. Not only is it faster but it is also much more accurate, durable and cost effective. This guide will walk you through printing and assembly of the iconic Erasmus bridge on the Ultimaker 2 Extended+!

The Erasmus bridge is a combined cable-stayed and bascule bridge in the center of Rotterdam, the Netherlands. Because of its distinctive and elegant shape the inhabitants of Rotterdam have nicknamed the bridge, designed by Ben van Berkel, 'The Swan'. After the bridge was completed in 1996 it soon became the signature piece of the city's architecture and a defining part of the skyline.

Erasmus bridge by night
Image by lukeprice88 (CC:BY2.0)

Design Considerations

The bridge is quite long overall, much wider than the build plate of the printer so the road portion of the bridge will need to be split into multiple pieces and connected together. We will use thin nylon thread as the bridge cables. Tiny holes are designed into the model so that placement of the cables will be quick and painless with no drilling required. This is important both for the speed of assembly and ensuring the proper spacing of the wires.

What you need

Start by downloading the model files free here on YouMagine. You will also need some additional tools for the build. You will need: Nylon thread (or similar) and a hot glue gun (optional: flush cutters, pin vise, tweezers, pliers).

Tools for assembling the Erasmus bridge

Recommended settings

This is a fairly easy print requiring no special settings. Supports will be required for the main bridge structure. Meticulous bed leveling will translate directly into a smoother surface finish on the road surface.

Erasmus bridge close-up

These are the settings we chose to print with. It is a good place to start but not the only way. It is an easy print so you can use whatever settings you like and it will likely print well. You can print the model in 3 plates:

Buildplate 1

1x Bridge_Road_01

4x Bridge_Pin_x4

Buildplate 2

1x Bridge_Road_02

1x Bridge_Road_03

Buildplate 3

1x Bridge_structure

Bridge structure

Quality
Layer height0.09
Shell thickness0.8
Nozzle size0.4
Fill
Bottom/top thickness0.8
Fill density20%
Speed and Temperature
Print speed35
SupportBuildplate (lines)
Platform adhesionBrim
Quality
Initial layer thickness0
Initial layer line width100
Speed
Travel speed170
Bottom layer speed15
Infill speed0
Top/bottom speed0
Outer shell speed0
Inner shell speed0
Minimum layer time10

Road pieces

Quality
Layer height0.12
Shell thickness0.8
Nozzle size0.4
Fill
Bottom/top thickness0.8
Fill density20%
Speed and Temperature
Print speed45
SupportNone
Platform adhesionNone
Quality
Initial layer thickness0
Initial layer line width100
Speed
Travel speed170
Bottom layer speed15
Infill speed0
Top/bottom speed0
Outer shell speed0
Inner shell speed0
Minimum layer time10

Material

Ultimaker PLA White was used in this model. We chose PLA because it retains nice sharp edges, prints well and requires no glue for a heated glass bed. This allows us to print the roads upside down and achieve a very smooth shiny surface for presentation. We will also be using straight, unused filament for the rear bridge supports.

Ultimaker PLA white

Cleanup

When you have printed your pieces, begin by removing the supports from the main bridge structure with pliers. Using the 'line' style of support allows for easier removal. File or sand the underside after the supports have been removed if required. Remove the brim.

Cleaning up 3D print
Cleaning up 3D print

Use a pin vice or awl to clean the holes. A burr will make it difficult to insert the nylon thread so be sure to clean up the holes and edges as best you can.

Assembly

Insert pins into bridge road
Begin assembly by inserting the pins into the road slots and then attaching the 3 pieces of bridge together to form one large bridge. The longest piece of the bridge with no holes sits on the bridge structure. The end with holes gets suspended.
Flip bridge structure
Set the road aside for now and flip the bridge structure upside down as shown so you can easily work on the cable slots. Cut 32 lengths of 45cm (18”) nylon thread.

Hot glue nylon thread
Insert the ends of the nylon thread into the printed grooves and, using the hot glue gun, secure them in place with a small dab of glue. Don’t hold the glue gun on the print too long or you may deform the PLA print.
Seat road into bridge
After each thread is secured into place, seat the road portion of the bridge onto the structure and tape it into place.

Insert thread into bridge road
Carefully insert the thread into the holes starting from highest thread on the bridge structure to the outermost hole on the bridge, working your way towards the center. Pull the thread tight with tweezers.
Hot glue seal holes
Once all the thread is strung through, flip the bridge on its side, and seal the hole with hot glue. Hold the thread tight for a few seconds as the glue cools.

Snip excess nylon thread
Once all the strings are in place you can tighten them up by heating the glue with the glue gun (without applying more glue) and pulling on the thread. Snip the excess thread when complete.
Cut and straighten filament
At this point you may want to glue the bridge in place as well, so it doesn’t move when you remove the tape. Snip an 8 inch (20.3cm) piece of filament off the roll and straighten it out as best you can to create rods.

Insert filament in support grooves
Insert the filament rods into the support grooves. This should require no glue if the length is correct.
3D Printed Erasmus bridge
Congratulations! You’re now finished your 3D printed model of the Erasmus bridge!

Don't forget to show your print off in our 3D print section. And if you have any questions or comments about this model or the guide, please tell us on the Ultimaker community forum!

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