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The Utrecht city chess set

Iconic figures from the city's history as chess pieces.

A large size chess set has been created for The Utrecht Archives. These Archives collect the sources of Utrecht’s long history, with the aim of making them publicly available. The chess set perfectly fits this aim, as it features historic figures and is available for the public (in the Expo department of the Archives). The set has been financed by a successful crowd-funding project.

We were very excited to hear about this, as this is a DeskProto project in our own home town !

The complete chess set, in the city's colors red and white.
The complete chess set.

DeskProto user Jules Dock Shaping (website in Dutch) specializes in large size complex shapes, so this project perfectly fitted their expertise. Their large size CNC machine (working area 5 x 2 x 1 meter) and their DeskProto software, combined with their experience and know-how, proved to be perfect tools for the job.

Dom tower as chess king
Woman with axe as chess queen
Catholic pope as chess bishop
The King, Queen and Bishop of this Utrecht chess set.

The pieces in this chess set are iconic figures from the long history of Utrecht;
  • King - The Dom church tower. This is the tallest medieval tower in the Netherlands (112.3 m), Utrecht's main city landmark.
  • Queen - Trijn van Leemput. In 1577 she lead a large group of woman from Utrecht to start demolishing the Vredenburg: the citadel used to oppress the population.
  • Rook (tower) - Water tower Heuveloord (1907, 37 m tall). One of the three old water towers in Utrecht (no longer in use as water tower).
  • Bishop - Pope Adrian VI. So far the only Dutchman ever appointed as pope (1521), born in Utrecht as Adriaan Florenszoon Boeyens, son of a carpenter.
  • Knight - St Martin, the city's patron saint. He was a Roman soldier who on a cold day used his sword to cut his own cloak, to give one half to a beggar at the city gate.
  • Pawn - Miffy (in Dutch Nijntje), the world-famous character, born in 1955, by Utrecht citizen Dick Bruna. In Utrecht you can visit the Nijntje museum.
The chess pieces are colored red and white: the Utrecht city colors, after the red cloak and white undergarment of St Martin.

DeskProto screenshot showing the queen and the bshop, to be machines as halves.
The queen and the bishop in DeskProto, positioned and oriented to calculate toolpaths.

For some of the pieces the fabrication process was easy: simply machine two halves and glue them together to form one complete piece. This could for instance be done for the bishop (shown on the DeskProto screenshot above) and for Miffy.

Other pieces were more complicated and needed to be constructed from more than two parts, with parts that needed to be machined from several sides. Like the queen: the screenshot above shows the main body, the arms will be done as separate parts.

block of wood with contour-only toolpaths
The first toolpaths for the bishop, in solid Abachi.

The pieces have been machined in solid Abachi wood. Jules Dock first applies a series of contour-only toolpaths: after that operation a large part of the block can be removed. That minimizes machining time, and makes sure that the chips can easily fall off.

For the Dom tower and the water tower it would have been possible to use a rotation axis, however Jules Dock used the alternative method: three-axis machining from several sides, keeping the part in place using support tabs.

freshly machined parts on the machine.
Parts for the queen and the bishop, just after machining.

In the image above, just after machining, the halves for the bishop and for the queen can clearly be recognized. The bishop will be ready after assembling both haves. For the queen more work will be needed (as is of course appropriate for a queen): both arms (one of them holding an axe) were machined as separate parts. The block with the arms has been machined from two sides, the parts remained connected to the block using support tabs.

CAD-model of the queen
CAD-model of the queen's arms
The arms just after machining
CAD-data for the complete queen and next for her arms as separate parts, with right the arms after machining from one side.

After assembly of the pieces (using glue) some manual work was of course needed to fill and smoothen all seams. And a few areas where the cutter could not reach have been detailed by hand using a small Dremel tool.
Most of the work has been done by the machine though: using a small cutter and accepting the resulting long machining times. As the machine can be kept running 24 hours a day these machining times were not a problem for Jules Dock.
Final step was painting: one series in white, one series in red.

The chess set being used for a game
The first chess game, at the set's unveiling.   (photo by Bas van Setten)

The set has been unveiled in July 2020, when initiator André van Schie and city poet Ingmar Heytze played the first game, in front of the Expo building.

The resulting chess set now can be found in the Expo of the Utrecht Archives, where you can use it to play a game of chess.

Some red chess pieces in closer view
Detail of the previous photo, zoomed in on the six different pieces of the red side.

The names that you see are the names of the crowd-funding sponsors: it was possible to sponsor one of the chess pieces or one of the 64 squares in the chessboard.

The Utrecht Archives have started the project to create this large size chess set because all six iconic figures and their stories play an important role in the new permanent exposition at the Archives Expo.