Symetrix bay

Hi Tech Engineering & Construction

Symetrix hullplugThe J/121 hull plug construction was done by Symmetrix Composite Tooling in Bristol, Rhode Island.  Symmetrix is the most advanced precision tooling company in New England and is carving both the J/121 hull and deck plugs using the state-of-the-art CMS Poseidon 5-axis Machining Center located within their impressive tooling facility just a few hundred yards up the road from the CCFC factory.

This machine is like a building within a building, equivalent in size to four or five large garage bays stacked end to end with a perfectly level and polished cement floor.  The overhead computer controlled universal robotic cutter head runs down calibrated tracks on top of the side walls from one end to the other and can reach almost anywhere within the space. The large format CNC machining is optimized for durability, reliability and precision machining of advanced composite materials. It never compromises rigidity or stability over an impressively large work envelope. Further improving its overall structural stability, Poseidon’s A & C axis are equipped with a pneumatic breaking system, which locks either or both the A or C axis when their interpolated movement is not required, resulting in greater 3 axis rigidity. The CMS Machining Center at Symmetrix delivers the tight tolerance needed for aerospace, transportation, alternative energy, marine, art and architecture. In fact, the machining center was certified to an overall volumetric tolerance of 0.1mm or .004”.

X= 26m /83.3’ Y=6.2m /20.4’ Z=3m /9.9’ A= +/-120° C= +/- 270°

Symmetrix engineers analyze final 3D design models provided by J/Boats using Siemens NX11 CAD/CAM software and will run a series of simulations to arrive at final machining instructions for the 5-axis milling machine.   The Siemens NX11

software is a quantum leap forward in delivering tooling not just quickly, but also accurately. Similarly used at companies like Boeing, SpaceX, and MacDonnell Douglas, NX10 gives Symmetrix complete surface model control and simulation in either 3+2 optimized or full 5-axis machining instruction. Like Symmetrix, NX10 has been tested and used across a wide range of industries.  The combination can produce outputs even seasoned craftsmen can’t achieve. Whether it’s curved composite roof columns or the exacting requirements of an America’s Cup entrant, it can achieve tolerance within millimeters over a 26 meter surface and in a fraction of the time.

Symetrix sideThen the exciting part starts.  First the steel backbone frame with foam blocking is milled to within an inch or two of the final plug surface (all milled foam is recycled, BTW) and then the plug and foam are supported by fiberglass/epoxy reinforcement, and then an epoxy milling paste is applied over the glass.  The part returns to the milling machine for a second and final precision machining operation to take it to the final surface.  Hand sanding to 800 grit and buffing to a mirror shine then completes the effort.

From initial steel framing construction, to precision milling operations, to the final polishing the process to build a complete mirror finish hull plug/pattern will take just 7 short weeks. Production molds will then be constructed in January at CCFC and from there J/121 project development will accelerate through the winter and into spring.

By mid-December the Symettrix team completed the hull plug, with the majority of the actual CNC 5-axis machining taking place in the "rough cut" over a 2.5 day period!  Here is the amazing production video of that process, watch it here on

J121 hull CNC machining video