Open source stereolithography (SL) equipment provides flexibility to choose the best software options for 3D printed light weighting or investment-casting projects.

In real open source, you have the right to control your own destiny-Linus Torvalds, Principal Developer of the Linux Kernel

Stereolithography (SL) open source equipment provides users with the freedom to develop improved products and process. Open sourcing also avoids investing in costly features whose function is blocking third party products, as well as offering the user a choice of world-class materials and software from established market sources. Therefore, open source equipment options continue to grow in the 3D printing marketplace.

When UnionTech set out to design and build their SL machines in 2000, all SL equipment were open sourced for materials but application software from the manufacturer was equipment specific. When UnionTech entered international markets in 2016, the value to the customer for open source options for both materials and software was evident. Open source strategy allows users to future-proof their investment in the eventuality of third party development of materials or software that either opens new applications or enhanced cost effectiveness.

The open source design of UnionTech equipment provides users the ability to incorporate software of their choosing to improve part design. One such software choice is TetraShell™ available from Materialise. TetraShell software produces hollowed wall structures with integral reinforcement for enhanced structural integrity. The level of reinforcement from the tetra-lattice structure can be adjusted by modification of leg length and or leg thickness. Drain openings can be placed by the user to accommodate drainage of even complex shapes.

UnionTech tetris

This software provides users of any industrial stereolithography printer the ability to work on projects such as light weighting and investment casting patterns.

Light Weighting

Use of SL Investment casting patterns is a well known , so this discussion will focus on the opportunities for enhanced cost effectiveness in architectural models, art installations and point-of- purchase displays. With typical SL material costs in excess of $200.00 per kg, applications that were previously closed to SL because of cost or weight considerations are now feasible.

Users obtain complete control over wall and skin thickness as well as the length and thickness of the legs. In this light-weighting example below, the TetraLattice™ connects the two walls into a single, more stable beam section, supplying greater structural integrity compared to simply hollowed parts.

One of the greatest challenges for material, equipment or software suppliers wishing to publicize application technology is finding an OEM or 3D printing service provider willing to share practical examples while protecting typically confidential designs.

Through the courtesy of the Chicago Architecture Foundation and Columbian Model and Exhibit works, the design files for the iconic Chicago Hancock building were provided for a light weighting demonstration for the 2018 Additive Manufacturer’s User Group followed by the SME RAPID & TCT exhibition. The goal was to significantly reduce material usage while maintaining structural integrity on an architectural model.

UnionTech Hancock-buildings-UnionTech-stereolithography

RP America, a major UnionTech equipment distributor, built two versions of the model using Somos® WaterClear 10122 material. One was built with solid walls (4 mm thick), and the second was built with hollowed walls reinforced with an internal lattice structure. The wall thickness of the hollowed model (1 mm) was significantly greater than typically used for investment casting, yet still designed for a 50% weight savings.

The UnionTech PILOT 450 stereolithography printer,with a fine resolution beam of approximately 100 microns, was used to print models with a 0.10 mm (0.004 in) layer thickness for smooth sidewalls and fine detail. The 450 mm square platform allowed both the TetraShell-ed and solid wall model to be built on the same platform. The height of the model, at a build scale of 1” = 50’ required each model to be built in two sections for subsequent assembly. Each model received a brief UV postcure. The TetraShell model was drained through holes placed on the bottom flange with the aid of a centrifugal device. Somos WaterClear 10122 was used for this demonstration to allow inspection of the wall structure.


Any SL material can be used for light-weighting in this fashion; however, low viscosity materials drain easier and clear materials allow inspection for drainage.

How significant are cost savings with this approach? The solid walled model weighed 0.6 kg while the TetraShell model weighed in at 0.3 kg, a 50% weight savings representing a material cost saving of greater than $60.00/kg.

The goal of this project was to produce robust models, while still demonstrating significant weight savings. Depending on structural requirements, even greater material savings are possible.

Beyond architectural models, sculptures and other art installations offer untapped potential for large format SL printers: highly detailed surface aesthetic with the ability to significantly reduce overall production cost.

UnionTech Stereolithography art and sculptureUnionTech Fox Stereolithography

This open design approach of UnionTech equipment allows OEMs and service providers to fully utilize their equipment investment to create optimal application solutions.