Developing in-house capability for 3D-printing custom collimators
26 May 2026 - Rosie de Laune
An international partnership is enabling STFC to develop the skills and equipment needed to extrude unusual filaments and use them to custom 3D-print collimators for ISIS instruments.
“We’re making filaments you can’t buy and using them to 3D print components that are very difficult to make,” explains Joel Hodder from STFC’s Technology department. “We plan to use this process to build collimators for new ISIS instruments and, once established, have a quick turnaround time for making replacement parts.”
Joel is working with Rafael Heeb, a postdoctoral researcher joint between ISIS and the Paul Scherrer Institut (PSI). The project, and Rafael’s fellowship, is funded by the ISIS-Diamond-PSI award from the UK International Science Partnerships Fund (ISPF). As part of the project, has spent time at both PSI and ISIS, sharing expertise to inform the development of this new equipment.
Currently it’s not possible to 3D print the complex shapes and patterns of the ISIS neutron collimators, made of boron carbide or gadolinium oxide, and so an epoxy resin production method is used instead. However, 3D printing would be safer and easier, as well as having a quicker turnaround time for new components. 3D printers use filaments, which are heated and then used to make custom shapes. Commercial boron carbide filament is expensive and not very high quality, and it’s not possible to buy gadolinium oxide filament at all. Therefore, this project aims to develop the skills and equipment to do everything in house at STFC.
We’re making filaments you can’t buy and using them to 3D print components that are very difficult to make. We plan to use this process to build collimators for new ISIS instruments and, once established, have a quick turnaround time for making replacement parts.
Joel Hodder, STFC's Technology department
The process begins with polymer granules to which the aim is to add as much boron / gadolinium oxide as possible. These are melted and then extruded to produce a filament. It’s a balance as, the more boron that is added, the purer the finished components, but the more brittle the filament and the harder it is to handle and feed into the printer. Joel and Rafael have been testing different polymers, additives and concentrations to determine the optimal conditions.
“We have produced filament reliably at 40% boron content, but going up to 50 – 60% the filament is too brittle and difficult to load onto the reels that load the printers,” says Joel.
To make the filament, the polymer/boron granule mix is loaded by hand (currently using a catering spoon as this allows for fine control required to feed into the extruder consistently!), melted and mixed, and then guided along the cooling bath, again by hand. Along the way, the filament passes through an air knife to remove water, then through a laser to check its thickness and ovality, before being spooled on the reel. The whole filament line is twelve metres long: it needs that distance to sufficiently cool the filament and to maintain the perfect shape after it is spooled onto a reel.
Rafael has used this process to 3D print prototype collimators for the IMAT instrument, but the big goal for this project is the collimator for the HRPD-X beamline, being built as part of the Endeavour programme and due to be assembled during 2027. As well as the challenge of producing the filament, Joel has also needed to design specific software for the printer to create a custom build route for it to take to reduce errors and defects.
The HRPD-X collimator will be large, complex, and made of the rare isotope boron-10, so it’s important for them to be confident in the extrusion and printing process before the final build. They plan to print the collimator in about 40 sections to reduce the impact of any errors or breakages.
“Rafael’s expertise has been crucial throughout process,” adds Joel. “From making the filament to developing computer models to optimise the structural properties of the material. The funding has also enabled us to buy new printers. Because of the abrasiveness of boron carbide, it can be quite destructive to the machines.”
They are also using the extruder to produce gadolinium oxide filament, which will be used to produce test pieces of collimator for WISH-II, another instrument being built as part of the Endeavour Programme.
