This is a 3D printed version of the very popular Kontax KS90 Low Temperature differential Stirling Engine. Back in the early 2000s I designed what was the first commercially available Low Temperature Stirling engine, the Kontax KS90. Over the years it has proven very popular with enthusiasts with many, many thousands being sold.

With the development of accurate and reliable 3D printers I decided to develop a 3D printed version of the KS90 and this is the result, a small kit of pre-machined parts and 3 3D printed parts.

Stirling Engines are a type of heat engine that rely on an external temperature difference for operation. The most obvious source of a temperature differential in the case of a 3D printed Stirling Engine is the print bed the engine was printed on. Once you have assembled your engine you can heat your bed to 30 degrees above ambient and run your engine directly on the bed.

To make an engine you will need to purchase the kit of parts and print a Base, Top, and Spokes. Depending on how well your Spokes come out you may need to print a Spokes Tool.

Gcode files, 3mf files and individual stl files are all provided for full flexibility. The stl files have split lines so you can split to parts for easy colour changing with an MMU. With the Spokes there is a split between the curved spokes and the rim to allow for the whole rim to be a different colour to the spokes. If you don't have an MMU you can of course trigger a colour change after layer 14 on all 3 parts. With the recommended layer height of 0.2mm this will give the appearance of different materials for the different parts of the engine (see photos). PLA is best for rigidity.

ENGINE FEATURES

• Stainless steel screws
• Micron precision Borosilicate glass cylinder and Graphite power piston
• Ultra low friction demagnetised and de-greased bearings, NO lubrication required
• Both connecting rods are positively located using low friction PEEK and stainless steel screws
• Airtight seals made with a custom gasket and nitrile O rings
• Your choice of colours (pick the 3D filament colour)
• Chrome steel balls used to weight flywheel
• We provide the files for you to 3D print remaining parts

MATERIALS

• Ball-race bearings
• Micron precision Borosilicate glass cylinder
• Micron precision Graphite power piston
• Light weight displacer
• Chrome steel flywheel weights

PARTS supplied

• Hub
• Axle
• Gland
• Gland stem
• Crank
• Piston
• Piston insert
• Conrod bush
• Displacer
• Displacer clip short
• Displacer clip long
• Glass for power cylinder
• Con-rod
• All screws
• O rings for creating airtight seal
• Custom made Neoprene gasket
• Chrome steel balls to add weight to flywheel
• Precision ball bearings