'Unbreakable' Bike Custom-Crafted

In 2013, Thunderbike presented its “Unbreakable” custom project for the first time at the European BikeWeek at Lake Faaker in Austria, the largest Harley get-together in Europe

The cruiser, made from turned and milled components, brought home three titles. The custom parts were machined in-house on modern five-axis machining centers with TNC controls from Heidenhein.

Using Heidenhain controls, Thunderbike created a unique motorbike with an extremely low seat position and sweeping Art Déco-style curves.

Thunderbike uses original Harley Davidson parts for the complete drive components and electronics, but all other parts are produced in-house. The self-constructed, milled parts are a particular Thunderbike specialty: fork bridges, turn signals, wheels, radiator grills, stops, hand grips, gas caps and seats are all milled in the company’s workshop, sometimes with highly stylish ornamentation.

The engine and gearbox covers are produced to match the other components and feature the typical parallel ribs.

The Planning Stages

Scribbles and technical drawings are used to integrate the customer’s ideas into the concept phase. Thunderbike places its trust in hyperCAD and hyperMILL for CAD/CAM implementation, and has created a sector-pioneering process chain that includes machines equipped with Heidenhain controls.

All components are modeled and constructed in the CAD system and receive their unique look during this phase, with the complete project expanding in a virtual kit of components where appearance, fitting accuracy and assembly capability are ideally matched and assessed.

hyperCAD is simultaneously used in supplementary areas for machining and vendor parts.

“With hyperCAD we’re simply more flexible, especially with free-formed surfaces when nearing actual production,” said Herbert Niehues, responsible for the planning and production of components.

Graphic simulation of the machining cycles is highly important, because with turning/milling using five-axis technology, the DCM (dynamic collision monitoring) function provides the necessary safety to run the planned cycles on the machine. The ideal interplay between the CAM system and the Heidenhain TNC 640 control is the result of a close cooperation between both manufacturers.

“Precision of the faces is very high because the new control and the machine are able to implement the tighter points defined in the CAM system,” Niehues said.

Workshop-Oriented Control Technology

The complete CNC machine park for milling and turning is equipped with Heidenhain controls. The highlight is the new turning-milling center with a TNC 640 control.

“Heidenhain has even further improved machining performance with the TNC 640,” said Niehues.

“We’re really keen on the new user guidance, and we consistently receive updates. The large package of turning cycles, constant cutting speed and tool-tip radius compensation are certainly significant benefits of the control.”

From Design to Application

One example of those benefits can be seen in the newly designed wheels of the Unbreakable – a 26 inch diameter at the front and 21 inches at the back, with their inner free-form areas being reminiscent of turbine blades.

These aesthetic highlights are initially machined on the new turning-milling center from an aluminum block at a maximum speed of 800 revolutions per minute. The contours are then produced with five-axis simultaneous milling.

“For us this means less rechucking as well as shorter equipping and idle times,” said Niehues. The previous six work cycles on three different machines were reduced to just three work cycles in the turning-milling center.

Following initial milling, the wheels are anodized by an external company, then fixed on the machine again for milling the outer edges and creating the metallic contrast to the matte coating.

The TNC 640 once again provides the right strategy for this task—with five-axis contour milling the tool is always inclined at the same angle to the face, ensuring that the width of the milling path remains constant.

With its all-milled parts, the Unbreakable is an example of ideal implementation of Heidenhain control technology to create a show-stopping bike.