Additive Manufacturing Technology

Periodically, along comes a technology that takes the bicycle industry by storm. Think back to not that long ago, 3 years ago to be precise, when Di2 electronic gear shifting landed.

It was probably one of the biggest innovations since the incarnation of carbon fibre frames. Even the advent of CNC machining had the bike industry in a whirl, allowing the mass production of precision parts as beautiful as hand crafted metalwork.

However, as with all technologies there’s always an element of ‘to be expected’ as there is generally a trickle-down effect from the serious research and design players in the Defence, Aerospace or Formula-1 sectors. Then along came 3D printing, Additive Manufacturing to call it by its technical name. 

Printed Garmin mounts

The actual process has been used for a couple of decades, translating computer generated 3D models into tangible nylon parts is a quick and inexpensively way to verify a design. But with little structural integrity, it’s been mainly used just for rapid prototyping. That is – Until now.

Mettle for metal
Now with the technology constantly maturing, the boffins within the 3D printing world have developed the printing of metals; yes metal. The ability now exists to ‘print’ structurally sound three-dimensional parts in a range of metallic alloys including a variety of aluminium, stainless steel and titanium alloys. It’s, quite frankly, radical.

Accessibility of the manufacturing, without the need for specialist tooling, minimum runs or costly moulding, has opened up a massive window of opportunity to viably create innovative and bespoke componentry for the bicycle. There is little material waste, and with the ability to produce wall thicknesses down to 1mm.

Printing under way: laser melts metallic ‘dust’

Complex latticework, hollow structures and even moving parts can be constructed in a single process. Compared to CNC machining where a specialist tools are required and a solid piece of metal has sections removed, 3D printed structures are constructed from the ground up.

This means lighter, cheaper and, quite possibly, stronger is now obtainable: the ultimate goal in bicycle manufacturing. The ability to take a fresh look at the existing elements of a bike is potentially where the future ‘marginal gains’ will come from.

Various internal 3D structures available

How does it work?
Once a conceptual 3D shape has been modelled using a CAD system (Computer Aided Design). The ‘printing’ software slices the object up. A laser then automatically draws this slice over a layer of pre-heated additive powder. As the laser comes into contact with the powder it melts the powder forming forms a solid piece.

A new layer of powder is laid down and the next slice of the pattern is traced out. And so it continues until the end result is an exact replication of the CAD model. This means even moving parts can now be manufactured in a single process.

Printed yet flexible

Cycling Products
One of the reasons this technology is becoming noticed within the cycling industry is that there is a keen cyclist at the heart of one of the UK based industry-leading companies. 3T RPD Ltd Project Manager, Martyn Harris felt that the technology he believes in, and works with everyday, had application in the hobby that takes up his spare time.

The Garmin mount has taken several design iterations before settling on a final production design. The design is then simply printed from the CAD file, with no material or production penalty, ‘runs’ can be a minimum of one and – after a quick CAD update – completely personalised. From the simple first idea – and the CAD design work done via a contact from a cycling forum, the range is constantly expanding. SRM mounts are currently being tested to allow fitting to TT bars, and seatposts for track use.

Over 800 colours

3T RPD Ltd
Since being established in 1999 3T RPD Ltd has been busy ‘printing’ in three dimensions. It’s currently the leading Additive Manufacturer in the UK, with 50% of the plastic and 40% of the metal printing market. It’s actively working with a variety of sectors from automotive, in the construction of gearbox elements, to aeronautical, in the redevelopment of the traditional seatbelt buckle – saving considerable aircraft weight and therefore aviation fuel – the details of this particular project can be found on the Savings Project website

UK brand Charge is well known for not being afraid of new things. It’s fair to say they were the first mainstream bike company to produce track bikes for general sale that were based on those being used by the urban hipsters.

It’s not just visual trends however, as the dropouts on their 2013 cyclo-cross frame prove. Being based in bath, they have worked in conjunction with Bristol based AEDS to develop a dropout assembly for their disc brake titanium frame that utilises additive manufacturing.

When a niche product such a disc brake cross frame first comes to market, ancillary components available to manufacturers are few and far between. When it’s a niche of a niche – like a Ti disc specific cross frame – the options dwindle further. Rather than ruin the looks of a top end product with off the shelf components, Charge had to go another route.

They wanted to make a lightweight part to match the performance of the frame, but also one that maintained the brand aesthetic. His is where the 3D printing construction methods come in. As we have talked about, the adaptive manufacturing process has developed from plastic alone to metallic elements.

Cross-section of the prototype

The ability to print metals means structures completely impossible to make via other methods (forging, stamping, machining or a combination of them) can be conceived and manufactured without doing any more design work than Cad and FEA. There are no costly moulds to produce, or expensive tooling to pay for up front. With a small-scale model such as the xxx, such costs would prevent the bike being possible due to prohibitive costs.

The final dropouts comprise of an arcing tubular construction, entirely hollow but with internal reinforcing elements to cope with the stresses the disc brakes place on them. The fact that the brand identity can be incorporated to the already classy looking construction is simply icing on the cake.

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The Future: A 3T-RPD and SmartAero collaboration

The working relationship between Simon Smart (renowned cycling aerodynamicist  behind the design of Enve Wheels, Giants Trinity, Scott’s Foil and other aero bike designs as well as wind tunnel positioning guru) and 3T-RPD has been ongoing with the company producing the prototype shapes for early wind tunnel testing on many of SmartAero’s projects but this project has been a more collaborative effort.

With Smart unhappy with the current offerings available for cockpit design when it comes to aerodynamics, brainstorming sessions developed into the project to produce a stem using addative manufacturing. Using the knowledge gained working on the Saving Project along with in house programs in other fields, 3t-RPD’s Harris and Smart worked out how to use the variable internal 3d grid structures to provide structural integrity to the stem while minimising any excess material.

With Titanium chosen as the material, the project is an ongoing development where, based on the FEA (Finite Element Analysis – a computer program to study the forces on a component in a virtual world), the density, size and scale of the internal structures can be varied almost infinitely.

Printed yet moving

The beauty of this construction method is that this variance is impossible to produce in any other way. It also allows the external shape to have no relevance to the structural integrity of a component making the collaboration a perfect match between the external requirements of an aerodynamicist and the integrity required by a structural engineer.

We spoke with Smart at Eurobike where he had just had the project confirmed as a future product to be produced by Enve Composites. With their backing, the stem is more likely to be a commercially viable product and the aerodynamic fairings to the rear are likely to comprise of the Americans specialist subject – carbon fibre. Due to the construction method, the length and drop are all completely customisable with no tooling costs.

First: plastic prototypes

A few tweaks to the CAD file and the new stem dimensions allow for any number of unique stems to be produced at the same time. Quite literally the possibilities are endless, and this is why this construction method has many people within the cycle industry very excited indeed!

This article was first published in the September 6 issue of Cycling Weekly. You can also read our magazines on Zinio and download from the Apple store.