Increasing the capacity and capability of its machine shop with two new machining centres will ensure that Tom Dark Engineering Ltd maintains its leading role in the highly competitive field of restoring classic cars.
The company offers the owners of vintage racing cars and touring cars a comprehensive range of services, from the manufacture of a single component for a rare historic vehicle to a complete marque replica capable of full-race competition.
Founder and managing director Tom Dark says: “Some of the replica’s we create are of high-value legendary cars from the likes of Maserati, Bugatti and MG. Our reputation has been built on being able to re-create anything from an obsolete suspension component to a complete road-ready car.
"To do that, we need the appropriate manufacturing support infrastructure, so we have invested in the type of machine tools that allow us to be as self-sufficient as possible.”
Tom Dark’s machine shop and assembly plant are located in a converted barn near Kiddington, Oxfordshire, in the heartland of the UK motor-sport industry. Very often, the company is tasked with manufacturing components without any drawings — a process that involves creating a tool-room copy, extensive pattern work for castings and the use of 3-D and solid modelling.
The raw materials used are also varied; bronze, aluminium and cast iron are commonplace, but EN24 and EN36 alloys are used for tight-tolerance highly stressed components.
“We have a mixed workshop capability, but we were very careful when specifying the two latest machines. We had to ensure that they gave us the optimum capacity, coupled with the precision, capability and reliability that are essential in our business.”
The machines in question — supplied by Southam-based Engineering Technology Group (
www.engtechgroup.com) — are a new Bridgeport XR 760 VMC and a large-capacity Bridgeport GX 1600 VMC. They both give Tom Dark the ability to machine large components, such as a complete cylinder block casting, plus the plethora of small components that make up a car or sub assembly.
The XR 760, which is equipped with a Heidenhain iTNC530 control and has a maximum spindle speed of 12,000rev/min, features a 30-tool magazine capacity. Moreover, like all Bridgeport machines, it is equipped as standard with a Weiss spindle featuring the BIG-Plus dual-contact tool interface; it also offers high levels of rigidity and thermal stability. The machine supplied to Tom Dark was pre-wired for both probing and a fourth axis (for when the company installs a Nikken fourth-axis unit).
The GX 1600 VMC is currently the largest-capacity Hardinge VMC; it was specified because Tom Dark needs to machine complete engine castings, which are sometimes 1.4m long. This machine is also equipped with a Heidenhain iTNC530 control, has a 30-tool BT40 ATC, a 10,000rev/min spindle and a fourth-axis interface. Furthermore, to ensure that it could machine cylinder blocks and other large components, Tom Dark specified a 260mm Z-axis riser block, to optimise the machine’s height capacity.
“An in-house cylinder block machining capability is important to us; and because we also machine the pistons and the cam shafts, we have complete process control. We have also machined cylinder blocks from billets, not castings; for example, the engine for a Bugatti Type 50B entailed some 6,000hr of machining and building.
“The Bridgeport machines are undoubtedly the cornerstone of our manufacturing operations. In the past, we have operated a range of Bridgeports — VMC 800, 600XP and 1000XP — so we are long-standing users of these machines, and they stood us in good stead.”