VB Manufacturing, Phoenix House, Tern Hill, Market Drayton, Shropshire, TF9 3PX
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  +44 (0)1630 637375                          +44 (0)1630 637377                          sales@hegner.co.uk

Insights from the designer
             -Nigel Voisey explains the VB concept:

    As a woodworking journalist through the late sixties and on into the nineties, it was not my way to look for faults and shortcomings in the machines I was assigned to review, but simply to report honestly on what I found. I always hoped to find the best but was disappointed that so many manufacturers knew surprisingly little about how the machines they made were actually used.
     I came into woodworking from an engineering background and often made suggestions as to ways in whch machines I found fault with could be improved. More and more of my time was spent in original design work for various manufacturers. The main problem was that manufacturing costs placed severe constraints on the choices that could be made. Market forces dictated that "ideal" solutions rarely saw the light of day, that is, if such changes made machines considerably more expensive than outwardly similar competitors. By and large, the woodworking world at user level is too thinly spread for news of product limitations to become shared knowledge. When a newcomer to woodturning experiences problems with a particular cut, he more likely to blame himself than to recognise the limitations of the equipment he is using.
    I had settled for the fact that I was not going to find a way of removing accountants from the design loop or changing the world when Roger Buse asked me to design a lathe that I would be truly happy with. Whatever the final cost turned out to be, we would adjust our market expectations on the basis of that figure rather than design with an initial, choice-limiting cost in mind. I was delighted!
    By the mid eighties I think I had used every lathe available on the world market. None of them, not one, offered more than a basic means to make the wood go round. I still find it incredible that until very recently the most popular lathe for top woodturners had just four speeds which had to be changed, more or less blind, through a hatch at ankle level in the pedestal whilst, at the same time, supporting the weight of the motor!

NO NOISE, NO WEAR, NO "FLOAT"

    Another limitation imposed by cost considerations in the above case  (and with most other lathe designs) is seen in the choice of bearings. Although transmuted into a virtue by marketing men, ball bearings are not the ideal support for heavily loaded shafts running at low speeds. Radial ball bearing assemblies and, to a lesser extent, roller bearings, are specified for reasons of economy as they are relatively cheap to buy and demand far less rigid engineering tolerances in the machining of the housings in which they are fitted than precision plain bearings. However, where extreme load carrying capability is called for, especially at low rotational speeds, plain bearings are the natural choice because they effectively eliminate metal-to-metal contact at the bearing interface. Such bearings often have the capacity to carry loads far in excess of the actual machine frame strength. (The Rolls Royce RB211 turbine developing 38,000 shaft horse power has plain mainshaft bearings lubricated by compressed air. Industrial machines from watchmaker's lathes to micron accurate CNC grinders also use plain bearings.)

ACCESSIBLE CONTROLS

    Being able to work freely from the front, side or back of a workpiece that might measure anything up to 7' 6" in diameter (over 2 metres) highlights another essential requirement — that controls should always be comfortably to hand, or foot, when ON/OFF functions are needed.  Obviously fixed location controls cannot meet this need. VB controls are accordingly fed through a 24volt spur lead to a magnetically backed box that can be stuck on any flat metal surface precisely where needed. Switches are provided for starting and stopping the lathe; running in forward or reverse (useful for sanding, applying sealers and polishing); choosing fast or slow acceleration and braking times; and setting or varying the speed by means of a ten revolution dial. (Changing the speed over such a high number

SMOOTHEST POWER DELIVERY

    One of the problems encountered by those who first tried to give that lathe mentioned previously (the one with the ankle level belt change) electronic variable speed was that the belt slipped at low motor speed settings. A drive pulley diameter that has been calculated to transmit the full motor power at normal motor speed (say 1425rpm) loses transmissive efficiency as the motor speed is reduced. The motor will keep turning but the belt will slip. For variable speed lathes, the drive pulley diameters must be re-calculated in line with a formula that describes exactly how much power each rib of a belt will transmit at the lowest envisaged motor speed, andaccordingly by how much the drive pulley diameters need to be increased.   
    Adoption of this principal in the VB design involved a major cost that it would obviously have been much cheaper to compromise — but this would have been to negate the whole point of what we set out to do. The low speedratio of the VB's three pulley steps is therefore driven through a fifteen rib, 60mm diameter pulley. To achieve the desired 4:1 reduction  for best gearing(and to keep the motor turning at a healthy speed when the lowest setting is used ), the final drive pulley had to be machined to 240mm diameter. This is about twice the diameter and three times the width of the comparable pulley on any other proprietary

Secure "bayonet receiver" for VB fittings

Thread adaptor for other fittings

support that is required — for example when the tool needs to be supported close to its tip whilst up to 1 metredeep inside a hollow form. All of these situations are catered for within the VB system.

Conventional 'T' pattern toolrest

The XDHR Deep Hollowing Rest

   Because of its exceptionally precise turning characteristics, theVB is unmatched in its ability to allow the turner to produce the most delicate forms entirely free from the limiting effects of vibration or unwanted shaft float.
    At the other end of the scale, the VB brings you virtually unlimited potential for handling the heaviest of eccentrically shaped pieces. This is partly due to the mainshaft design and bearing configuration that I mentioned earlier. The VB's mainshaft is 500mm in length with an external bearing separation of 400mm. This provides an adequate counter-leverage factor to ensure that the headstock casting is relatively unstressed by the huge dynamic forces that can be placed on it.
    To better visualise this, imagine that the rear bearing of the shaft is replaced by your

hand. The force you would feel from a static load on the spindle nose would be pushing your hand up and you would exert proportionate downwards pressure to counteract it. The front bearing would be the fulcrum point of the system. A short shaft would severely limit the possible weight of the overhanging load. Conversely, it is easy to see that if the length of the shaft is increased, the forces being focused through the casting where it supports the front bearing are increasingly being directed in the plane of its maximum strength and greater loads can be carried.
    In this picture the mainshaft is acting as a beam and its strength must be calculated to span the gap between the bearings without flexing under any load envisaged. Another fact that now becomes obvious is that a lathe's real performance potential cannot be judged simply by turning a heavy disc — impressive though that may appear. Overhang of the load beyond the front bearing is the factor that will really test the engineering soundness of a lathe's design.
    The VB's shaft is turned from EN8 steel (extremely tough