A continuously-variable ratio transmission system - with electrically-operated expanding and contracting pulleys - provides forward and reverse speeds from 125 to 3000 rpm and incorporates an ultra-reliable, switchable, automatic, solenoid-operated brake. The master electrical controls are mounted on the cabinet stand and consist of a push button starter, forward and reverse switch and a "power on" indicator light. The speed controls, set in a conveniently positioned binnacle atop the headstock, comprise one push-button for "faster", one for "slower", a brake on/off switch and the coolant controls. A vertical window provides an indication of the spindle speed. The lathe is normally supplied ready to accept 5C collets, with a maximum capacity of 1.0625", operated by a quick-action collet closer mounted at the left hand end of the spindle. It is important to know that the this unit (which should be removed weekly for cleaning and lubrication) can be damaged if allowed to run without a collet in place.
Although the early UK-made version of the lathe had an ordinary threaded nose, that from the USA had one with a 4° taper - with types both properly hardened and ground. While the taper type allows the rapid mounting and dismounting of spindle tooling, care must be taken to use it correctly: a fine line engraved on the vertical surface of the spindle nose indicates the location of a T-shaped shallow keyway that must register correctly with the chuck or backplate being fitted; original spindle fitments are marked with a line, circle or dimple to assist in this task. The item is then pushed on to the nose and twisted either left or right to lock it. An ordinary pin type spanner can be used to make the final tightening - do not use a punch and hammer but seek out the correct Williams or Armstrong spanner No. 460 (or a similar quality item). Chucks supplied by Hardinge have an integral fitting to match the spindle nose, so reducing overhang and making the most of the machine's between-centres' capacity. Over the years a number of different makes of chuck were supplied - Hardinge never made their own - including, on early models ones by Skinner and Union and later by Burnerd in England (these are stamped accordingly) and other with a badge proclaiming "Made in USA HARDINGE Mfg by Buck Chuck". It appears that chucks with a built-in Hardinge taper are no longer available and so have to be mounted on a separate backplate; these backplates can be either difficult to find or impossibly expensive, or both, but lathes.co.uk may be able to help.
Fitted with easily-read black and white feed dials both top and cross slides move with a silky smoothness whilst the power sliding and surfacing feeds are both fitted with finger-tip operated, flick-up engagement clutches - of a design identical to that found on the top-class English CVA and American Monarch toolroom lathes. The clutches are a friction type and spring loaded; they are not adjustable and any sign of slippage is an indication that the cutting tool is blunt - or the machine being overworked. For normal, non-screwcutting turning, the saddle is advanced by a variable-speed electric motor built into the apron and controlled by switchgear mounted at the tailstock end of the bed. The fact that the headstock spindle speed and tool-advance rate can be individually controlled means that, whilst the initial setting can be at the text-book approved level, it can (if necessary) be changed by experimentation until the perfect setting is arrived at for the job in hand. Another important advantage of the drive is that it reduces the number of gears involved in the transmission of power - gear drives are bad news for surface finish, they induce vibrations that, whilst usually hidden in the "roughness" of ordinary turning, become much more evident in the finer finishes that high-quality lathes are able to produce.
Screwcutting on the HLV-H is by one of three types of gearbox: English, metric or, more rarely, a dual English-metric unit (when the lathe was known as the HLV-EM). It is possible, as with most lathes, to convert the English and metric boxes to cut the "other" threads as well; however, in the case of the Hardinge, this means the purchase not only of the necessary changewheels but another banjo as well, special ones being manufactured for each of the two conversions. To turners used to the difficulties of screwcutting on conventional lathes - for example, cutting to within a few thou of a shoulder or into a deep recess - the arrangements on the HLV appear as nothing short of magic. The machine can be set to automatically disengage the screwcutting at any pre-determined point - and the drive will drop out flawlessly and accurately every time. Whilst this is happening the leadscrew and clasp nut stay engaged (so there is no need to use a thread-dial Indicator) and all the operator has to do is to return the tool to its start point, apply more cut, and re-engage the drive. Not only does this does work with all pitches of thread and at modest speeds, but also at high r.p.m. - and returning to an "ordinary" lathe after experiencing secure, 500 r.p.m. screwcutting on an HLV is always going to be a disappointment. Another interesting feature of the HLV design is that both cross and longitudinal feeds can be operated simultaneously--which action generates a perfect 60-degree cone. The standard toolpost incorporates a screw-operated wedging arrangement designed to facilitate quick setting of the cutting-tool height--whilst maintaining that all-important ingredient of successful turning, tool rigidity. Also available, in addition to the standard single-tool holder, are various types of special toolpost and individual toolholders.
A positive lubrication system is fitted to the carriage operated by a plunger fitted to the top rear of the saddle and to the right of the cross slide. Lifting and releasing the plunger several times during the working day should be sufficient to keep the cross-slide and bed ways wet with oil. The apron and clutches have a separate oil supply the level of which should be maintained at the half-way line on the sight-glass window fitted in the vertical surface of the saddle at the end nearer to the headstock.
Even the tailstock on the HLV is carefully though out and, with the barrel extended 6 inches, a further 6 inches are retained within the casting. Not all HLV-H lathes were created equal and some - due to the unavoidable vagaries of the manufacturing process - were found to be even more accurate than standard. In the past these special lathes were marketed by the factory as "Super Accurate" and offered at a premium of several thousand dollars above the regular price.
Whilst general maintenance on HLV-H lathes is straightforward (and the various handbooks very helpful) when it comes to any problem with the headstock spindle bearings (see above) these are best left to either the factory or expert re-builders. Obtaining the genuine bearings and fitting them correctly (mishandling will ruin them) is money well spent.
The HLV-H has been copied by several Taiwan firms including Feeler, Sharp, ProMach, Barer (model CTL-618EVS and others) and Cyclematic. In addition some of these makers have supplied machines with "alternate" branding for distribution by dealers world-wide. Feeler was the brand name used by the "Fair Friend Company Limited", originally of 11/F No. 665, Tun-Hwa South Road, Taipei, Taiwan with a factory at No. 805, Chung-Shan Road, Shen-Kang Shiang, Taichung-Hsien, Taiwan. Sharp's copy was beautifully-made and sold as standard with a hardened bed and a 5 h.p. Japanese Yaskawa drive; however, they also offered the "Acra", a less well finished model with a soft bed and minor changes to cut production costs. ProMach, of whom few details are known, referred to their version as the "ProLathe" and sold it until at least the mid 1990s, and possible later. The "Victor", made as the standard CTL-618, the Cyclematic CTL-618EM and CTL-618EVS with electronic variable-speed drive, was by an unknown manufacturer but distributed through the Taiwan Machinery Trade Centre in California. If any reader has further details of these, or other clones, the writer would be pleased to hear from them.
Hardinge also made other machines of interest to the model and experimental engineer: the "Five-Nine Super-Precision Model Shop Lathe" (DV59) and a range of very high quality vertical and horizontal milling machines - some of which were badged, during the 1930s, using the Cataract name.
Surviving Serial Number records
HLV-H (US production):
1960…..0100 1961…..0210 1962…..0554 1963…..1042 1964…..1540 1965…..1905
1966…..2345 1967…..2864 1968…..3327 1969 to 1971 ……? 1972…..5014-K
HLV (UK production - the only data ever discovered)