Mr. Horace Denford
4.5-inch and 5-inch centre height lathes - an overview:
With serial numbers starting at 1001 the first batch of "9-inch" lathes left the company's Box-Trees factory during April, 1948. These first machines (stamped with a DEH prefix to their serial numbers standing for, presumably Denford Engineering Halifax) were basic machines with screwcutting by changewheels and hand cross feed; they were fitted with a 3-step flat-belt drive to the headstock, no countershaft or headstock belt guards and with the motor on/off switch built into the front face of the headstock-end bed foot. The countershaft assembly was built as part of the lathe, making it a self-contained unit, ready to run. It was carried neatly on two bars passing through bosses cast into the back of the headstock-end foot and controlled by a lever protruding through the foot's front face, a "quick-thread" mechanism being provided to slacken and tighten the belt. Bored through 0.75" (on all models save for the later VSL with its L00 nose) the spindle ran in expensive "precision" Timken taper roller bearings (though cheaper but just as effective standard ones were to be used in later years). Collets, sized at C3, were carried in a hardened nose insert and retained by a the usual sort of threaded draw-tube.
Exactly when the gearbox and power cross-feed models were first made is uncertain, but they must have followed within a few months for South Bend had been offering these versions since 1939 and the first known properly printed and illustrated advertising literature does show all three types.
On the very first examples the lathe was clamped to the stand or bench by two in-line bolts that passed upwards into each aluminium bed feet. The next version used three bolts, two being set across the bed and passing through a flange on the inner face of the foot and with the other on the foot's centre line passing through an inwards-facing boss. The final type, and found on most machines, was a simpler arrangement of two bolts - one at the front and the other at the back of each foot. When fitted with optional 2-step pulleys on motor and countershaft, and combined with the 3-step cone (flat-belt) headstock pulley, these early versions had a usefully wide spread of spindle speeds (though bottom speed was too high) of approximately: 76, 140, 250, 390, 710 and 1300 in open belt drive and 40, 67, 120, 190, 350, 640 in backgear. The backgears, though often found damaged on used machines by mishandling, were robust enough to allow the lathe to be easily capable of turning the largest faceplate-mounted job. Both slides of the compound rest were driven by 10 t.p.i Acme-form (or 2.5-mm pitch) screws fitted with 1.6-inch diameter, satin-chrome zeroing micrometer dials - the friction setting of which could be adjusted (or locked) by a pair of spring-loaded ball bearings.
In January 1950 the flat-belt drive was abandoned, with lathe No. 1791 to become the first fitted with 4-step V-belt drive - a much-improved arrangement that gave a more useful bottom speed (ideal for screwcutting by beginners) and a total of 16 rather than 12 speeds. To convert a flat-belt machine to V-belt specification is simple for the pulleys interchange without any modifications being required. The standard V-belt speed range consisted of: 38, 55, 87, 125, 75, 110, 175 and 250 r.p.m. in backgear and 200, 285, 450, 650, 400, 570, 900 and 1300 r.p.m. in direct (belt) drive. At the same time the tumble-reverse mechanism was altered with the inconvenient and slow-to-change bolted-up arrangement being replaced by a simple, quick-action, spring-loaded plunger design.
One unusual, possibly unique model, probably constructed during 1949/50, was a gap-bed model of which only one example is known and currently in South Africa. Using otherwise standard parts - headstock, carriage assembly and tailstock, it was built as a Model A and might have been inspired by South Bend's almost simultaneous introduction of a similar type (the Boxford being based, of course, on the South Bend "9-inch") or possibly a prototype machine taken to South Africa by an ex-employee. It might even have been one of a batch built to a specification required by an importer or Government agency; however, it's almost certain that it's origins will remain forever a mystery.
In 1951 a very slightly cheaper version of the ordinary Boxford was introduced, the 4.5" x 16" Model CSB. Unlike the £112 Model C, which lacked a motor in the basic price, the CSB was delivered complete and ready-to-run with a 1/3 h.p. motor for £105 - a total saving of some £16 : 5s : 0d. Other prices in 1951 were: Model A £170 (22" centres) and Model B £142 (22" centres) with an extra £8 and £9 respectively charged for the long-bed with 28" between centres (by 1955 prices had risen to £185, £155 and £125 for the A, B and C respectively). The rear-drive lathes remained in this new V-belt drive form until 1959 and the introduction, from approximately Machine No. 8755, of the "Underdrive" Type, a range of 10-speed lathes with the motor inside the cabinet stand and eventually to be built as the TUD, CUD, BUD , AUD & VSL). Made from welded steel plate, the new stand held the countershaft and motor assembly, the optional coolant tank and motor and provided, in its right-hand compartment, storage shelves with a collet tray fastened to the inside of the (locking) door. Belt tension was released by an external handle that protruded through the stand's left-hand face, a fitting that provided a strong temptation to use it as a clutch - a potentially dangerous undertaking. This weakness (from a safety point of view) was removed when the mechanism was redesigned and made accessible only by opening the door. The new lathes were sold as "AUD", "BUD", "CUD" and "TUD" models (with the "UD" suffix standing for "under-drive", of course) and "A", "B" and "C" reflecting, as before, the specification. However, the new models did not replace the old, but complimented them, the original rear-drive types remaining in the Boxford catalogue (optimistically, one would have imagined) until at least 1977. With the introduction of the Under-drive models came a superior cosmetic finish with the castings carefully fettled, filled with cellulose knifing putty, rubbed down and spray painted. While not to the standard of the Raglan lathe, with its use of special Trimite paints, this new finish (generally in a grey cellulose to BS692 sprayed over a filler) was a considerable improvement over the earlier lathes, the first of which had, to be blunt, a decidedly utilitarian appearance.
Although the rear-drive models suffered from a very deep countershaft, and consequently took up a good deal of room, the under-drive versions were very compact - with a bare stand only 17 inches front to back - and today are consequently by far the more popular buy second-hand.
From December 1973 - approximately Serial No. 33000 - the swing was increased to 10 inches, but with the rear-drive lathes remaining at 9 inches. The distance between centres offered varied over the years: at first all types were offered with 16", 22" or 28" - the latter being very rare. Later, only the two longer beds were offered, the 16" option being consigned to the cheaper CSB model. All Boxfords were "straight bed", that is, none of them, unlike some models of the South Bend 9-inch of the early 1950s, had a gap. Besides the conventional V-belt drive already described, the lathe was also marketed as the comparatively rare VSL with expanding and contracting pulleys giving a useful mechanically-operated variable-speed drive system.
Later Under-drive lathes of all versions enjoyed a number of refinements and are known as the "Mk 2 Under-drive". They were built with a 4.5-inch centre height from the 1st of December 1963 (probably serial number 11-13513) and from December 1973 (around Serial No. 11-33000) as a 5-inch model (the "11" prefix indicated the Mk. 2, earlier models generally had no such stamping though the prexfix "10" has been seen on some examples). The main improvements centred on increasing operator safety and ease of use: backgear no longer need two levers to be engaged, instead the initial movement of a single, electrically-interlocked lever on top of the headstock released the bull-wheel from the spindle pulley and the final push sliding the gears into engagement. On early versions the large headstock gear was left "as cut" but later models (from an unknown date) had the leading edge of the teeth rounded to ease engagement. A useful addition was a spindle lock, operated by a dished chrome-plated button on the face of the headstock; this greatly eased the removal and fitting of chucks and faceplates and obviated the need to use, and possibly damage, the backgears. At the same time the opportunity was taken to reposition the various headstock oil nipples so they could be reached without having to open or remove any covers. To give a stronger assembly and quieter running the pressure angle of the backgears, the tumble-reverse gears and the drive gear on the end of the headstock spindle, was changed from 14.5° to 20° - although the changewheels themselves remained unaltered. The top slide was provided with an extra 3/8" of movement (that usefully increased it to the same length as a No. 2 Morse taper) and both top and cross-slide feed-screws (actually from Machine No. 12419 in January, 1963) fitted with ball-bearing thrust assemblies, the inner and outer hardened plates of which, over time, can become indented and give the action a "gritty" feel.. The micrometer dials were satin-chrome plated and fitted with an improved friction "clutch" that did away with the need to lock the setting with an Allen key, while the degree-indexing marks (to indicate top-slide swivel) were moved to an angled surface in an effort to make them easier to read. Unfortunately, the rather awkward (not to say crude) method of adjusting the position of the micrometer dial on the cross-slide screw, involving a grub screw through the handle into a dimple on the shaft, was not changed. Captive nuts were fitted to the underside of the motor-mounting plate so that adjusting the belt tension on the primary-drive involved no more than slackening the clamping bolts and sliding the motor into the correct position; the countershaft spindle was increased in diameter, fitted with sealed-for-life deep-groove ball races and the motor-end cabinet door louvered to improve cooling. To improve lubrication of the countershaft bearings - and avoid having to open the door to do this - the end of the countershaft was arranged to protrude through the left-hand face of the stand so that oil could be injected by the direct application of a pressure gun. Electrical interlocks, by micro-switch, were fitted as standard to the backgear lever, changewheel guard and motor-cabinet door - but these could, if not required, be eliminated from the specification of a new machine and the price reduced by £1 : 10s : 0d (£1.50) for each unit left off (to disable the electrical locks on your own Boxford it's possible to bridge their contacts on the terminal block fitted at the rear of the headstock-end bed foot). To improve the appearance of the lathe some small but significant improvements were made to the fit and finish of various components including more precise mating of the headstock-to-changewheel guard and bed-to-screwcutting gearbox faces. The appearance of the tailstock was also cleaned up and, as a final touch, a modified catch - though still largely useless and easily-opened - was fitted to the changewheel guard.
Some confusion surrounds exactly when the final version of the Underdrive, the Mk. 3, was put on the market. The official release date was May 1976, but machines have been found that pre-date this, for example: AUD III-33777 with a bed casting dated 1974 and with year also correctly corresponding to the Serial Number list. These lathes were distinguished by a more modern-looking stand complete with a neat splash-back, standard-fit low-voltage halogen light unit and a rather elegant grey and brown finish. However, the designation Mk. 3 was never acknowledged in the advertising literature, though it was used in the spares department to identify the particular models. During October and November 1981 the colour scheme was changed, temporarily, to green - a shade that can be replicated by ordering "Reseda Green B.S. Standard RAL6011".
After a production run of 40 years the last of the "traditional" style Boxford lathes left the factory during January 1988 with Serial Numbers finishing at around 43261. However, if you count manufacture of the type as beginning with the very first 9-inch South Bend, the Model 405, of late 1933, that would give a production span for the type of 55 years.
The various models - specification details:
Model VSL (4.5-inch centre height) & Model 500 VSL (5-inch centre height)
The VSL was built with both 4.5 and 5-inch centre heights with the latter version being listed as the Model 500 VSL. Introduced as a 4.5-inch centre height machine in January 1966 (from Serial No. 18970) both are very desirable machines - but, unfortunately (especially the 500) difficult to find. Apart from a very rare, non-screwcutting, capstan-equipped export version with a "Harrison" label, the VSL was made only in Model AUD form with an under-drive stand, screwcutting gearbox and power cross feed. On early versions only the drive system was altered, to a mechanical variable-speed type, with the rest of the lathe having the same specification as the AUD and appearing, mechanically, to be almost identical to it. However, some effort had been made to upgrade the machine and, instead of cast-iron (used on all lesser models) the VSL, from first to last, appears to have had backgears in induction-hardened steel together with larger locating holes in the front face of the spindle bull wheel. To improve the reliability of the tumble-reverse gears they were equipped with needle roller bearings. Later models were much improved by the fitting of a larger 1.375" bore spindle with a hardened and ground American Standard L00 taper nose and a 5-Morse taper socket - together with a short, hardened reduction sleeve (to take it down to 2-Morse) and an adaptor to accept direct-fitting C5 draw-bar operated collets (other Boxford models took a C3 collet in the same type of insert nose fitting).
Fitted with a wide "expanding-and-contracting" V-pulley mounted directly on its shaft the electric motor was mounted inside the left-hand side of the cabinet stand. Pulley movement was controlled by a cable and rod system driven from a handwheel on the front of the stand. The upper drive pulley, which reacted to the movement of the motor pulley by opening and closing automatically, was carried in bearing hangers from which a second (conventional) link-type V-belt took the drive up to the headstock spindle. The speed range was typically 50 to 2000 rpm and, because the drive was infinitely variable an electronic rev. counter (later a mechanical one) was fitted to show the operator what was going on (later versions were wired direct through the Forward/reverse switch, earlier types through a contactor, then through the forward/reverse switch). If the tachometer is broken or missing, businesses specialising in vintage car and motorcycle restoration can often help with replacement or repair. Some early 4.5" centre-height VSL lathes were fitted with a motor having an extended left-hand shaft that carried a very expensive electro-mechanical disc brake, controlled by a switch fitted to the left-hand face of the motor-control panel. Nearly all VSL lathes were supplied, when new, with 3-phase motors - 930 r.p.m./1-h.p. on the screwed-spindle nose models and 930 rpm/1.5-h.p. for the L00 version. Unfortunately, because the drive mechanism fitted to them has to be accurately aligned to work properly, the VSL is difficult to change to single-phase operation. In addition, because the coolant pump, light unit and safety-interlock transformers are also 440 volt 3-phase (though some may be on step-down transformers to run at 110V), rather than attempt to completely re-engineer the peripheral controls, it is much easier to leave everything in place and run the lathe from a phase converter or inverter. If this is done it is worth bearing in mind that, while the main motor can be easily altered from "Star" 440 volt to "Delta" 240 volt working, many of these machines were fitted with both a push-button safety starter of the front panel and another "automatic" contactor unit at the rear. Because the coils in the contactors are 440 volt they usually refuse to work when supplied with the 220/240 volts put out by the inverter. Coupling the inverter (as is usually recommended by their makers) directly to the motor and bypassing the built-in controls has been known to produce a far more effective conversion. Of course, doing this means that the safety-interlocks on doors and backgear are lost and other arrangements have to be made to power the coolant pump and light unit*.
Fitted to a distinctly different stand, and with a 5-inch centre height, the final version of the VSL was known as the Model "500 VSL". Unlike most Boxford lathes the VSL500 was clearly identified by a large badge on the headstock. An interesting point concerns VSL models fitted with the LOO spindle: on these lathes a screwcutting gearbox was standard, but with changed internal ratios and the availability of "compact" English/metric and metric/English conversions gears i.e. instead of the older "full-size" 127/110t (inch to metric) and 135/127t (metric to inch) gears the LOO versions were, respectively: 64/54t and 76/65t.
From November 1976 Boxford began to market 5" x 22" Model ME10, a less expensive lathe - though constructed from components identical to machines higher up in the range. Early ME10s had a normal, full-length countershaft and were little different to the run-of-the-mill rear-drive models - the aim, presumably, being to use up supplies of no-longer-needed parts as the successful under-drive models took centre stage. Also available mounted on a special stand, the lathe was intended to run alongside the under-drive and rear-drive models and could be had in any of the three usual A (gearbox and power feeds), B (changewheels with power feeds) and C (changewheels and hand-cross feed) specifications. The main difference between the later ME10 and the ordinary rear-drive models was the significantly reduced amount of room required to install it - a much more compact countershaft arrangement being used that made it far more suitable for the home workshop--the market segment that Boxford must have been targeting. In order to shorten the belt run two brackets were bolted to the back of the headstock with each carrying an inwards facing stud from which hung a casting that formed, at its rear, two bearing housing. Supported in the bearings was a shaft that held, on one end, the large pulley driven from the motor and, between the bearings, the 4-step pulley used to drive the headstock spindle. Most models of the ME10 are found with the latter drive system, this allowing covers to be used that, unlike earlier designs, required no extra room to be swung fully open. As a consequence, fitted to its own cabinet, the ME10 took up only a little more depth than the under-drive versions. One difference noticed on these lathes, though it's not certain that all were so equipped, is the use of quieter-running, Oilite-bushed, tumble-reverse gears in fibre. The fibre gears can be fitted to all other models and have definite advantages if the lathe is to be used where noise might be a problem though of course, being weaker, reliability is not so certain. One (expensive) option offered on the ME10 was an effective spindle clutch - a fitting that, sadly, was never made available for other versions and remained exclusive to the model..
Another slightly cheaper model was the 'CSB' - possibly for "Model C School Boxford". This was first offered in 1951 and was, in essence, just a short bed (16" centres) Model C but with a simplified 8-speed drive with the motor bolted direct to the countershaft upright instead of on a separate, adjustable horizontal motor platform. With a single-pulley drive on motor and countershaft, and using backgear, the eight spindle speeds were: 38, 55, 87, 125, 200, 285, 450 and 650 r.p.m. By paying £3 : 10s : 0d extra the motor and countershaft could be fitted with 2-step pulleys when the speeds became: 38, 55, 75, 87, 110, 125, 175, 200, 250, 285, 400, 450, 570, 650, 900 and 1300 r.p.m. Unfortunately the makers neglected to mention the fact that in order to run on top speed a more powerful and expensive motor was required. To adjust the motor-to-countershaft belt tension meant repositioning the motor itself - however, once this had been done it was not normally necessary to make any further changes until the belt began to wear. Early examples of the CSB were different, and fitted with the novel, quick-action belt-tensioning device used on the lathes of the late 1940s - probably another case of using up no-longer-needed spares. Other evidence of clearing storeroom shelves was the use, throughout the life of the model, of an early-pattern South Bend type saddle with its simple screw-in, rather than bolt-on, cross-feed screw support bracket. Ambitious advertising in the model-engineering press of the day attempted to position the CSB as an alternative to the Myford ML7; unfortunately the Boxford cost nearly twice as much and, while it did offer a range of advantages, there can have been few takers. A "Training" version of the lathe, the CSBP, was also offered: shorn of screwcutting equipment and usually, but not always, backgear, this model was aimed at the school and college market and had little appeal for the model or experimental engineer..
Models T and TUD Training Lathes
Both the T and TUD plain-turning training lathes were dimensionally identical to the more highly-specified models and used the same basic castings; however, they lacked any form of screwcutting, power feed and, more often than not, backgear. The rear-drive system usually gave 4 speeds from around 200 to 1200 r.p.m. - although the writer has seen examples with 2-step pulleys on motor and countershaft to give 8. The under-drive models had 5 direct-drive speeds of 210, 340, 540, 850 and 1400 r.p.m. or, with backgear fitted, an additional 5 slower speeds. The development of the training lathes mirrored that of the more highly specified versions changing from rear to under-drive and then incorporating the other small improvements already described. The last versions were of 5-inch centre height and mounted on a version of the more modern-looking stand - and even complete with the splash back, chuck guard and halogen light unit. Although an attractive proposition, because of their low price, the plain-turning versions are of limited use other than in a training role, for the very simplest of work - or as a back-up lathe for roughing out. Can they be converted to full-specification machines? I do known one person who managed it, but he enjoyed the unfair advantage of working night shifts at the Rolls-Royce aero-engine factory in Derby and had access to, shall we say, a rather comprehensive range of workshop facilities. In other words, the conversion is possible, but not even worth considering - unless you can find all the missing bits and enjoy the skills necessary to make the most of comprehensive turning, milling, grinding, boring and fitting facilities.
Drive Systems, Countershafts and Belts:
Because the 9-inch lathes had been flat-belt driven the maker, following usual practice to optimise grip, had set the pulleys as far apart as reasonably possible. However, even after a change to V-belts (and through two changes of countershaft) Boxford made no effort to take advantage of the shorter centres on which these can run to make the machines more compact. Early lathes, until machine No. 4600 in 1954, used an "integral" countershaft unit of unusual and ingenious design where the pulley system and motor were both mounted on a platform that could be adjusted forwards and backwards on two bars fastened to the back of headstock-end bed foot. The movement was activated a quick-action, two-start thread controlled by a handle on the end of a shaft that protruded through the front face of the bed foot immediately below the headstock. When moving these lathes, take care to support the rear of the countershaft otherwise the bars on which it sits may be bent. On later rear-drive models a very heavily built, separate 16-speed countershaft of different design was fitted with the motor mounted on a rather over-engineered (even unnecessary) horizontal platform. This allowed a separate adjustment to be easily made to the motor-countershaft belt tension. At some point the new countershaft was modified and its right-hand bearing made detachable to ease belt replacement - though it was still necessary to completely dismantle the headstock if a standard V-belt was to be used.
One problem sometimes encountered with both underdrive and rear-drive versions is vibration at high speeds and/or a knocking at lower; this can nearly always be traced to either the large countershaft pulley being out of balance or either (or both) the drive belts being unevenly worn. Well-used belts (or belts with stiff sections, caused by being left under tension for some considerable time) fall into and then ride up the pulleys, effectively varying the drive ratio, causing the speed to rise and fall rapidly and so induce vibration. Should you suffer this problem it's worth replacing both belts (the "T-link" belt on the headstock drive saves dismantling and can also, with advantage, replace the standard V-belts on the other parts of the drive). New, high-quality machine-tool specification belts (which we can supply, just email for details) can make a significant improvement to the smooth running of any machine tool. and then, if that does not affect a cure, removing the countershaft pulleys and shaft and statically balancing them between a pair of lathe centres.
A serious problem with the rear-drive machines when used in educational establishments was the difficulty of securing the belt guards against curious fingers. Most schools had to resort to bolt-on straps and similar Heath-Robinson approaches and, as a consequence, in 1959, Boxford introduced the "Under-drive" models, a design very similar to the competing Viceroy and as already offered for many years by South Bend, Clausing, Sheldon and other American manufacturers. With the drive now held securely in the stand behind an electrically interlocked door another advantage emerged: the depth of the machine was reduced to as little as 17-inches (400 mm).
Early under-drive lathes had their countershaft-spindle bushes pressed directly into the material of the motor platform itself, with the belt-tensioning handle mounted externally on the left-hand side of the cabinet. With the handle so temptingly placed many owners were inclined to use it as an unofficial (and dangerous) substitute for a clutch. In 1960 the countershaft was modified: the shaft diameter was increased to 0.75" and, in 1966, further improved when the shaft was increased to 1-inch diameter, the bearings fitted to removable brackets, the belt-tensioning lever repositioned within the cabinet base and the access door (like the educational versions) provided with a micro-switch that stopped the motor should it be opened by even a fraction of an inch.
While rear-drive lathes had 6, 8 or 16 spindle speeds all the under-drive machines, with the exception of the variable-speed VSL, were limited to 10. With some variations, because of special orders or educational and training use, the usual range on the back-drive type was 30 to 1250 rpm while the Mk. 1 and Mk. 2 Underdrive types of all models (CUD, BUD and AUD) generally ran at 40, 66, 105, 165 and 270 r.p.m. in backgear and 210, 340, 540, 850 and 1400 r.p.m in open belt drive. However, on the latter machines (at extra cost) the factory could provide a more powerful motor and a "high-speed" pulley set that increased the maximum to just over 2000 r.p.m. - but at the sacrifice of increasing the bottom speed to such an extent that it was difficult for beginners to cut threads.
It's well known that a lathe fitted with a spindle clutch is a good deal easier to handle than one without - and it remains a mystery why the only Boxford ever so fitted (as an option) was the ME10. Its design was similar to that used on the Myford ML7 with a brake-drum housing formed inside the countershaft drive pulley and an operating lever working through a push rod and toggle-arm that opened and closed a pair of brake shoes. Owners of clutch-equipped lathes report that the unit is not only reliable, but has a pleasingly light yet positive action.
Metric & English Screwcutting
All models of Boxford - from first to last - had 18DP changewheels, 0.375" wide. with a 14.5° pressure angle and a keyway. Because the company had strong connections with the educational and training world, many lathes sold during the 1950s were specified as "all-metric" machines. Interestingly, although large numbers were sold set up in this way, some were fitted (but probably unknown to their first owners) with an imperial leadscrew driven by a metric-conversion changewheel set. The factory were obviously keen to use up stocks of leadscrews that would otherwise have languished unused in their stores - and must have guessed that the likelihood of schoolchildren ever being allowed to use a lathe to cut threads was little better than zero. This, needless to say, resulted in a great deal of confusion when the machines eventually passed into private hands. Boxford's careful control of production costs has, however, done every subsequent owner a considerable favour for, providing that the lathe has its original set of changewheels the addition of a few more produces, at little cost, a dual metric/English screwcutting machine. Later metric machines, and all the metric-gearbox equipped variants no matter what their year of manufacture, were fitted with a proper metric-specification 3 mm-pitch lead screw.
Identical to that used on the original 9-inch South Bend, the screwcutting and feeds' gearbox contained components that were neither hardened or ground and lacked oil-bath lubrication. Instead, a lever-action oil can had to be used on a series of ball-oilers to lubricate the spindle bearings with the gears attended to by squirting inside on a hit-and-miss basis. Even so, the box is remarkably reliable and, if oiled generously, will not give trouble.
English and metric screwcutting versions are different, but can be easily distinguished one from the other: the English box has the diagonal line of indent holes on the right-hand half of the box's front face while for the metric version they are on the left.
Changewheels and English/metric and metric/English conversions
"English" threading Lathes with an 8 t.p.i. leadscrew and changewheels for screwcutting (i.e. without a screwcutting Gearbox) were supplied with the following changewheels when they left the factory: *16, 24, 36, 40, 44, 46, 48, 52, 54, 56, 60, *80, *72/18 compound, *80 idler (with boss). (* gears on machine as dispatched from factory for standard feeds)
To convert a non-gearbox English-specification lathe to cut metric threads the following gears are needed: 20, 100, 127/100 combination
In addition, to cut the following five pitches extra gears are required as follows: 0.45 mm = 18t gear, 0.55 mm = 22 t gear, 0.65 mm = 26 t gear, 0.7 mm and 3.5 mm = 28t gear
Metric Threading Lathes with a 3 mm pitch leadscrew and changewheels for screwcutting (i.e. without a screwcutting gearbox): were supplied with the following gears as standard. *16, 24, 28, 30, 36, 40, 44, 48, 52, 56, 60, *80, *72/18 compound, *54/18 compound, *80 idler (with boss)
(* gears on machine as dispatched from factory for standard feeds)
To convert a non-gearbox Metric-leadscrew lathe to cut English threads the following gears are needed: 18, 22, 26, 38, 54, 64, 88, 135/127 compound, 48/24 compound.
"English" threading Lathes with a screwcutting gearbox had a standard ex-factory drive train consisting of: 20t, 40t, 56t and an 80t idler. To convert this gearbox to cut Metric threads the following gears are needed: 24, 26, 28, 32, 36, 44, 48, 127/100 compound
Metric threading lathe with a screwcutting gearbox had a standard ex-factory drive train consisting of: 20t, 45t, 50t and an 80t idler. To convert this gearbox to cut English threads the following gears are needed: 38, 40, 44, 52, 56 and a 135/127 compound.
An interesting point concerns VSL models fitted with the L00 headstock spindle: on these lathes a screwcutting gearbox was standard - but with changed internal ratios and the English/metric and metric/English conversions gears arranged to be more compact with (instead of the older "full-size" 127/110t (inch to metric) and 135/127t (metric to inch) gears) pairs of 64/54t and 76/65t respectively.
If you buy a gearbox-equipped lathe that appears not to generate the pitches shown on the screwcutting plate check this page--it shows the ex-factory arrangement of the changewheels.
All the gears necessary to generate metric and other pitches are now available at a good saving on the factory price
Early headstocks, certainly those up to the introduction of the Under-drive models, were fitted with bearings having 14 rollers and marked "Precision 5" (with inner and outer races coded 2720 and 2788 respectively). Today, when available, these "selectively-assembled" units are very expensive - several hundred pounds each - but, as Boxford fitted later machines with cheaper standard-specification bearings (17 rollers and a shallower cone angle) there seems to be no good reason why a substantial saving cannot be made by using these bearings in all versions of the lathe. From December 1975, around Serial No. 35000, the headstock bearings were listed as being "greased for life"; however, these were not sealed bearings, but just packed with what the makers hoped would be sufficient lubricant to last for many gears. If a lathe without grease caps has been standing unused for several years, it might be a wide precaution to strip the headstock and check to see if the lubricant has solidified.
If the lathe is run very hard and at high speed and taking deep cuts, it is not unknown for the spindle bearings to overheat; while a modest ruse in temperature is quite normal if the headstock casting temperature exceeds around 40°C it's best tom stop and let it cool down. One solution, seen by the writer on an Underdrive model, was the fitting of a computer case fan in the sheet-metal belt cover on the back of the headstock. This was controlled by a temperature probe, switching on at 40°C and off at 45° and the lathe was able to run all day on its highest speed taking deep cuts on resilient materials.
Aprons and Power Feeds
It is sometimes not appreciated that lathes with power cross-feed (models A and B) benefited from a range of slower longitudinal feeds than the Model C - the reduction through the apron's worm-and-wheel gearings meaning that the feed rate was reduced by a factor of 0.3. In addition, because the power-feed drive was taken from a key running in the slotted leadscrew, the thread in the latter was needed only for screwcutting, so preserving its accuracy and saving wear on the expensive clasp nuts. The power-feed apron was identical to that used on the South Bend with the drive taken through what was, in effect a cone clutch wound into engagement by a star-shaped knob on apron's front face. If this clutch is allowed to slip (by regularly running the carriage up against a bed stop for example) the mating surfaces of the cone will eventually become polished and, no matter how tightly the knob is screwed in, will slip badly. The solution is to strip the clutch and roughen all the friction surfaces - the spilt cones and their seating - with fine emery cloth; once done this will allow the drive to deep cuts with only the lightest of pressure on the control wheel. A useful thing to know when dismantling the apron is that the screw in the centre of the clutch wheel has a left-hand thread. On late machines, for both safety and ease of use, the clutch wheel was prevented from rotating by the use of needle-roller thrust bearings fitted to both front and back of the engagement shaft with a peg added to its end that located into a hole in the cover plate. These late-model aprons can be instantly recognised by their black plastic clutch-control wheel. Unfortunately the clasp nuts, through of a straightforward design, do tend to fill up with swarf and dirt and so, to protect the leadscrew, it's worth removing the apron from time to time and cleaning them carefully. In the case of the Model C, where the clasp nuts are in constant use (taking the place of the power-feed mechanism) it may be necessary to pick embedded material from the thread roots with a sharp-pointed tool. An adjustable friction device - a spring, ball bearing and socket-headed Allen screw - located underneath the apron towards its tailstock end helped to hold the clasp nuts open or closed. An interesting article on rebuilding a Boxford/South Bend/Hercus power-feed apron can be seen here.
Apart from the method of retaining the barrel-feed screw, and a centre-height change from 4.5 to 5 inches, the design of the tailstock remained unchanged throughout the life of the machine (though there was a cosmetic improvement when the Mk. 2 Under-drive machines were introduced). The 11/16-inch diameter barrel had a travel of 21/8 inches, carried either inch or metric ruler engravings, and occasionally both, with a self-eject mechanism for the No. 2 Morse taper centre. Although the barrel clamp was a proper compression affair the operating lever was too short - and consequently it can be difficult to get enough force to lock things down solidly. The top could be set over on the sole-plate for a maximum distance of 5/16-inch for taper turning and, while the bed clamp was entirely adequate, it did need careful flat-by-flat adjustment of the base nut within its retaining slot if the lever was to lock in the ideal place some 30 degrees forward of vertical.
Virtually every accessory is interchangeable across the model range and, in addition, many of those made for the 9-inch South Bend, and Smart and Brown Sabel (and other clones) also fit. Even the fixed steady from the later 5" lathe is useable on the smaller machine (and visa-versa) if you are prepared to give up a little of its maximum capacity. Unfortunately Boxford accessories do tend to be rare, and hence more expensive second-hand, than their Myford equivalents. Amongst the hardest items to find are the standard and compound milling slides; the former used a very robust main column that fitted into the hole in the cross slide normally occupied by the top slide and was supplied with a T-slotted table and a vice, both able to be used independently on the cross slide. Boxford also produced a beautiful dividing unit based on the same fitting - but this was always an astronomic price - and very few can have been sold. The compound milling slide is, likewise, very hard to find and, being so versatile, greatly sought after.
There is a high degree of parts interchange-ability between the various models - and also between South Bend 9-inch lathes and Boxford; three popular improvements to the latter are: fitting a screwcutting gearbox, a power cross feed apron and a T-slotted cross slide. For the gearbox and power-feed conversion you will need, as a minimum, not only the major parts but also the correct changewheels (20t, 45t, 50t and an 80 idler with a boss) the slotted leadscrew and the correct "Y-shaped" changewheel bracket. The bracket used on the B and C is, incidentally, slightly different, with the bulge round the clamping bolt hole tending to foul the gearbox. On early lathes it will be necessary to drill an extra hole through the bed at the headstock end to take the third gearbox mounting screw. The South Bend has a rack-and-pinion carriage drive of a coarser pitch than the Boxford and it may be necessary on some machines to make an adjustment to the height of the leadscrew by inserting shims between hanger brackets and bed. The leadscrew will also need to be swapped over, or the existing one modified to fit the gearbox, and a slot milled along its length to drive the apron worm wheel. When everything is in place check (by hand and with the changewheel bracket removed) that the assembly rotates easily. If it doesn't, slacken the screws holding both the gearbox and the leadscrew hanger bracket and re-tighten them a little at a time, rotating the leadscrew while you do so, in order to locate the fault. Unfortunately there is a caveat to all this for, while the gearbox is a problem-free fit - and nobody has yet found any difficulty with the apron and cross-slide arrangements - if the parts come from a South Bend there may be a problem. Experienced South Bend mechanics report that the company did not hold the tolerances of saddles fitted to the C to the same tightness as those intended for an A. The result is that the gear on the cross-feed screw may not mesh properly with its apron-mounted drive, being either too slack or too tight. Interestingly, the writer knows of one Boxford that was successfully fitted with the (single-tumbler) screwcutting gearbox and gear drive from a South Bend "Heavy 10": the box bolted straight onto the Boxford bed with the only change necessary being to the tumble-reverse gears that needed changing to match that on the end of the spindle.
The T-slotted cross slide is a direct replacement for the standard unit and makes the lathe significantly more versatile - being able to accommodate a rear toolpost and various non-Boxford milling slides. The T-slotted slides are relatively expensive items but excellent new UK-made units are now available from us--email for details.
It is worth noting that, when supplied by the works with a taper-turning attachment, lathes were fitted with a different design of cross-feed nut held on with two screws instead of the usual boss - these too, along with standard nuts, feed screws and micrometer dials, can all be supplied.
Parts and Accessories Availability
lathes.co.uk usually have a supply of high-quality UK-made accessories and spares suitable for Boxford lathes - including new T-slotted cross slides, faceplates, backplates, changewheels, cross feed screws and nuts, micrometer dials, etc. These parts also fit South Bend and many other South Bend "clones". The design of the T-slotted cross slide has recently been revised to improve its versatility and now features a slot across the front - as well as three to the rear - and fully machined sides. These modifications allow the unit to be adapted as a small boring table - and provide flat vertical locations against which jobs can be registered. The later type of "inset" rotational scale for the top slide is also included, so the unit can be used in place of the normal slide for ordinary turning operations.
If your cabinet stand has broken or non-operating handles and locks replacements (Part Nos. 7/09302 and 7/23057) can be obtained from http://www.faparkes.co.uk/
Floor Space and Weights
Under-drive lathes with shorter beds (up to 24" between centres) take up very little room in relation to their capacity; their stands are often only 450 mm (17.5 inches) deep with short-bed lathes of all types (either stand or bench-mounted) being approximately 1200 mm (47 inches) long (not much more than an Myford ML7) while long-bed versions run to about 1350 mm (53 inches).
Weights vary with bed length and specification but the approximate maximum figures likely to be encountered (as longer-bed examples) are:
Model A 172 kg (380 lbs)
Model B 166 kg (355 lbs)
Model C 163 kg (360 lbs)
Model AUD 263 kg (580 lbs) Model Mk. 2 AUD 276 kg (610 lbs)
Model BUD 256 kg (565 lbs) Model Mk. 2 BUD 269 kg (595 lbs)
Model CUD 254 kg (560 lbs) Model Mk. 2 CUD 267 kg (590 lbs)
Model VSL 300 kg (660 lbs)
Model ME10 141 kg (310 lbs)
Because a Boxford can be broken down very quickly into manageable lumps moving one is relatively easy - a standard Underdrive model can be transported in most hatchbacks with the rear seats removed. With the two screws securing the tailstock-end leadscrew hanger bearing removed the entire carriage can be slid off the bed; the changewheel banjo can be slipped off after pulling the leadscrew or gearbox input gear off its shaft (don't loose the key); the headstock is secured by two bolts, the front one of which poses the greater challenge and requires a very short open-ended spanner and some knuckle-scraping work to undue. If the lathe has a gearbox, leave it in place - and try not to remove a lathe from an under-drive stand; a compound was used to stop coolant getting into the wrong places and effectively sticks the lathe down; once broken the hardened sealer has to be chipped off and the joint remade.
Notes on Lathes Fitted with 3-phase Motors
If your Boxford has a 3-phase motor the best conversion is to run it from a variable-speed inverter; these are wired direct to the motor and replace the lathe's conventional electrical controls. For more in inverters see: http://www.lathes.co.uk/page27.html Unfortunately most Boxford lathes were equipped with either a 0.5 or 0.75 h.p. motor and these, if the lathe is to be run to its maximum capacity, are barely adequate. Although more expensive, the writer would recommend replacing the original; 3-phase motor with a more powerful one; in his experience this transforms the lathe, making it so very much more useful and easy to use.
If a conversion to 1-phase electrics is desired, while the rear-drive machines have a reasonable amount of space behind the lathe to fit a replacement motor (although capacitor boxes may have to be relocated) the under-drive lathes are a little tight on room and, although the conversion is perfectly straightforward, there are one or two simple points worth bearing in mind: the original motor, if 3-phase, will almost certainly be 0.5 h.p. if originally supplied to the education and training market, or 0.75 (and occasionally 1 h.p.) from the industrial sector. Replacing it with a modern 0.5 h.p. 1-phase motor will mean, inevitably, that the lathe will no longer be able to start on top speed and, even if it does, will have insufficient power to be useable. The experience of many users suggests that a minimum of 1 h.p. is necessary for a successful installation, while others consider that an even better solution is to use a 1.5 h.p. motor. In the latter case, problems may be encountered getting it into the limited space available, especially if it's a modern type with a large plastic box shielding the capacitor and terminals. First, install the motor as far back on its mounting platform as possible (you will need to drill new holes in the plate) having first checked that there is still enough room for the belt-tensioning rod to function properly. Second, to enable the motor to clear the floor, lift its mounting platform as high as possible on the over-centre adjuster and use a shorter T-link belt for the drive - it might even be necessary to adjust the length of the tensioning rod to accomplish this. Another trick is to remove the plastic box from the motor and remount the capacitor remotely, preferably in a place where replacement is easy when it fails (as it will). Do not forget to engineer a suitably safe cover for the terminals and clip any new wires securely to the stand. As a last resort, because the base of the motor compartment is open, the stand can be mounted on raiser blocks at each corner and the motor allowed to hang down into the space created.
If the original 3-phase wiring and switches are intact leave them all in place and wire the replacement motor to a new switch with fresh cabling - this makes a future re-conversion to 3-phase (or the 3-phase motor run from a variable-speed inverter) an easy matter, and might even enhance the value of the lathe.
Alternatively, and especially if the lathe has coolant and low-volt lighting fitted, consider running it from a 1-phase to 3-phase phase variable-speed "Inverter"; although a little more expensive than a motor change, once you have one of these units it can be used to power other 3-phase machines, all of which are more readily available, and invariable cheaper, than their single-phase equivalents. As the inverter provides a variable-speed output it will, if coupled to more than one motor - the suds pump for example - vary the speed of both. In practice *many people who have combined several motors running from one unit report that it causes no problems. With prices now at an affordable level, the advantages of inverters are becoming more widely appreciated - and a small lathe fitted with one is certainly a much easier, more versatile and safer tool to use.
If you have the slightest doubt about wiring in a new motor, or modifying the electrics on your lathe, pay a suitably qualified electrician to do the job for you - it will be money well spent.