Introduced in the early 1960s, the Martin DLZ502, DLZ602 and DLZ702 were of the usual outstanding Martin quality, heavily constructed with scrupulous attention to detail and the use of fine-quality materials. All three models of identical mechanical design and construction and differed only as to their centre height these being, respectively, 10 inches (250 mm), 12 inches (300 mm) and 13.75 inches (350 mm).
All were built on the same very deep, closely cross-ribbed (and hence very rigid) 15.75 (400 mm) wide bed with symmetrical V and flat ways and fitted, at extra cost for some markets, with a detachable gap When the gap section was removed, it allowed workpieces 29.25 inches (740 mm), 33 inches (840 mm) and 37 inches (700 mm) by 9.5-inches (245 mm) respectively to be turned on the standard faceplate. According to the spindle nose fitted and the type of front headstock bearing ordered, the maximum thickness of the workpiece turned using the gap varied between a minimum of 12 inches (305 mm) and a maximum of 13.25 inches (335 mm). For some markets the cast iron bed was not hardened, though the makers did offer, as an optional extra, a bed with hardened and ground steel ways to 60-62 Rockwell - the latter specification being fitted, it is believed to all UK-delivered lathes. Lubrication of the bed was provided for by a hand-operated pump mounted just to the right of the cross-slide ways - a shame that it relied upon the vagaries of the operator's attention and not an automatic system driven from the travel of the carriage as on so many competing machines.
In its basic form the lathe was supplied on separate headstock and tailstock plinths in cast iron, these being joined by a slide-out steel chip tray. However, as an option beds up to 80-inch (2000 mm) between centres could be supplied on a one-piece base in cast iron, the longer lengths, from around 158 inches (4000 mm) between centres having headstock and tailstock plinths with a third support in the centre.
Each lathe could be had in a choice of nine different between-centres capacities: 30 inches (750 mm); 40 inches (1000 mm); 60 inches (1500 mm); 80 inches (2000 mm); 98 inches (2500 mm); 118 inches (300 mm); 158 inches (4000 mm); 197 inches (5000 mm) and 236 inches (6000 mm). While not unusual for makers offering a single design of lathe in various capacities to state that the raised models and should only be used for the "light or medium-duty" turning of large workpieces, in the case of the DLZ range this precaution was not mentioned. However, a clue as to the maker's reticence on this point is the fact that, while the two smaller models were fitted with main motors of 7.5 h.p. (or optionally 10 or 14 h.p.) that on the largest machine was listed, officially, as being of 5.5 h.p. or, optionally, 7.5 or 11 h.p. thus limiting the chances of overloading the lathe on really big jobs.
Of box design with a full-size, removable top, the headstock held a spindle that was hardened, ground and lapped on all its bearing surfaces and bored through to clear 2.5 inches (63 mm). While the front bearing was usually an adjustable taper-roller type, as an option the makers offered, instead, a plain bearing - this being preferred by some users when the lathe was reserved for use in a toolroom. The No. 5 Morse taper spindle nose was hardened and could be had as either bayonet locking to DIN 55022 or an American-style D1 ASA-B 5.9 Camlock. All headstock gears were hardened and ground and each layshaft ran on ball races with those carrying sliding gears having ground-finished splines. Twelve spindle speeds were provided, in four ranges to a customers choice, these being applicable to all models and consisting of: 14 to 630 r.p.m.; 16 to 710 r.p.m.; 22.4 to 1000 r.p.m.; 31.5 to 1400 r.p.m and 40 to 1800 r.p.m. Lubrication was taken care of by a pump coupled to the input shaft, oil being sent upwards via a "check-that-it's-flowing" domed sight glass on top the headstock to a manifold from where it was distributed to the essential points by a network of pipes. The front bearing was fed directly, the rear by a wick that dipped into a an oil bath.
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Drive to the headstock was by four B-section V-belts direct from a motor adjustable up and down to set the belt tension by being foot-mounted on a pair of vertically disposed rails bolted to the back of the headstock. The drive passed into the headstock through a multi-disc, forward and reverse clutch and a powerful, brake of the external-band type - the latter being applied automatically as the clutch was disengaged., Above the motor, sealed safely in its own compartment, was the electrical switchgear, this whole unit being hinged and so able to be swung aside to give access for adjustment to the brake unit. Once power was switched on, electrical control of the spindle start, stop, reverse and brake was by a long control-rod set below and parallel to the powershaft with duplicated control levers to the right of the gearbox and (to ensure it was always within safe reach of the operator) pivoting from the right-hand face of the apron.
Screwcutting and power feeds were generated from a completely enclosed gearbox with control by levers - there being no open sliding tumbler by which means dirt and swarf could be admitted. Changewheels for driving the gearbox were contained within their own compartment and included (for the UK market at least)  a specially-marked "indexing wheel" to assist with the production of 2, 3, 4, 5 and 6-fold multi-start threads. Using the standard-fit 2 t.p.i. (or optionally 12 mm) pitch leadscrew, both a standard range of 32 English (Whitworth) pitches from 4 to 56 t.p.i. and 21 metric from 0.5 to 7 mm could be cut without in any way altering the changewheel drive -  though the 32 diametral and 9 module required the changing of four gears. Especially coarse pitches, set at sixteen times the standard range, were also available, these being generated by gears within the headstock with single lever bringing them into engagement; pitches provided were: 32 English from 1/4 to 3.5 t.p.i., 32 metric from 8 to 112 mm, 31 module from 2 to 28 and 32 diametral from 1 to 14. The makers also offered other sets of changewheels, to a customer's particular requirements, when special pitches had to be generated.   
Power sliding and surfacing feeds driven from a separate feed rod comprised 32 of the former from 0.070 to 1.000 inches (0.070 to 1.000 mm)  per revolution of the spindle and 32 of the latter at exactly twice as slow. At extra cost the makers could supply a fine feeds mechanism: sliding being 0.017 to 0.250 inches (0.006 to 0.0098 mm) per revolution of the spindle and, again, surfacing set to be twice as slow.
The compound slide rest was of substantial proportions with the cross slide (on UK-market models) of the full-length type two longitudinal T slots. The top slide could be swivelled 180° each side of central and fitted (for the size of lathe) with a rather prosaic triangular tool clamp - the aim being to persuade the new owner to specify something rather better. The "balanced" feed-screw handwheels appear to have been on the small size but, bearing in mind the care with which these lathes were assembled, and the smoothness with which they operated, this was almost certainly not a drawback. The cross-slide micrometer dial was fitted with three useful rotating radial spokes that allowed the turner to pre-set positions on repetition work. The bronze cross-feed nut was in two sections that allowed adjustments to be made to eliminate backlash.
Lubricated by an oil bath with a sight-glass to check the level, the double-wall apron was fitted with a drop worm for the engagement of the power sliding and surfacing feeds - this type of mechanism allowing an instant disengage even under the heaviest of cutting loads.
Standard equipment specified on machines for the UK market by the sole agents Stanton Machine Tools of Watford, was reasonably generous and included a complete electrical installation, a set of eight changewheels (5 mounted), a headstock reduction sleeve from 5 to 3 Morse taper, an extended cross slide, an ammeter, the fine-feed assembly, carriage longitudinal and cross-feed stops, two No. 5 Morse centres, the coarse screwcutting attachment, thread-dial indicator, grease gun, test certificate, operator's handbook and a set of spanners.
Extra equipment listed by the makers included: fixed and travelling steadies with roller-bearing or plain support arms, 12.5-inch catch plate, 20-inch faceplate, a 12-inch steel-bodied precision 3-jaw chuck, a 15-inch steel-bodied independent 4-jaw chuck (the steel-bodied chucks safe for the highest speeds), a 15-inch semi-steel independent 4-jaw chuck, complete coolant equipment, machine lighting with a 24-volt transformer, spare chuck backplates, 4-way and quick-set toolposts, single and double-holder rear toolposts and the appropriate parting-off tool holders to fit the extended cross slide, a longitudinal 4-position rotating carriage stop and a hydraulic copying attachment..