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LORCH LA & LAN
Precision Toolmakers' Lathes
- and Types LL, LLG, LLP &  LLPF -

Lorch Home Page   Lorch LA & LAN Page 2

More information about Lorch Lathes is contained in various Manuals, Parts Lists
and well-illustrated Sales & Technical Specification
Brochures and can be purchased on-line here



Starting life in the early 1900s, the Lorch LL range of lathes was developed steadily over many years and even continued, with various suffixes (LLV, LLS, etc.) into the 1950s. Superbly made, to the highest standards, it was the smallest of the company's plain-turning precision toolmakers' models to have a version fitted with backgear and screwcutting (by leadscrew) and a tumble reverse unit. By retaining the usual long-travel top slide it was able to maintain the advantages of the ordinary "bench precision" (fine turning by hand) type whilst being a much more practical and adaptable machine. First listed as the Model LA it was to become, when fitted with better guarding of the gears and other small changes, the LAN. Retaining the same 65 mm centre height as the plain-tuning lathes in the series, the LA/LAN shared a number of headstock and tailstock components - but there the resemblance ended. Clustered together at the right-hand end of the spindle, the backgears were set beneath the spindle line, producing a neat, compact arrangement (as also used on the post-WW2 Myford 7 Series). With a 1 : 6 reduction, the backgears combined with a 3-speed headstock pulley and a  2800 rpm motor carrying a 2-step pulley to provide 12 spindle speeds starting at a rather high 75 and extending through 105, 150, 210, 300, 415, 450, 630, 900, 1250, 1800 to a maximum of 2500 rpm. Of 3 mm pitch, the  leadscrew (accurate to 0.02 mm in a length of 200 mm) was driven by changewheels through a tumble reverse mechanism; the full set of gears consisting of: 18, 20, 22, 25, 26, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 and 100t. Whilst changewheel guarding on the LN was non existent, the LAN was fitted with a very heavy cast-iron cover that shielded just the front section of the gear train.
Two bed lengths of 500 and 600 mm (19.7" and 23.6") were available to give between-centres capacities of 225 mm (9") and 325 mm (13") respectively - the former being by far the more popular and the latter virtually never seen. Although the carriage was guided by a V-way at the front and a flat at the rear (as distinct from the traditional flat-topped, bevelled-edged bed of the plain lathes) on this model Lorch used a special form of guide to retain the headstock and tailstock: the arrangement consisted of a front vertical face, together with an angled way at the rear that was cut into the underneath of the slot that ran down the centre of the bed. As the locking levers turned, they caused pressure on the angled side to push the units (forwards) into perfect alignment against the vertical surface.
Some early versions of the lathe had an ingenious method of providing an automatic knock-off to the carriage sliding feed: fitted to the apron were two handles - the shorter to select either "light" or "full" gripping and the longer to control the bronze clasp nuts. The clasp nuts were closed by the usual kind of snail-slotted cam plate with, in this case, the latter having a V-shaped cut-out in its outside face together with a peg, the end of which was connected by a spring to an arm of the end of the shorter lever. As the plate was turned to engage the nuts, a pawl, on the end of a pivoted bar connected to the disengagement button, was allowed to drop into the V-slot. With the lever set in the "light engagement" position - and the spring pulling on the cam plate - as the knock-off button hit the bed stop the pivoted bar pulled the pawl out of engagement and the spring rotated the cam plate, so disengaging the clasp nuts. Experienced users report that, whilst the automatic disengage would work reliably when using power sliding for ordinary turning jobs, for screwcutting it was better to forgo the luxury of the mechanism and leave the spring force disconnected (the full-engagement position). Unfortunately the rack-pinion gear engaged directly with the rack, instead of through reduction gearing, resulting in a very coarse feed along the bed.
As on some other Lorch models, an epicyclic reduction unit was available that replaced the gear normally carried on the end of the leadscrew; the effect was to provide an especially fine rate of sliding feed, a handy aid in getting a good finish on a long job.
Available with both lever and screw-feed barrels, the tailstock accepted the same collets as the headstock, though the latter appears was supplied without a Morse taper, this centre being carried, in the traditional way, as part of a solid collet.
Super-hard, ground and lapped the headstock spindle ran at first in adjustable steel bearings (early 1930s) and then, at some point towards the late 1930s, in bronze replacements. For collet use both types accepted either a simple drawbar or production-type lever-action quick-closer. The recommended countershaft speed was 1000 rpm with an allowable maximum spindle speed of a little over double that.
Beautifully constructed, the compound slide rest had a usual-for-the-type long-travel top slide and, happily, a full length cross slide that offered superior support even wear to its ways. The longitudinal travel of the top slide was 90 mm (3.5") and the cross travel 80 mm (3.1") -  a T-rest for hand work also being included as part of the standard equipment. In bare form the shorter of the two lathes in plain turning form weighed 41 lbs (18.6 Kg) and the longer around 44 lbs (20 Kg) with the screwcutting LAN being considerably heavier at around 75 lbs. Because it was possible to swap and adapt parts from a number of other Lorch models, the factory also offered a number of special versions including the rare LLPN, a type fitted with a headstock designed for thread chasing where the spindle slide in and out of its bearings under the influence of a master thread and follower. Further information about this process, together with details of other Lorch lathes on which it was fitted, can be found here.
Lorch was one of only a few manufacturers to ignored the long-time convention that turning a handle to the right would produced an inward movement of the cutting tool and, as a consequence, all versions of this lathe had right-hand thread or "cack-handed" screws as they were commonly known. One wonders, as a consequence, how many jobs were ruined in workshops where turners had to move from one make of machine to another during a day's work. After 1950 the company saw sense and the replacement for the LAN, the beautiful LAS, had conventional left-hand pitch feed screws.
Countershafts included the usual range of wall and ceiling mounted units and a number of "overheads" to power high-speed toolpost-mounted grinding and milling spindles. By the 1940s very much more compact, bench-mounted drives were available (though still not attached to the lathe) with a single post holding a large bearing, the drive pulley being on one side and the driven on the other. Unfortunately Lorch were never to offer an integral drive system on this class of  lathe and even the LAS retained the separate drive unit. Most of the models shown on this page were manufactured from the early 1930s until the early 1950s - the earlier  types of Lorch precision bench lathe can be seen here.

The Model LAN was the smallest Lorch "precision bench" lathe to be fitted with a conventional backgear assembly and screwcutting by changewheels and leadscrew. This example is a later model without the selectable low/high pressure grip on the leadscrew.

65 mm centre height Lorch Plain-turning LL No. 1 Lathe circa 1930s and 1940s with a bevel-edge bed and a No. 5 Compound slide rest

Lorch LLPN with the headstock arranged for "chase screwcutting" where the entire spindle was induced to move backwards and forwards under the influence of a Master Thread - or hob - held on an extension to its left-hand end. This restricted the machine to short - but very accurate threads - and was intended for use in the optical and instrument industries.

The Lorch Model LAN fitted to the wooden bench top No. 38 and driven by  the table countershaft unit No. 43a.
The overhead drive was employed to power grinding and milling heads clamped to the top slide - that shown being the Grinding Attachment No. 6.

Apron detail showing the large clasp-nut closing lever, the small lever to add spring tension to help the clasp nuts release

Inside the apron showing, in the centre, the spring that helped persuade the clasp nuts to release; on the right the lever
that pressed against the clasp-nut closing cam and, separately, the bolt-on carrier for the bronze clasp nuts.



The apron assembled--complete and ready to work

An immaculate Lorch LA of the 1930s complete with its cone of screwcutting changewheels. This model has the twin-lever system on the apron that allowed either "light" or "full" engagement of the leadscrew clasp nut - the former setting permitting the use of an automatic knock-off mechanism.

Lorch LA - a true precision lathe of only a 65mm centre height but fitted with full backgear, screwcutting and tumble reverse

Although the carriage was guided by a conventional V and flat way on this model Lorch used a special form of guidance to retain the headstock and tailstock that consisted of a vertical face together with an angled way cut into the underneath of the slot that ran down the centre of the bed.  The arrangement can be seen above. Note the 3 circles of division holes in the outer face of the largest headstock pulley.

The location method of headstock and tailstock can also be clearly seen in this photograph. Note the full-length cross slide.

Two-lever control of feed disengagement on an early LAN

Above and below: a late-model Lorch LAN

Continued here





E-MAIL   Tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools for Sale & Wanted
Machine Tool Manuals   Machine Tool Catalogues   Belts   
Books   Accessories


LORCH LA & LAN
Precision Toolmakers' Lathes
- and Types LL, LLG, LLP &  LLPF - 

Lorch Home Page   Lorch LA & LAN Page 2

More information about Lorch Lathes is contained in various Manuals, Parts Lists
and well-illustrated Sales & Technical Specification
Brochures and can be purchased on-line here