email: tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools Sale & Wanted
Machine Tool Manuals   Catalogues   Belts   Books  Accessories

Precision "Home-made" Lathe


Although the background to this "home-made" miniature precision lathe is not known, it looks to have been constructed during the 1940s or 1950s. Perhaps "home-made" is the wrong description and made-on-the-night-shift-when-the-boss-was-not-looking could be more accurate. Built to a very high standard with pleasing details - for example all slot-headed screws were fitted flush, being set into countersunk holes - the design was also ingenious and the builder obviously a person of considerable talent.
Either machined from the solid or fabricated (details are not yet known), the wide, flat-topped bed with its unusually wide V-shaped edges was made in a form reminiscent of that used on the Hardinge HLV toolroom lathe. The leadscrew, mounted under the bed on its centre line, was held in bearing housings screwed in place between the walls; rather cleverly, the bearings blocks were extended downwards to provide mountings for the clamp-on bed feet. To locate the tailstock a T-slot was provided, down the middle of the bed's top surface - though not full length, it was just long enough to allow both centres to touch. At each side of the T-slot a V-shaped grove was machined, these being used to align the tailstock whose base edges were machined to fit - a most unusual and possibly unique method, though one that might have been prone to wear as swarf fell into them.

To accurately locate the headstock, the end of the bed was formed with a flat top and bevelled edges, the shape being similar to that used on the full bed length of most traditional *bench precision lathes.
An outstanding feature of the lathe was its "double apron"; this, in the form of a welded fabrication (or possibly machined from the solid),  passed beneath the bed to form a bridge piece that joined the front and back of the saddle, an arrangement that provided great rigidity and as found on that other home-made English lathe, the Petrie as well as the popular and long-lived  Boley Type L (of the 1920s and 1930s) and Rolls-Royce and Toyo ML1 machines.
Mounted in the centre of the bridge was the leadscrew clasp nut, its detailing again imitating Boley design with a centrally mounted engagement lever and a handy and very effective push-button release. With the carriage propelled along the bed from a point immediately below the toolpost, the shortest possible and stiffest route was created between the two points.
Screwcutting was by changewheels, the gears being carried on a single slotted arm with the drive passing through a tumble-reverse mechanism. The latter, instead of being mounted on the usual difficult-to-engineer plunger-located bracket were fitted to the end of an arm pivoting concentrically with the changewheel bracket, it only being necessary to slacken a nut to swing the gears to give a left or right-hand feed, or neutral. Changewheels appear to have been held in place by the traditional Boley method of screws whose undersides fitted into countersunk holes in thick washers; unfortunately the builder did not go on to slot the washers and so allow them to be slipped out after just slackening the screws and allowing the changewheels to be slid off.
Appearing to be made from a casting (though it might well have been machined from the solid), the headstock carried a threaded-nose spindle machined to take draw-tube tightened collets; the 3-step V-pulley, taking a "Z" belt, had epicyclic speed-reducing gears held within its largest diameter - an especially neat and effective way of obtaining backgear and a system found on such widely diverse machines as, for example, the inexpensive American AA (Craftsman 109) and superb Swiss-made Mikron.
Adjusted to the bed by a tapered gib strip positioned at the back, the carriage was fitted with a well-made compound slide rest with the top slide located in a 360 T-slot and its front face bevelled and engraved with degree lines to set the swivel angle. Neat, angle-faced, zeroing  micrometer dials were fitted and, like the American Pratt& Whitney bench precision lathe, the feed-screw end support plates were secured with four rather than just two screws, a seemingly insignificant change yet one which was intended to reduced "spring" and enhance the operator's feel of what the cutting tool was doing. Each end plate was also of an unusually involved design with (instead of just a hole through which the feed screw could pass) a boss formed integral with the plate and extending below it - an assembly that would have been most awkward to machine from the solid
With the section beneath its spindle hole the only cosmetically unfinished part of the lathe, the carved-from-the-steel tailstock could not be set over for the turning of slight tapers but was locked to the bed by an eccentric cross shaft with integral handle and fitted with a powerful "split-barrel" spindle lock.

*Including: a list pf precision lathe makers with links can be found here



email: tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools Sale & Wanted
Machine Tool Manuals   Catalogues   Belts   Books  Accessories

Precision "Home-made" Lathe