Bob Spikings was looking for a project when he happened across a book by Len Mason, Building a Small Lathe, in the library. Later he bought the book and started the project, which he continues to work on between other projects.

Len Mason described the design, saying, because a lathe is small in size and capacity, it does not have to be primitive. His complete design includes screwcutting gearing and back gears, although a simple lathe is an option.

He says: “A fair proportion of commercially produced miniature lathes do not provide facilities for screwcutting for instance, yet a lot of screwcutting jobs are well within the capacity of a baby lathe to undertake. You can carry out screwcutting on the lathe described here, but with a somewhat restricted range of possible threads as compared with a full-size tool room lathe. This is because of the size of the lathe itself; not because the lathe would not be able to cut extra fine or coarse threads, but because there is just not room to accommodate the size and number of change wheels required in a train to produce the gearing necessary for pitches of threads at the ends of the range... Even so, all the conventional pitches of threads between 4 and 48 t.p.i. can be screwcut, which should cover most requirements.”

Regarding the building: “there are no highly skilled or tricky operations involved. All the work is of a straightforward nature. It is generally claimed that you need a lathe to build a lathe, and this is true. Access to a lathe for many of the jobs is essential. The lathe shown was built entirely on a 3 1/2in. lathe and all the turning has been successfully carried out on one smaller than that. When it comes to the actual assembly of finished components, all the fits and locations are adjustable for the sake of the accuracy of the finished job. The final accuracy is dependent on the amount of care you are prepared to take over it.

“All the material comes from stock sections of mild steel bar and strip, and no castings at all are required. In many cases odd small items can be produced from scraps and ‘short ends’ from the workshop scrapbox.”

Specification:

Centre height: I 3/4in.

Distance between centres: 8 in.

Maximum swing on faceplate: 4 in. diameter.

Swing over saddle: I 7/8in. diameter.

Overall sizes: length 20 in., width (cross slide in) 7 in., height 5 1/2in.

Mandrel: 1/2in. diameter, screwed 1/2in 16 t.p.i., bored 7/32in. through. No. 0 Morse.

Bearings: Split cast iron or bronze; adjustable.

Tailstock : Screw feed, bored 7/32in. through. No. 0 Morse.

Compound slide rest for 1/4in. square tools in adjustable tool holder.

Lead Screw: 1/2in. diameter, 8 t.p.i. Back Gear Ratio: 6.25: 1.

Drive: 1/4in. round belt, 3 speeds.

Weight, with faceplate: 21 3/4Ibs.