Well established by the 1920s - with the Models "1919" and "1920" in sizes 1, 2 and 3 - Aciera of Le Locle, Switzerland offered a number of high-quality miniature drilling and tapping machines intended for the homological, instrument making and similar industries. Of these, the better known are the No.6, No.10 (described below) the E.3 and E.3.T-tapper the 20,000 r.p.m. Servo 7150 and the largest of the smaller sizes, the 13 mm-capacity Type 13
Built in both an early "rounded" style and later with particularly neat-looking more angular lines, the miniature Aciera drills-cum-tapping machines were offered as two models, the No. 6 and No. 10 - the numbers representing the maximum drilling capacity in steel. Both could be supplied as either simple drills (6T and 10T) or, as the 6E and 10E for tapping - these having a control switch marked with an extra position - "Tapping" - and a double contactor that reversed the spindle direction automatically at an operator-set point. When tapping, the permitted revolutions were marked on the speed chart in red. In addition, an ingenious controlled-pitch tapping model was available that, with a gear housing attached to the quill and interchangeable pitch leadscrews, facilitated making high precision threads into thin or soft materials. A further development was a special model with a form of pneumatic-hydraulic control for use in batch manufacturing or long runs.
Arranged in a conventional way, with an electric motor at the back driving, by a narrow V-belt, a multi-groove pulley at the front with 8-steps on the No. 6 and six on the No. 10, a particularly wide choice of speed ranges and motors was offered. Some 2-speed motor versions of the No. 6 had sixteen speeds spanning 350 to 12,000 r.p.m. - while a similarly specified No. 10 could have as many as twelve from 175 to 10,000 r.p.m.; the speed ranges and motor availability for both models are shown separately below. Early tapping machines are known to have used a different drive with a flat belt and, generally, two fewer speeds in each range.
While the upper section of the belt-drive guard was arranged to hinge open for the changing of speeds, it did not, unfortunately, automatically release and tension the belt; instead, the lower section had to be manually unlocked by releasing a bolt. Once slackened, the assembly could be slid forwards, the speeds changed, and then pushed back to tension the drive and the bolt retightened.
Rotating in high-class, adjustable ball races, the spindle was held in a hardened and ground quill that ran in a honed bore in the cast-iron body. Quill movement - the No. 6 had a travel of 50 mm, the No. 10 twice as much at 100 mm - was by rack-and-pinion gearing under the control of a single lever, adjustable for length by being slid through its mounting - and also for its initial setting by te use of castellated faces on the inner and outer sections of the mounting boss outboard of the graduated depth-control drum. Drilling depth was controlled by a vertical shaft whose end finished in a knob positioned to the left of the chuck; the shaft was locked by a through bolt and the travel shown on a scale, graduated with both inch and mm ruler marks, on the head's front face. No.6 Drilling machines had a spindle nose with a taper to DIN 238-B12A fitted with a precision chuck while built-in 24-volt light unit - neatly integrated into the head behind the drill chuck - was a standard and useful fitting. The No.10 model could, as an option, have a spindle fitted with a No. 1 Morse taper - in which case the quill was machined with a knock-out slot.
As the drill was intended to be as accurate and as rigid as possible, there was no rise-and-fall table; instead, for a coarse setting, the whole of the drill head was arranged to travel (for 200 mm on the No. 6 and 300 mm on the No. 10) up and down a large-diameter, steel column, machined with a rack into its front face. Adjustment of the head's position was by a crank handle inserted into a square socket on the front face, a clamping lever being positioned to the right, at the rear. The crank did not engage the rack directly but instead - to prevent the head falling under its own weight - through worm-and-wheel gearing with it's usual "self-locking" properties. The rather unusual positioning of the head-lift control on the front face may have been to allow easier access when the drills were mounted in gangs of up to six at a timer on a common base - these versions being known as the K Type.
All versions of the drill were available for mounting on the customer's own bench with a plain table (Types 6T1s and 10T1s) or with a coolant trough (Types 6T1 and 10T1) - the final digit indicating one machine on its own base. When fitted to the maker's sheet-metal stand the type designation changed to 6K and 10K and, if ganged up in a line on a common cast-iron base, the suffix was changed to match fitted e.g. four in line for bench mounting with a coolant trough would been the Model 6T4 and on the maker's stand 6K4 - the same system being used for the Model 10.
Tapping versions required care in set-up and operation - and before using one reference to the operating manual is highly recommended.
Other makers of miniature drilling machines included, over many decades: Worner, Jones and Shipman, Pollard, Meddings (MB10), Servo, G.Boley, Bergeon, Leinen, Oldak and Apex, Derbyshire, Micromecchanica, Flott (TB6), Sloan & Chace, IME, Hauser, Dixi, Cataract, Nora and Precise..
The writer seeks high resolution photographs of all small Aciera drilling and tapping machines. Can you help? If so, do please email