PRI ¢IS attachment fitted to the stage carriage, thus eliminating the necessity of a spring return. One division on the thimble gives 1 /~m movement of the carriage. A vernier can be engraved along the side of the stage with a reading plate attached to the carriage. It is also possible to fit a transducer to the opposite end of the micrometer using a suitable attachment for further verification of the carriage position.

Five different models are available with accuracies of + 0.75 to + 2 pm depending on the model.

Constructed of high quality hardened stainless steel, with recirculating ballscrews, a choice of two body widths are available. The standard resolutions are 1 /~m, 10 #m and 100/zm in half step mode. Also available is 0.1 /Jm resolution.

Position accuracy is within 1 /Jm for 100 mm travel and 2 #m for 500 mm travel. The ML motorized range can be supplied with stepping motors or dc sero-motors, plus tachometers and encoders as required.

Unimatic Engineers Ltd, 122 Granville Road, Cricklewood, London NW2 2LN, UK

Company for precision measuring equipment A new company has been formed to provide the UK market with a comprehensive range of precision measuring equipment. The company is a combination of Fowler and NSK.

Fowler-NSK's products include high quality micrometers, calipers, indicators, test indicators, rules, gauge blocks, vices, optical equipment, and other precision measuring instruments.

Demonstration facilities at the company's Letchworth, UK, base are available to allow the end-user to see the products in use and to understand fully their capabilities. Training sessions on how to service the complete range of products are also available.

The entire product range, including electronic digital micrometers with computer interfaces, is detailed in the company's latest 280 page brochure, which is available free of charge.

Fowler-NSK Ltd, 6 Ascot Industrial Estate, Icknield Way, Letchworth, Hertfordshire SG6 1TD, UK

Compact internal grinder works under full CNC The high precision SI4/AI CNC internal grinding machine supplied by Wm Watts is equipped with an easy to programme Marposs E24 CNC controller. As a result this machine can be used economically on single part and small batch work, as well as on large quantity production.

It is very flexible in use, cylindrical and tapered bores can be ground by oscillating and plunging methods, Stepped bores, internal and external faces, as well as radii and chamfers, can be ground to programs entered through the in-built keyboard or to a stored program entered through a V-24 interface. Up to six surfaces on any workpiece can be ground during one programmed cycle.

The machine has a conventional layout with a cross-slide mounted headstock carrying the workpiece spindle and clamping unit. At the other end of the bed another cross- slide on a saddle carries the grinding spindle. Transverse movement of the headstock (U-axis) is 200 mm whilst that of the grinding spindle (X-axis) is 120 mm. Longitudinal movement of the grinding table (Z-axis) is 560 mm.

As a result the machine has the ability to handle a wide range of

work, Internal diameters can be ground as small as 5 mm and as large as 250 mm. External diameters up to 200 ram, and lengths UP to 250 mm, can be ground although the machine will allow diameters of 500 mm to be swung under the splash guard.

Workpieces can weigh up to 180 kg, including any clamping devices, and for bar-type workpieces there is a 56 mm diameter hole through the headstock.

Rotation of the workpiece is by 16 kW variable speed AC motor driving through a two-speed gearbox which gives speeds in the ranges 35 to 700 rev/min and 140 to 1400 rev/min. The direction of rotation is reversible.

Feeds in the three axes are driven by DC servomotors through high- precision ball screws using high resolution resolvers to provide the feedback. In the two transverse axes (X and U) the infeed increments can be as little as 0.5 pm steps. In the Z- axis the increments are controlled down to 1 /~m steps. The repetitive positioning accuracies for diameter and length are both guaranteed within 1 /~m.

Wm Watts Ltd, PO Box 27, Abbeyfield Road, Lenton Industrial Estate, Nottingham NG7 2TE, UK

Positioning accuracies for diameter and length are guaranteed to within 1 #m on the CNC internal grinding machine from Wm Watts

PRECISION ENGINEERING 103