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Map measure of the month: the Sakurai centimetre curvimeter

Sakurai Curvimeter
Sakurai Curvimeter

This Japanese made measure is simple and attractive but has lost the capability for very accurate measurement over the past couple of decades.

SAKURAI brand and logo

Sakurai were founded in 1950 in Hamamatsu, Shizuoka-Prefecture, Japan. The company first focused on automotive parts and having established a reputation with their model 800 Rotary Milling Machine and an automatic multi-spindle head changer Turrex machine, they built a further plant in Funaoka in 1970 and at Hosoe 1989, before moving their head-office to Funaoka in 1997. Today, they specialise in special-purpose machine manufacturing and their lines include parts for aircraft, automobile and motorcycles. The company has subsidiaries in Ohio, USA (established 2000) and Hanoi, Vietnam (established 2002).

Sakurai Curvimeter in case
Sakurai Curvimeter
Sakurai Curvimeter
Sakurai has a plain back

This is a simple measure with little in the way of embellishment beyond extensive knurling on the handle which improves grip during use. The rear of the case is entirely free of any markings or engraving, other than the pivot pins for the tracking wheel and central internal gearing. The front of the metal case outside the dial is likewise free of markings.

The polished stainless-steel handle is 70mm long with a 5.5mm diameter that tapers at the very end, to 4.85mm. This handle has a fine internal screw thread and screws onto the case. The polished stainless steel case measures 48.7mm, excluding a small steel tracking wheel at the base, and a 7mm threaded part on to which the handle screws. The measure is 8.41 mm at it’s thickest point. It has a glass crystal, slightly marked on my example, behind which there is a matt silver dial face. There is just the one darkened metal needle, which rotates around a measuring scale of 0 – 100cm, with numbered 10cm increments, and unnumbered five and single cm increments between these. The centimetre measuring scale is indicated by CM on the uppermost part of the dial. Below the needle are the words TOKYO / SAKURAI. Outside the circular measuring scale, at the base, are the words MADE IN JAPAN TOKYO SAKURAI. Note that Tokyo is nowhere near Hamamatsu, Hosoe or Funaoka. This is likely because Tokyo had by then become a recognisable name, as one of the trading centres of world economics.

Centimetre dial face on Sakurai Curvimeter
Centimetre dial face on Sakurai Curvimeter
Fine toothed tracking wheel
Fine toothed tracking wheel
Sakurai Curvimeter
Sakurai Curvimeter

The 53g measure is well balanced and comfortable to use. Rolling the tracking wheel along a line, a road, a path, a drawing etc, rotates the needle around the dial and indicates how many centimetres have been tracked. In operation, the wheel tracks smoothly without noticeable internal resistance or noise. Tracking a measured 100cm (1000mm) indicates 101.5cm (1015mm), an error of 1.5%. This slight discrepancy may be down to minute wear on the slightly toothed tracked wheel. Or perhaps it was always there.

Two part plastic holder for Sakurai Curvimeter
Two-part plastic holder for Sakurai Curvimeter

The Sakurai Curvimeter comes in a plastic case formed of two parts. A transparent deep-blue base, in which there are moulded plastic lugs into which the curvimeter nests, and a loose press-fit clear plastic lid.

There are two words on the two-part plastic case- CURVIMETER in the top left corner of the lid. The blue bottom half has the words MADE IN JAPAN moulded into it bottom right.

A label attached to the reverse of the case indicates the supplier of the instrument, complete with Swiss phone number: “supplied by Geo-Systems CH (03) 365-6298“. This likely refers to Leica Geosystems, based in Switzerland, who both made and supplied products and systems for surveying and geographical measurement. This was their company identity from 1997 to 2005, after which it was acquired by Swedish company Hexagon. This potentially provides us with a date range for the Sakurai Curvimeter shown here.

Geo-Systems label

There is another version of the Sakurai Curvimeter. That comes in a red plastic case and has front and rear measuring dials. The front is identical to the measure shown here, capable of measuring centimetres, plus a dial with 1:30 000 and 1:50 000 scales on the other side. That measure may feature as Map Measure of the Month in a future post. Three Points of the Compass has had a closer look at many other measures and links for those can be found here.

Sakurai Curvimeter
Sakurai Curvimeter

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