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	Home Machine Tool Archive L athes for Sale Millers & Grinders for Sale E-MAIL tony@lathes.co.uk Bridgeport Millers Measuring Equipment Milling & Drilling Heads Cherrying & Slotting Heads Head Attachments Head Adaptors Bridgeport Home Page Accessories Measuring Equipment Quick-set Tooling Table Power Feeds Collets & Adaptors At Work Right-angle Drives Horizontal Miller Serial Numbers Round-ram Model Hydraulic Copying, NC and other Special Machines Before the advent of electronic measuring systems, milling machines commonly had two methods of precisely locating work - mechanical and optical. The mechanical system relied upon holders of some kind being fastened to the edges of the table so that accurate "length bars" - usually in inch increments - could be held within them. The end of the bar rested against a micrometer head that in turn was backed by a dial test indicator - thus providing a way, with a little calculation and the exercise of sensitive fingers, of highly accurate setting and measurement.

	The Bridgeport Precision Measuring Attachment for longitudinal and cross feed. The unit consisted of attachments to the edges of the table that held length bars, micrometers and dial gauges. The end measures were used to set whole inches, the micrometers for fractions of an inch and the dial indicators for ten thousandths of an inch - or their metric equivalents.

	Optical Measuring System for longitudinal and cross feed. Another pre-electronic era device for the precise setting of work that involved no mechanical contact - and so avoided wear and consequent inaccuracy. The unit bolted to the machine using a majority of existing holes - and was protected in use by a neoprene guard. The longitudinal travel was 20 inches, cross travel 9 or 12 inches, the magnification x17 and the reading accuracy 0.0001 inches on a direct, single line scale.

	The scale had just one line to read - and no vernier estimations to be made.


	Home Machine Tool Archive L athes for Sale Millers & Grinders for Sale E-MAIL tony@lathes.co.uk Bridgeport Measuring Equipment Milling & Drilling Heads Cherrying & Slotting Heads Head Attachments Head Adaptors Bridgeport Home Page Accessories Measuring Equipment Quick-set Tooling Table Power Feeds Collets & Adaptors At Work Right-angle Drives Original 1938 Model Hydraulic Copying, NC and other Special Machines