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Conwy Valley Systems Limited,

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The End of the Electro-Mechanical Slide Stepper


The Prior Scientific (formerly Swift) electro-mechanical microscope slide stepper has been one of the most reliable pieces of equipment in use in the oil industry. In its 40 years of production, over one thousand have been sold but there are no known cases of a replacement having been ordered, so production has been on a steady decline. Coupled to a drop in demand for petrographic analysis, limiting the number of new entrants to the market, it was perhaps not surprising that no-one noticed that production depended on one man, an ex-employee of James Swift, who manufactured them at home, on machine tools from the former Swift factory.


Unfortunately, he died recently and his widow apparently didn’t appreciate the importance of his work and of the tools cluttering up the place. Last year, it became apparent that orders could not be fulfilled and that the market did not warrant resumption of manufacture, as that now entailed re-establishing a manufacturing process.


Whilst this was inconvenient for those wanting to set up a new petrographic workstation, it was catastrophic for Conwy Valley Systems limited (CVS), a small company dedicated to reversing the decline in demand for petrographic analysis by enabling petrographers to bring it up to date in the digital data age and make it relevant to petrophysicists and engineers. CVS therefore set about making a replacement stepper, taking the opportunity to effect significant improvements on a 40-year-old design.


The new stepper has been built by Bangor University’s electronic engineering group (IDB). It comprises two precision miniature linear actuators fixed together to form an X-Y position controller. Each actuator is based on an 8mm diameter stepper motor driving a lead screw whose carriage runs on a linear slide. Precision and repeatability is assured without employing feedback sensors. The current version is coupled to its controller via a cable, but a cordless, remote-controlled unit is being developed. Position is under software control from a PC mouse and can be programmatically determined as either absolute or relative position.


Oil-IT magazine 2002, reproduced with the permission of the author



For further reading : Swift Polarising Microscope