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Mahr Dti
Talyvel 1 Unit


On Site Services (Calibration) Ltd are a UKAS accredited calibration laboratory (No.7967) that offers calibration of Granite & Cast Iron surface plates & surface tables in conformance with the specified flatness tolerances in BS817:2008. View our Schedule of Accreditation here.

Surface table calibration considers 2 areas of flatness, identified as localised flatness (or local variation) and overall flatness. Local flatness relates to more sudden changes in the flatness of the working surface and therefore is likely to highlight the areas of the surface table that has been used and over-time caused a localised area to become "worn". On the other hand, overall flatness is the maximum error in the working surface from the highest point to the lowest point. 

For more information on the importance of surface table calibration please click here. 


A level surface table gives the perfect base for measurements to be taken, unfortunately for a variety of reasons it may have never been level or may no longer be level. Our skilled engineers will be able to correct this and are able to level a wide variety of surface tables or multiple surface tables together. 

For more information on the importance of a level surface table please click here.


The most important factors in metrology are accurate and reliable measurements. Unfortunately, when a surface table has been used it is likely that it might have become worn over time, this leads to the measurements taken becoming less accurate and less reliable. Even through correct care and use they can become worn beyond accepted limits, if it is deemed that these limits have been reached On Site Services (Calibration) Ltd are able to provide an on site reconditioning service. This service minimises the downtime of the equipment and allows customers to continue making accurate and reliable measurements as soon as possible.

This process is often referred to as resurfacing or re-lapping, the latter of this refers to the method that is undertaken. Our skilled engineers will precision lap the granite surface tables using a fine finishing compound that will retain the fine, close grained finish of the granite.

Upon completion of the lapping, the surface table will be calibrated and a certificate of calibration produced to verify the requested tolerance has been achieved.

Under certain circumstances it might be apparent that the surface table has deteriorated beyond economical repair. If this is the unfortunate circumstance, we are able to supply new granite surface plates and surface tables in a variety of sizes, both with and without frames to replaces your existing equipment. For further information please see our Granite Surface Plates & Tables page.


On Site Services (Calibration) Ltd
10 Cavendish Avenue
NG21 9NQ

Thank you for your enquiry.

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