When pressmen check the caliper of plates, blankets and packing sheets, they usually use a machinist micrometer. Machinist micrometers are not recommended because of variations in readings that occur as a result of differences in the sense of feel and pressure from one pressman to another. It is also questionable whether one pressman can obtain reproducible readings. For pressroom use, machinist micrometers are not considered quantitative tools.
Ideally, pressrooms should be equipped with table model dead weight or spring tension micrometers to measure the caliper of plates, blankets and packing sheets. Such micrometers have the advantage of allowing measurement at the center as well as at the edges, of blankets and paper, while also eliminating the human element from such measurements.
Measurements should be made with a 9/16 inch diameter anvil. The 9/16 inch anvil corresponds closely to packing gauge measurements on press.
The above was reprinted with permission from GATF Technical Services Report.
Graphical Arts Technical Foundation
200 Deer Run Road
Sewickley, PA 15143-2600
Phone: (412) 741-6860
Fax: (412) 741-2311