Roland GR-640 User Manual page 26

Material Types and Blade Adjustment
It may be necessary to adjust the amount of blade extension for some types of
material, such as material with thin carrier paper. If you are not able to obtain
stable cutting results, changing the amount of blade extension can yield better
results. For more information, refer to the pages indicated below.
General Guide Regarding Cutting Conditions
Changing the Blade Force
Changing the Cutting Speed
Adjusting the Cutting-in Amount
Performing a Cutting Test