Roland GR-640 User Manual page 208

Press [ ] and [ ] to position the tip of the blade
over the center of the lower-left crop mark.
Do not set the origin.
Crop marks cannot be read in the situations indicated below.
If any of the following situations occur, remove the material, and then reload it.
The left and right crop marks are slanted by 5 degrees or more with respect to
the moving direction of the cutting carriage.
The left and right crop marks are offset by 20 mm or more in the material-feed
direction.
The crop marks are separated from the blade protector by a distance of 15 mm