I know that putting a crosshatch on a pork chop won't increase its flavor but I like the presentation. Generally, I either rotate my chops too early or too late, resulting in torn meat or no crosshatch. How can I tell when is the right time to rotate the chop to achieve the crosshatch?
First, make sure your grill grates are brushed well to remove debris so that the food has complete contact with the grates. After preheating the grill use a clean old towel to wipe the grates with a light coating of oil. Additionally, a thin coating of oil on your pork chops or other protein item will be beneficial.
Once you've placed the meat on the grill it's really just a matter of paying attention to the meat. Don't try turning too soon or you'll tear the meat and leave the grill marks behind. If the meat resists, leave it alone. It will release itself from the grill when it's ready to be rotated for the cross-hatch marks or to be turned over.
Of course there is no need to be concerned about grill marks on the second side as only one side will be the "presentation side" and the second side will never have marks as good as the first since there will likely be small bits of food debris keeping it from having complete contact with the grill.
Presentation side for other items would be the flattest surface (such as the skin side of a skinless chicken breast) or the nicer looking side (flesh side of a fish fillet).