### Straightness Feature Control Frame Information

A Straightness FCF has no datums, so the material condition modifier (MMC or LMC) applies only to a required cylinder feature. When evaluating Straightness on a cylinder, you must take at least three levels of probe hits. The more levels of hits taken, the better the evaluation of the cylinder's straightness.

A Sample Straightness FCF at MMC

When you dimension a cylinder's Straightness at material condition, the Advanced tab of the FCF will display a DF axis in the True Position area to allow the user to enter the size tolerance for the bonus calculation. See "GD&T - Advanced Tab".

Sample True Position area in the Advanced tab showing the DF axis

Note: Straightness on any feature other than a cylinder does not allow a material condition modifier.