The Join Tolerance command allows you to adjust the tolerance used for joining database curves and surfaces.
Select Edit, Join Tolerance to open the panel. Uncheck the Use Default checkbox and enter a new value into the Join Tolerance text field, or simply begin typing into the text field and Use Default will uncheck automatically. Click OK to save the new value and close the panel, but note that there is no undo for this command. Click Cancel to exit the panel without saving any changes.