While I am not sure what plane we are disscusing, however the best way to make sure that your CA hinges are equal in both surfaces is to insert a T pin in the middle of the hinge and push it into the wing or aileron until it is touching the pin. Leave all the pins installed and install the hinges into the other surface so that it is touching the pin. Once you have the surface installed so that all the hinges have the pins touching both surfaces, you can remove the pins. At this point you can close the gap if needed and then glue them in with thin CA. Make sure that you do both sides of the hinges with the thin CA. Be careful not to use to much glue. Once you have finished glueing and it is dry, give the surface a pull test to make sure that your work is correct. Good Luck, Dave