TM 9-2320-280-34
e. Hole Countersinking.
NOTE
Some rivet installations in the body require that rivet head be
flush with the material surface, in these instances, countersunk
or flush head rivets are used.
1.
When using countersunk rivets, rivet holes must be countersunk with a tool having a 100taper so rivet
head will fit flush with surface.
2.
When using a hand-operated countersink, the hole must be tried with a rivet so the recess will not be
too deep or too shallow. It is best to use a countersink with a stop on it so depth of countersink can be
controlled. Typical countersinking dimensions for blind rivets are shown in table 22-3. The minimum
sheet thickness that can be machined for 100countersink rivets is given in table 22-4.
3. Do not remove edge of hole on blind side of joint.
100Countersunk Blind Rivets
010R.
MIN.
f. Blind Rivet Driving Practices and Precautions.
1.
Rivets should be inspected for proper installation. The grip length of each rivet is marked on top of its
head to provide positive identification. Use of proper grip length will produce a rivet installation where
locking collar is flush with top surface of rivet head. Tolerance limit on flushness is 0.020 in. (0.5 mm).
2.
For proper rivet installation, it is imperative that holes be properly prepared, tools be in good working
order, and rivets properly applied. When problems occur, the source of trouble could be in any of these
areas.
22-9
