Beginning the machine countersinking of the right F-1255 longeron. Paper prevents metal flakes from getting in the fuselage.
The countersink bit was set for the depth of the dimples the Cleaveland 120 degree dimple dies create in the side skin material. The countersink cage was adjusted so the depth of the countersinks would allow a dimpled test strip to set flat on the longeron. This ends up being about a click or two deeper than a CS4-4 rivet would normally require being flush. The air to the drill was adjusted WAY down so the countersink bit spun slowly and Boelube was used on the tip of the countersink bit for every hole. One minor issue came up when attempting to countersink the rivet holes in the area of the F-1234 canopy base … the overhang of the canopy base interfered with the countersink cage preventing it from sitting flat on the longeron, so the canopy bases required being removed from the longerons.
The 120 degree machine countersinking of the right F-1255 longeron's rivet holes almost completed.
As with the right longeron, the shrapnel shield was used and the F-1234-L canopy base was removed so the countersink cage could sit flat on the left longeron.
Beginning the machine countersinking of the F-1255-L longeron.Almost finished with machine countersinking the rivet holes on the F-1255-L longeron using the countersink cage outfitted with a 120 degree cutting bit.
Now that both longerons have been machine countersunk for flush rivets, the inside edges of all those drilled holes need to be deburred … so that will be first thing on the to do list during the next work session.