Some Thoughts on Riveting . . .
The Second Time Around
by Dave Nicholson, EAA 123720
Newton, NJ
(submitted by Fast Fred)
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In all the chapters concerning riveting in
military or civilian manuals, they depict a nice clean hole in the metal and a snug fit on
the rivet shank. They also state "remove the old rivet by drilling off the head only,
then tap out the shank with a punch. If the hole is oversize, drill out to the next size
rivet."
This all sound neat and proper, but what they do not tell you is
that in upsetting the original rivet, as the "button" is being formed, the shank
is swelling and so is the hole, so no matter how diligent you are in removing the old
rivet, you will still have an oversize hole.
Granted, a lot of times you could still produce a satisfactory
job of riveting with a slightly oversize hole. As for "drill it out to the next
size," what if after drilling you do not have the required edge distance? Call in the
Marines?? This time cal in the Navy.
Just before Pearl Harbor, while working as an aviation metalsmith
at the Naval Air Station, San Diego, I was taught the following, so you may say this bit
of information is courtesy of the U.S. Navy.
On many of the repair jobs, rivet holes were found to be oversize
by varying degrees. With marginal edge distances, a method was devised to use standard
size rivets and swell the shanks to fit the holes. Obviously, this required that more
shank protrude beyond the plates that the usual 1-1/2 D.
Now, we all know that it is next to impossible to use that loner
shank without bending it over. The Navy devised a tool to overcome that difficulty. This
tool, when placed over the longer shank rivet, will be as shown in Figure 1. The first
action is drawing the palates together while upsetting the shank as shown in Figure 2.
This drawing action is continued until the tip of the tool bears
against the metal sheets, ensuring a tight fit between them. Due to the dimensions of the
tool, there is still enough shank protruding to produce the proper size
"button", after the next operation which is "normal" rivet driving
(Figure 3).
Start with a 5/16 aircraft bolt. Cut off the head and drill the
end corresponding to the size rivet to be used, 1/8", No. 30 drill; 3.32", No.
40 drill. Drill slightly deeper that 1-1/2 D. Now grind a drill to produce a hole of the
dimensions, shown in Figure 4. Run this into the previously drilled hole until you are
sure the bottom of the hole is flat. Trim off the end to ensure that the holes 1-1/2 D
deep. Now polish the inside of the hole to free it of drill marks which may inhibit
withdrawal from the rivet shank after the drawing operation.
Obtain a block of steel approximately 1"x2"x3" or
an dimensions that suit you provided it has enough weight to act as a bucking bar.
Naturally, the larger the rivet, the heavier the bar. Bore a hole in the end of the bar
close to a corner to accommodate the bolt shank and braze the bolt to the bar. At this
point you may elect to harden the tip of the tool (see Figure5). This tool has many times
proved invaluable to me. Hope your results are the same. |
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