View Single Post
Old 06-28-2010, 01:43 PM   #10
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,370
Default Re: Bucking frame rivets

I've been bucking rivets for quite a few years in helicopter rebuild projects and have made all sorts of funny shaped bars to fit in all sorts of funny shaped places. The key on big rivets as Marco mentioned earlier, is the weight behind the bar. The offset in a non-straight shot has to be kept to a minimum for the hammer blows to get optimal effect. Also, the rivet head has to be held firmly against the materiel being riveted so that it doesn't get pushed back out. This is critical in the first few blows that expand the rivet then less so after expansion has taken place.

In aircraft construction we don't bother to form the buck tails like they did back in the hey day of steel construction. The buck tails are just flat and about as thick as half of the rivet's diameter. For authenticity you can mill a half round or pan head form into the bucking bar. Some body rivets had the waffle tails since that pattern would keep the squeezer dies from slipping during the original manufacturing process.

I think the reason a lot of the frame holes are so large after rivet removal is that the original expansion pushed the hole that way. Originaly the hole was only around .003" larger than the rivet shank diameter.
rotorwrench is online now   Reply With Quote