Riveting - "Practice makes Perfect" - Does it?

Regarding my last post on hosing the center section spar - I want to learn from the experience.   Allow me to examine what happened prior to my failure.

I did a fairly good job at producing the parts.  The extruded angles were cut accurately and prepared according to standard practice. (deburring etc)  The 4130 steel straps, probably the hardest material I have ever worked with in my limited experience, were fabricated with a level of accuracy and quality that surprised me.  I had doubts in my ability to cut the web material (.040 sheet) with a straight line but the result of my efforts were also a surprise to me.  My confidence was booming after preparing these pieces.  

My drilling of holes for rivets and bolts after clamping the pieces together was at first challenging.  I improved during the process and any misalignment of holes was acceptable so I continued.  Cutting and shaping the intercostal angles was the hardest part for me.  But I did develop the skill and formed those too.  

Now we get to the riveting part of the story.  Yes.  I mucked it up.  But I'm going to learn this skill as it is something that I need to do.  And there are some other bucked rivets in the CX4 that I must contend with.

So I took the center spar out of the scrap heap and completed riveting it.  Even though it is not airworthy quality it will serve well as a training/test piece for developing my riveting skills. 

I did it.  Rivets set.  Some good, some not so good, but my technique improved and the good ones outnumbered the bad ones as I went along.  Here are some things I learned/did regarding bucking rivets:

1 - I watched the EAA video several times.  http://eaavideo.org/video.aspx?v=1200014906001

2 - Found that when the spar was clamped to the bench it was easier and I had better results riveting the top rivets.  The top row was easier to set properly.  I think this is because there is some "flex" in the material when it is clamped to the bench.  The bottom row rivets were harder to buck and I made more mistakes.  I think when riveting the lower row the spar was too rigid and didn't give much tactile feedback to me through the bucking bar or the rivet gun.

3 - Make absolutely positively sure the rivet gun and bucking bar are 90 degrees in all axes.  This is VERY important for passable results.

4 - Keep a firm grip on the rivet gun but do not choke it.   Too much of a grip and you loose control and feel for what is happening as the rivet is set.

5 - I have a whole new respect for those guys that build with bucked rivets like RV's and such.  

6 - Practice Practice and practice some more. 

Thanks for listening - 

"Illegitimi non carborundum"

Greg.