Wing Parts Prep - 4hrs

This work session included about six total hours.  Four hours were spent shaping and finishing (deburring and surface prep) of the wing ribs.  Both the nose ribs and the main ribs.  I used a home-made deburring tool and some 3M green pads to smooth out the edges on all parts.  I have ordered this deburring tool from Aircraft Spruce and it should speed things up for the next round.  Also did the .040 inboard most ribs.  I also spent about two hours straightening up the workshop and moving my large tools.  I moved the drill press and bench grinder off the assembly table and onto a separate table.  This is in preparation for the wing layup.  I should start that later this week.  That task will include setting up the wing spars and attaching the ribs to the intercostal angles.  First with clamps and then drilled for rivets per the plans.

Rib finishing - deburring and adjusting flanges to 90 degrees

I had to drill out the rib form for the lightening holes.  Here I am using the fly-cutter with my drill press.

Should start the wing assembly later this week.

Thanks for checking in.

Greg.

Bulkhead 12 and Tail Spring Support

Did some fabrication of the bulkhead 12 tail spring support today. About 2hrs on this piece.

It came out pretty good. Here's a pic. 

Going to make the other reinforcements tonight.

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.

Here's the score - or - Into the scrap pile...

The score is CX4 1 - Greg 0

I was doing okay starting the riveting of the center spar.  Then - the novice (me) messed up.  The rivet gun got away from me.  And I total destroyed the spar web piece (.040 sheet)

See the total destruction in the pic below:

So it's in the trash it goes (actually I'll save the pieces for scrap - but D***MN I'm mad at myself!  This is probably the first of what may be other screw-ups.  But I am not a happy camper...

I'll try to learn from this and move forward.

Grrrrrr!

Thanks for listening....

Greg.

How do you eat an elephant??

One bite at a time.

Building an airplane is a big project.  Many small tasks that result in a complex machine.

So - I took a few small bites tonight.  Marked out and drilled a bunch of rivet holes in my center spar.

About 40 holes drilled - twenty more marked out to drill and de-burr.  Some progress is better than not doing anything.

Going to finish drilling tomorrow morning and rivet complete riveting this piece.

Stay tuned and thanks for checking in!

Greg.

Center Spar - More Drilling and Rivet Preparation - 2 Hrs

Spent some more time drilling, de-burring, and generally preparing to continue riveting on the center spar.  It was warm today so with the door is open in the garage it was quite comfortable.  Should be warm all week so I hope to get more done on the center spar and start the wing spars.

I am being critical regarding my quality of drilling and spacing for the rivets.  Some mis-alignments.  Expected I suppose while learning new skills.  Before starting my CX4 project I had zero experience working with metal or drill presses, grinders, clamping etc.  This truly is a learning experience.  Guess it fits with the FAA definition of amateur built aircraft as stated in their documents.  As stated:

"Title 14, Code of Federal Regulations (14 CFR), part 21, section 21.191(g), defines an amateur-built aircraft as an aircraft “the major portion of which has been fabricated and assembled by person(s) who undertook the construction project solely for their own education or recreation.”

Emphasis on those last two words - "education or recreation"  It is educational - I am learning all kinds of new skills.  As for recreation?  Yes - I find it to be very relaxing and rewarding.  Until I screw something up.  Mis-drill a hole off center, buck a bad rivet, etc.  

In the following picture you can see my drilled holes include a couple of off center holes:

But I think those slightly mis-aligned holes are okay.  After all - I'm "building and airplane not a swiss watch" as I have seen it said on some other amateur built sites and message boards.

Here I am in a self taken pic de-burring the drilled holes.  I read somewhere that you should have pictures of yourself performing the work during the build process to prove you did work on your project during the DAR or FAA inspection of your build log. (of which I intend this to be) 

So here you go - for the record I am working on my center spar

De-burring the drilled holes that I will rivet later.

And just to keep it interesting - here I am lining up the center spar for drilling - probably this is the one that I mis-aligned while I was taking the self pic.  :)

As I move forward with the center spar I am considering using this as a "training piece" and trashing it at the end.  I have spent a bunch of hours on this part - and have learned but not quite perfected the skills and techniques yet.  So - If I mess up some more rivets or something I may just trash this work and start from scratch.  The raw materials I would have to trash includes two 35" pieces of aluminum angle, one 35" x 5 1/2" piece of .040 6061-T6 sheet, and two 35" pieces of 2024-T4 bar.  I have enough stock to redo.  And the angles are all reusable.  I'll make the call on wether to trash this piece or not later.  I would appreciate any feedback.  Take a look at my work as it progresses and let me know if this thing is a keeper or should I just use it as a learning experience...

And - Thanks for checking in.

Greg.

Riveting the Center Spar

Started riveting the center spar this Saturday.  After a bunch of practice (probably not enough) we started to commit to the process.  My son Greg helped and tried a few rivets too.  We did okay.  Maybe one or two to drill-out and redo.  But we are beginners after all.

Here is Greg trying out his new skills:

And here is some of the results:

May need to remove and replace that bottom right rivet in the above picture.  

Quite a few more rivets to buck.  Will continue later today and post results.

Thanks for checking in!

Greg..