Close-up shots of HS?

[txaviator]

Does anyone have any close-up photos of the horizontal stabilizer? What I am looking for is detail of the rivets. I know this sounds strange, and is not -9 specific (since I am building a -9).

Let me try to explain.....As mentioned in a previous thread, I am paranoid that my rivets look a little too deep. When I glance down the top or bottom skins of the HS, I see uniform little indents around the rivet head itself. Nothing terrible, and not a result of too much air pressure on the rivet gun. Not 'smilies', and not the size of the rivet gun set. As I look at the rivet lines, every single one is uniform in this charecteristic I mention. Almost as if the rivet was set down a little deeper than the dies allowed for, although the dimples were obviously all the same, and I didn't over-beat the c-frame. Instead of seeing a perfectly flat surface with tons of little flush rivet heads, I see a surface where around each rivet head there is a slight indention; as if the dimple dies were just a hair too deep.

It's hard to explain, and may be the exact same on other planes. I have seen tons of unpainted RV's, but all of them prior to beginning my empennage therefore I never thought to look. On the painted ones, maybe the paint takes away some of the effect? It could be the shiny aluminum being dimpled and riveted, playing tricks on my eyes.

I have been through every website I can find, trying to ease my concerns. I have yet to find a close up, kind of angled shot, which will allow me to see other people's riveting. Once I get my new digital, I will try to post photos. Again, it is not real noticeable (and perhaps tough to photograph) but something I would like to put behind me as far as worrying (and I may be worrying about something that is common on EVERY RV)?

Thanks for any help.

[ClayR_9A]

I THINK I know what you're talking about because I've noticed it and have looked at lots of other planes to see if I can tell the difference in the dimples.

I have a feeling that your dimples might not be 'crisp' enough. Either that, or you might be hitting them TOO hard. I noticed a difference between my dimples done on the edges of the skins with a pneumatic squeezer and the ones done with a c-frame. I also noticed a difference between my dimples that were done on a table that had some 'flex' in it, and those done on a table that was extremely solid.

I found that the c-frame dimples done on a table without any flex were the best. They were nicely formed and the skin around the dimples was very flat. The dimples I did on the edges with my pneumatic squeezer seemed to cause the edges of the skin to be somewhat 'wavy' and the rivets had the indents around the rivets.

I know this all sounds like black magic, and there are probably other qualities that affect the dimple... like the dimple dies, for instance.

Try experimenting on a scrap piece of aluminum. Put your c-frame on a cement floor and make a couple of dimples. Then put it in the center of a folding table and look at the difference! Try different hammers and hitting both soft and very hard to see what works the best.

-Clay

[txaviator]

I am certain that my dimpling was done "by the book". I was using a stout table, and didn't use too much force with the hammer/dies. We had a very lengthy discussion on dimpling in my builder class, and I am certain they are correct. Also, I was using brand new dies for the process, and they are lined up perfectly with one another.

I may just be 'seeing things', but a photo from someone else's project would help me to confirm or dispell my paranoia.

Again, it is nothing that looks "bad", it's just that rather than a perfectly flat surface with jillions of little flush rivet heads, it appears every rivet is sunk just a fraction too deep, based on the dimple itself. You "see" dimples rather than a perfectly flat surface. By the way, the rivets along the spar are the same way, so this is also leading me to believe I am just seeing things. Granted, I know that the spar dimples are different since I had to countersink with the cage tool into the spar itself (after dimpling the skin), but they also look the same. Whether I used the pneumatic squeezer or the Sioux 2X rivet gun....all the same.

Anyone have any close-up photos? Maybe angled, looking from one tip, kind of down the length of the HS? Again, it surely doesn't matter what model of RV...rivets and dimples are rivets and dimples. Any help would be appreciated. Thanks!

[dan]

If you have any concerns, now is the time to contact your EAA Technical Counselor. If you haven't made contact with one yet, it's in your best interest to do it. Just get a pair of experienced eyes on your work to confirm that you're probably doing absolutely fine.

)_( Dan
RV-7 N714D
http://www.rvproject.com

[RV_7A]

Gary,

That is simply because you didn't dimple the skin hard enough.

Here is where it wsa dimpled with a normal amount of force and then riveted.



and here is where the skin was dimpled much harder.


Notice the slight abrasion around the smoother rivet where it was clearly dimpled harder. That is what I used moving forward to ensure they all came out super flush.

http://jeffsrv-7a.com/EMPENNAGE/03-12-29.htm

Jeff

[ClayR_9A]

Those photos do a great job illustrating the difference between a 'crisp' dimple and one that isn't so great.

You can hit the dimpler as hard as you want, but if the table has some 'spring' or 'give' in it, you won't ever get a good dimple.

[RV_7A]

Very true. I hit my C-Frame pretty darn hard with my 2lb. dead blow rubber hammer. Dimpling lots of holes and hitting that hard requires hearing protection... Have no mercy on that little C-Frame. Just look for the halo around the hole will tell the story.

Jeff

[alpinelakespilot2000]

Gary--

I know this isn't the kind of advice you want to hear, but there's a great tool that will solve this problem. Trade your hammer dimpler for a DRDT-2 from Paul Merems. http://experimentalaero.com/DRDT-2.htm

Yeah, I know it's expensive (about $325), but it was my one luxury (no, I don't have a pneu. squeezer like you already do ) and I never bought the C-Frame from Cleaveland in the first place, so it really on only cost an extra $150-175. More importantly, it makes perfect dimples EVERY time and does so QUIETLY--plus it's faster since you don't have to keep picking up and putting down your hammer to adjust the skin to the next hole.

That said, I'm sure you'll get the hang of the hammer method like the rest above have suggested pretty soon and you can probably produce equally good dimples with the C-frame given proper technique.

By the way, your video got in the mail on Friday. Please let me know if there is any damage and I'll send your check back to you.

Steve

[PJSeipel]

Originally Posted by alpinelakespilot2000

(no, I don't have a pneu. squeezer like you already do )

I don't have a DRDT (yet), but I did buy a pneumatic squeezer after I finished my tailcone. You'll appreciate it after you get it. I planned to do my entire RV-10 with the hand squeezer until my tech counselor lent me his pneumatic. You'll go so much faster. It is definitely worth it.

PJ
RV-10 #40032

[LettersFromFlyoverCountry]

Dimpling isn't a science. And if you WANT to spend more money on a different sort of dimpler, by all means do so. But really you can get beautiful flush rivets by

(a) put skin between dimple dies (either squeezer or in another tool)
(b) Hit it hard enough to get the littler halo completely around it.
(c) Repeat about 12,000 times.

Want to check the quality of your dimple. Stick a flush head rivet in there and feel it with the fingers. If it feels flush, move on.

There's lots of things to spend time and more money on on this project. Dimpling ain't one of 'em.