[jchang10]

Sigh, another booboo. I was dimpling with the pneumatic squeezer, while talking on the phone, and this is the result. It's ironic, since I was talking to another pilot, explaining what i was doing, and how mindless some of the building actually is. JINX'ed! 2 minutes later...

This is on the horizontal stabilizer skin, fortunately, on the bottom, inboard edge, so this should get covered up by the fairing.

However, the hole itself is only 2D from the closest other hole and only 1.5D from the edge of the skin. The minimums should be 3D to another rivet hole and 2D edge distance.

Cosmetically, this is a non-issue. However, because of those minimums, I would think the biggest risk is cracking starting here.

Finally, just putting in a rivet will interfere with the inboard rib flange, unless i can shave it flush to the skin, i guess.

I hope someone can advise me on the best fix? It seems like a relatively minor booboo, so I am hoping for a simple fix? I hope!

Thank you for any advice,
Jae

 

[mlw450802]

...
However, the hole itself is only 2D from the closest other hole and only 1.5D from the edge of the skin. The minimums should be 3D to another rivet hole and 2D edge distance.

Cosmetically, this is a non-issue. However, because of those minimums, I would think the biggest risk is cracking starting here.

Finally, just putting in a rivet will interfere with the inboard rib flange, unless i can shave it flush to the skin, i guess.

I hope someone can advise me on the best fix? It seems like a relatively minor booboo, so I am hoping for a simple fix? I hope!

Thank you for any advice,
Jae

Firstly, the edge distance requirements assume that there will be a stressed rivet in the hole. No rivet, no stress, no edge distance requirement.

Secondly, a reasonable fix might be to just mash the dimple flat by squeezing between two flush sets then drill a smooth hole and deburr it.

Since it's on the bottom, just leave it open so there will be no interferences and march forth, knowing that Grand Champion is no longer a goal.

Really, it's not a big deal and few of us has made it through our first plane without a similar screw-up.

-Mike

 

[TJoyner]

I did the same thing on an HS skin. Van's told me it was a
"rite of passage," and not to be suprised if it happens again..
I just squeezed a rivet in there and kept on going.



TWJ

 

[avaviat]

This is by far the most common type of "I just screwed up" post I've seen... I'm convinced we all do it. I know I've done it -- twice, so far.

 

[Tom Maxwell]

Not Yet But...

I haven't done this yet but I just finished the emp and am waiting on the wings so I have a lot of opportunities left to do so. It seems that this almost always occurs while using the pneumatic squeezer or while pounding the C-Frame.

I am using the DRDT-2 which has such positive and smooth control that I wouldn't think it possible to do this without getting really careless or completly zoning out during a dimpling session. I do understand how a slip could easily occur while using a C-Frame and mallet.

I also understand how it can occur with the pneumatic squeezer. There is a lot of force behind that little sucker and it is pretty much all or nothing. It's mass also makes it somewhat of a challenge to hold steadily. It is very easy to fire that puppy prior to wanting to do so or to have it slip a little in the process. The trigger safety on mine creates some stability issues as I have to push it forward and then down to get it to operate. As steady as I try to be, I almost always move the squeezer a little bit while pushing the trigger past the safety stop. I am getting good at recentering the sets on the rivets as the squeezer eases closed. I can see why it is very easy to punch an extra hole while dimpling.

So I guess my question is, why are so many people use the pneumatic sqeezer for dimpling? It really isn't that difficult to dimple with either a hand squeezer or a DRDT-2 or even the C-Frame, and the additional control that these offer over the pneumatic squeezer should all but eliminate these issues.

Maybe I am clueless but it seems to me that using the pneumatic squeezer in this capacity is just asking for problems. It is kind of like using a sledge hammer on a center punch. Yeah you can do it if you are really careful, but with a slight lapse in concentration you have a new hole.

 

[avaviat]

So I guess my question is, why are so many people use the pneumatic sqeezer for dimpling? It really isn't that difficult to dimple with either a hand squeezer or a DRDT-2 or even the C-Frame, and the additional control that these offer over the pneumatic squeezer should all but eliminate these issues.

Can't answer for everyone, but, for myself...
1) I don't have a hand squeezer.
2) I don't have a DRDT-2
3) One of my "extras" was with the C-Frame (skin went up and slid as hammer went down), so that is no solution.

As you say, the control on the pneumatic squeezer lends itself to accidental discharge. The whole thing is a little too heavy and your gripping hand also controls the trigger. After my little accident I hooked up a $20 foot pedal to the pneumatic squeezer and haven't had a problem since.

 

[jchang10]

Thanks

Thanks for the advice. Just drilling it and leaving it makes good sense to me. If i can fit the rivet in without interfering with the rib, i'll give it a try.

As far as using the pneumatic squeezer for dimpling, i may have to reconsider using it in the future. Using the c-frame solo is a chore, so i prefer doing any dimples by hand if i can reach them.

anyway, thanks again for guiding me through this "rite of passage!"

jae

 

[Jamie]

As you say, the control on the pneumatic squeezer lends itself to accidental discharge. The whole thing is a little too heavy and your gripping hand also controls the trigger. After my little accident I hooked up a $20 foot pedal to the pneumatic squeezer and haven't had a problem since.

One thing that worked really well for me on the smaller skins is to put the pneumatic squeezer upside down in the bench vice (the vice will hold on to the yoke). I had my doubts when it was suggested to me but it really is a nice way to do it.

The old unintentional hole in the skin trick is no big deal as I do believe almost everyone has done that at least once. Keep on pounding and I'll get back to the lovely smell of melting plexiglass.

 

[johnp]

extra dimple hole -- rite of passage

The old unintentional hole in the skin trick is no big deal as I do believe almost everyone has done that at least once. Keep on pounding and I'll get back to the lovely smell of melting plexiglass.

i was actually well into my wings, and feeling pretty smug every time i saw a post like this, because i got all the way through my empennage without doing it. you can guess the rest.

 

[jchang10]

Did it again! Figure 8 this time

Damn, I did it again. Can anyone recommend a good way for dealing with figure 8 dimple errors. This error is in the bottom flange of the rear spar for one of the elevators. I already broke my cogsdill tool trying to clean up the hole - not a recommended technique.

This thread is turning out to be an encyclopedia on fixing dimpling mistakes!

Jae

 

[avaviat]

Get a big ruler (not one of those effete "scales" but a good old wooden ruler) and whack yourself with it every time you stop paying attention while using the squeezer. OK, OK, it was just a thought... geeze....

I used a pin punch to flatten and reshape the metal as much as I could. I was hoping I could redrill to go up a size, but it would've been too big a rivet for spacing. I made a new hole further down the part instead.

I'm not much of one to talk (I got "enthusiastic" and alodined my h. stab spars before I dimpled them) but AFAIK it is better to finish all the dimpling etc before priming? Maybe I'm wrong about that.