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-   -   Did I just ruin this? (https://vansairforce.net/community/showthread.php?t=121108)

ShortSnorter 12-30-2014 12:29 PM

Did I just ruin this?
 
Yet another did I ruin this:

About 3/4 of the way through dimpling the flanges of the 915 stiffeners for the rudder I noticed that the female die was making an ever so slight impression in the crease of the bend on the stiffener. The pictures of the internal surface of the flange exaggerate (due to light reflection) the "impression" made by the side of the female die. On the reverse side you can see and feel (albeit ever so slight) the protrusion. I do have reduced diameter dies but did not think to use them or check the clearance before I started whacking away on the C-Frame. What is the consensus?




BillL 12-30-2014 12:35 PM

I think structurally, no. The stress region of the stiffener is on the edge at the beginning of your arrows. Stiffeners are cheap, so you could replace them with the next order pretty easy, if it bothers you.

It happens. :eek:

Oh - remember that one of the high probability occurrences in back riveting the stiffeners is to rivet OFF the backing plate, just a reminder.

Mel 12-30-2014 12:37 PM

Build--on!

ShortSnorter 12-30-2014 01:08 PM

Quote:

Originally Posted by BillL (Post 945784)
I think structurally, no. The stress region of the stiffener is on the edge at the beginning of your arrows. Stiffeners are cheap, so you could replace them with the next order pretty easy, if it bothers you.

Thanks Bill!

It happens. :eek:

Oh - remember that one of the high probability occurrences in back riveting the stiffeners is to rivet OFF the backing plate, just a reminder.

Hahah I've been down that road already. Hopefully I got all of that out on the practice projects.

Quote:

Originally Posted by Mel (Post 945785)
Build--on!

Thanks Mel!

plehrke 12-30-2014 01:21 PM

If it was in the skin I would redo since small dents are highly amplified visually when painted. In stiffener I would just move on.

dlloyd3 12-30-2014 02:01 PM

I ground part of the die face outside of the dimple area away so this would be less likely to happen.

Ron B. 12-30-2014 02:11 PM

You should use a small diameter female die for this application. Many places you will need one during the build. Get a #40 and a # 30.

wirejock 12-30-2014 03:00 PM

Dies
 
All my female dies have a flat side for that reason. When dimpling with the squeezer I always tape the flat side to the head of the yoke so it can't rotate.

David Paule 12-30-2014 03:16 PM

If there's a protrusion on the skin side of the stiffener and it's not very high, it'll be within the coat of Pro-Seal that some of us paint on the stiffener before riveting. If you're not doing that - if you're planning on riveting it bare, then any protrusion could affect the contour or flatness of the skin.

(The Pro-Seal is to hopefully avoid any skin cracking, although I think that's more prevalent with the .016 skins on the older airplanes like my RV-3B. It might not be worth doing on yours. And even on the older aircraft, it's only done, usually, for surfaces in the slipstream. I think.)

The only other thing to check for is whether there's any zero-radius bending, which aluminum doesn't like. Those are crack-initiation points, although as BillL pointed out, this isn't the most highly-stressed area of the stiffener.

If it were mine, and if either of these were the case, I'd replace them. Heck, I've replaced so many parts that a stiffener more or less wouldn't be noticed.

Dave
RV-3B, now building the second pair of fuel tanks, sigh....

rvbuilder2002 12-30-2014 04:25 PM

Quote:

Originally Posted by Ron B. (Post 945803)
You should use a small diameter female die for this application. Many places you will need one during the build. Get a #40 and a # 30.

Correct
There are numerous instances that the manual will specify to use a reduced diam. female die. It is listed in the recommended tools list.


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