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12-30-2014, 12:29 PM
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Join Date: Dec 2013
Location: NOLA
Posts: 229
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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?

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12-30-2014, 12:35 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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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.
Oh - remember that one of the high probability occurrences in back riveting the stiffeners is to rivet OFF the backing plate, just a reminder.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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12-30-2014, 12:37 PM
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Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
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Build--on!
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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12-30-2014, 01:08 PM
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Join Date: Dec 2013
Location: NOLA
Posts: 229
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Quote:
Originally Posted by BillL
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.
Oh - remember that one of the high probability occurrences in back riveting the stiffeners is to rivet OFF the backing plate, just a reminder.
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Hahah I've been down that road already. Hopefully I got all of that out on the practice projects.
Quote:
Originally Posted by Mel
Build--on!
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Thanks Mel!
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12-30-2014, 01:21 PM
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Join Date: Sep 2006
Location: Defiance, MO
Posts: 1,674
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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.
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Philip
RV-6A - 14+ years, 950+ hours
Based at 1H0 (Creve Coeur)
Paid dues yearly since 2007
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12-30-2014, 02:01 PM
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Join Date: Jun 2005
Location: Locust, NC
Posts: 440
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I ground part of the die face outside of the dimple area away so this would be less likely to happen.
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Dave
M20C
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12-30-2014, 02:11 PM
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Join Date: Nov 2007
Location: Yarmouth, Nova Scotia
Posts: 2,408
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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.
__________________
Thanks Ron
RV-10 SOLD
RV-14 Flying
AirCam flying
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12-30-2014, 03:00 PM
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Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,947
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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.
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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12-30-2014, 03:16 PM
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Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,435
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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....
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12-30-2014, 04:25 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by Ron B.
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.
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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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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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