Back To dimples again!!!

[60av8tor]

Originally Posted by vluvelin

Could you please post high res picture of your dimple Cleveland 426-3 and C-farme?

I'm not at home right now, but found a few from the very beginning of my build in my log. The first two are the rudder (back riveted); the third is the vertical (gun). The pics aren't the best, but the dimple/rivet/skin is almost perfectly in plane. Again, this is from a few forceful wacks and Cleaveland dies.

[rv7charlie]

There is expensive vs. cheap, and there is [whichever] good vs. defective.

There is structurally fine, and there is 'looks perfect' (in addition to structurally fine). No question to me that what's shown in the pics is safe.

Perhaps the photos over-emphasize potential issues. I took a zoomed pic of one of mine (most say my riveting is quite good) and the pic over-emphasizes the edge of the dimple next to the rivet head. Have you laid a straightedge across the driven rivet heads? For 'looks perfect': On a flat skin surface, with the straightedge along the rivet heads and 'back lit', you should see minimal light between skin & straightedge, and have a hard time picking out where the rivets are located. It should be somewhat difficult (not impossible, but difficult) to catch a fingernail on the rivet head.

There's a milspec for minimum/maximum hole size for each rivet size, & IIRC, using a #40 drill, light debur with a 3 flute debur tool and dimpling will take the hole out to the max in the spec, and if you're even slightly aggressive with the debur operation, it will go over the max diameter. It wouldn't surprise me if half the -3 rivets flying in RV's were driven in holes that are bigger than the milspec max.

FWIW,

Charlie

[vluvelin]

[quote=rv7charlie;you should see minimal light between skin & straightedge, and have a hard time picking out where the rivets are located. It should be somewhat difficult (not impossible, but difficult) to catch a fingernail on the rivet head.
[/QUOTE]
i clearly understand what you are saying
this is exactly what I trying to do

I want to understand why those dimples that cost 40$ not made to dimple like modified one ???
is this because i have no education and missing something
or
because they didn't spend enough time to make it this way
or
because each skin thickness require different dies to be made and they try to 1 fit all approach???

[rv7charlie]

In the rest of the message, I (and others) was trying to say that you may just have a defective die. Even Lear Jets have warranty claims. I've got an A/N nut that the manufacturer failed to thread. Stuff happens.

Have you borrowed someone's known-good set of dies, and tested them on some scrap to compare?

Charlie

[vluvelin]

Originally Posted by rv7charlie

In the rest of the message, I (and others) was trying to say that you may just have a defective die. Even Lear Jets have warranty claims. I've got an A/N nut that the manufacturer failed to thread. Stuff happens.

Have you borrowed someone's known-good set of dies, and tested them on some scrap to compare?

Charlie

this is ruled out
first set of dies purchased 2 years ago second set purchased last year in October used them to replace skin on wing purchased for experiment 4 more sets from same store ( with good reputation here advised by many)

there is very little variation in dimensions only 1 set had 4.8mm at the top of the head of mail die others 4.7mm

6 sets in 2 years span can not possible be bad

[vluvelin]

Originally Posted by 60av8tor

I'm not at home right now, but found a few from the very beginning of my build in my log. The first two are the rudder (back riveted); the third is the vertical (gun). The pics aren't the best, but the dimple/rivet/skin is almost perfectly in plane. Again, this is from a few forceful wacks and Cleaveland dies.

Yes looks nice!
if you can snap high resolution one from dimple both sides of skin

[sblack]

Just wait till he starts testing different primers!

[vluvelin]

http://www.aircraft-tool.com/shop/de...UCT_ID=AEDDS-3
Is this real Avery or it is not same as the old ones people refere to?

[Maddawg99]

https://www.youtube.com/watch?v=B4PvfylZcC0

[Captain Avgas]

Originally Posted by 60av8tor

I'm a broken record on my allegiance to the c-frame - used it on every dimple that I could fit. I also own a DRDT that was only used during my practice kits. I was never satisfied with the results.

+1 for this. The DRDT uses static pressure to make an impression. As a result the DRDT does not produce enough pressure to produce a really crisp dimple profile, especially in .032 aluminium. The C frame uses dynamic pressure and therefore produces a much more defined profile.

I used a C frame and 2 solid whacks with a heavy computhane hammer....perfect dimples with well seated rivets. You can actually feel when the dimple is fully formed....you can feel it "bottoming out".

I used the C frame for all external skins where I obviously wanted deep seated flush "cosmetic" rivets. For internal dimples (ribs, bulkheads etc) I used a pneumatic squeezer wherever I could gain access.

I tried a friend's DRDT for comparison and it just does not produce the same quality. This is not defence of choice...it's just a fact.

I suspect that some people who use a DRDT for dimpling are satisfied with it because they don't know any better. Or maybe it just comes down to how fussy one is.