Dimple Dies

Jarrett · #1 06-24-2020, 10:19 PM

Hello all! Just finished my vertical stabilizer last week and I am now moving forward with both the rudder and horizontal stabilizer. Today I was looking over my vertical stabilizer and I noticed that there was a very small gap between the manufactured heads and the dimpled portion of the skin denoted by the slight shadow under the heads.
https://photos.app.goo.gl/kJoRtW5ZXgd4W93r6
https://photos.app.goo.gl/SY3f6gkt1NVSyvE57
My first thought was that the manufactured head was not perfectly flush with the skin (maybe a riveting mistake), so I put the flat end of a ruler over top of the rivets and saw that the rivets were indeed flush. I then took a look at my practice project and realized that these rivets did not have this same shadow under the rivets. This is when I realized that on the practice project I used Brown dimple dies and on my V-Stab I used Cleaveland dies. I then went ahead and did a controlled test. I took a piece of scrap and dimpled two #40 holes using both dies.
https://photos.app.goo.gl/o1TpuWdVoYzg93pz7
Notice how with the die on the left there is the slight gap, and on the right there is none, which is what I had suspected. I have had a great experience with both companies, so I'm not trying to start any wars

Is this gap normal for those that have used the Cleaveland Dies? Once the plane is painted these gaps won't be visible so it's not the end of the world, but as I am ready to dimple the rudder skins I want to know if I should change back to the other dies, or be worried at all? Thanks!

GeoffP · #2 06-24-2020, 11:00 PM

I started my build with dimple dies from Brown, so most of my HS & VS were done with those. I bought some Cleaveland dies also, and I can't honestly say that I've noticed much of a difference through the rest of my build to date.

Generally I prefer the Cleaveland dies, but at the end of the day if the parts nest & the rivet goes in OK I don't get too worried. If the rivet heads aren't totally flush for me I usually put it down to my riveting technique (perhaps not quite enough pressure on the gun) rather than the dimple. I assume that you had whatever tool you used to dimple set properly, or if you used a C-frame that you gave it a solid whack.

Did you perhaps use a sub-structure die on the skin? That might explain the slight gap.

Jarrett · #3 06-24-2020, 11:51 PM

Hey Geoff, for the skin I just used the standard 3/32 dimple dies. I've been doing a little bit of digging around and I've found that some builders have similar results.
http://wolfcry.net/rv-14/blog#gallery-14
Initially I thought it was my riveting technique, but even before riveting when the rivet is placed in the hole there is a tiny gap. All of the parts fit together nicely and the rivets are flush, so I think I'll just have to live with it (won't notice it after paint). I'm using a DRDT-2 for my riveting (which I love), and have been very careful not to under-dimple. Thanks!

Jarrett · #4 06-25-2020, 01:14 AM

I found two threads on this issue:
http://www.vansairforce.com/communit...?t-157214.html
http://www.vansairforce.com/communit...d.php?t=152064
Looks like other builders have had similar issues with these dies...

wilddog · #5 06-25-2020, 04:02 AM

Something is not right. Not sure what. Almost looks like -4 dies and -3 rivets? Wish you were closer so I could be more help.

Tom Martin · #6 06-25-2020, 05:02 AM

For you, with your method, the Brown dies look much better. I would recommend using them. As your project gets further along try the test again. It would be interesting to see if the results are the same.
Nice work, you have a good eye for detail!

MS19087 · #7 06-25-2020, 05:45 AM

Cleaveland sells a substrate did which I use all of the time. It is to be used to dimple substrate structures like ribs or nested skin overlaps. Looks like you could be using that by mistake. It will leave a slightly larger dimple to allow cleaner nesting. Just a thought. There is a part number etched on the die. Check it out.

wirejock · #8 06-25-2020, 08:51 AM

Check the side of the dies for size. Should be engraved 426-3
It's possible you have Cleveland Tank or Substructure dies. They wll be stamped "426-3T" or "426-3SS". Could also be dies mixed up.

Jarrett · #9 06-25-2020, 12:43 PM

Hello everyone, thanks for the input! For the skins I used the standard CAT 426-3 and I used the CAT 426-3s (reduced diameter) only for the ribs/spars as per instructions. I'm dimpling the rudder skins today, so I think I'm going to go ahead and use the Brown dies for now. I'll maybe do one or two holes with the Cleaveland dies to get another side-by-side comparison. Thanks!

Captain Avgas · #10 06-25-2020, 07:04 PM

Quote:

Originally Posted by Jarrett

Hello everyone, thanks for the input! For the skins I used the standard CAT 426-3 and I used the CAT 426-3s (reduced diameter) only for the ribs/spars as per instructions. I'm dimpling the rudder skins today, so I think I'm going to go ahead and use the Brown dies for now. I'll maybe do one or two holes with the Cleaveland dies to get another side-by-side comparison. Thanks!

What type of device are you using to form the dimples. When I see dimples like yours it?s usually the device that?s the problem rather than the dimple dies.