Over dimpling?

Clarkie · #1 12-29-2011, 03:26 PM

Hi Guys,

I'm just getting started and was wondering if it possible to over dimple using the DRDT-2 on the skins? My rivets are flush, but for whatever reason, I don't think it looks very clean.

fehdxl · #2 12-29-2011, 03:39 PM

Nope, can't over-dimple.

Are you sure you've got the DRDT adjusted correctly? I can't remember the exact verbiage, but the dies need to make contact, then the handles moves a some more.

Are you getting the 'witness' mark around the outer edge of the die? You should be.

-Jim

Clarkie · #3 12-29-2011, 03:41 PM

Yes.. I am getting the little circle mark around the dimple, but I expected it to look more crisp than it does.

fehdxl · #4 12-29-2011, 03:47 PM

I'd say the DRDT is adjusted correctly then.

If you're comparing it to other dimples, then at this point, it's probably a variation in the different manufacturers of the dies. They are not all created the same.

How does the rivet sit in? If it's flush, paint will cover it.

If you're polishing, then you might want to get different dies.

Maybe a picture could illustrate to the smarter than I am guys.

Best,

-Jim

Clarkie · #5 12-29-2011, 04:01 PM

http://i1108.photobucket.com/albums/...IMG_0990-1.jpg

airguy · #6 12-29-2011, 04:08 PM

That looks pretty much like my airplane...

Clarkie · #7 12-29-2011, 04:09 PM

So it looks ok to you?

DCat22 · #8 12-29-2011, 04:16 PM

I'm not very far in, but 3/4 turn past contact of the dies seems to work well for me. And the Cleveland dies seem to be regarded as excellent -- but I have nothing for comparison.

I have a c-frame too... At some point I was going to do a comparison test, and see how they looked side by side.

schristo@mac.com · #9 12-29-2011, 04:19 PM

Dimples created with a squeeze method will not be as crisp and ones from a mechanical hammer but the DRDT sure is useful and I used one as well. You can compare dimples from a rivet gun (with appropriate sets) or hammer blow to the ones you are making with the DRDT for a good reference. To improve on the flushness from the DRDT dimples make sure that you are really getting good flex in the steel frame arm when you make the dimple, also some have chosen to double strike the dimple with the DRDT and have reported good success... if the arm is adjusted correctly I found the dimples to be quite satisfactory but no matter what, you will get a crisper edge and flatter face with a mechanical blow method.

BSwayze · #10 12-29-2011, 04:32 PM

Tom,
The biggest risk from the DRDT-2 tool is UNDER dimpling. Your picture isn't real crisp, but if I'm seeing shallow depressions around each rivet, it's definitely under-dimpled. They really show up if the light is reflecting just right. I had this same problem early on with mine. My tech counselor at the time showed me his C-frame and how he used it, whacking firmly twice on each dimple, with absolutely perfect results. I heard the famous quote "you gotta beat that aluminum into submission". I realized I was being too timid when it came to dimpling.

I was later able to duplicate his nice dimples on my DRDT-2 by adjusting the ram downward and locking it in a position so that the dies make contact with each other about 2/3 of the way through the handle stroke. This is with NO aircraft parts in there; just the dies. When I'm dimpling, I pull the handle down once to form the dimple, and then I slam it down hard a second time on each one to really "coin" the dimple. The force is strong enough that you can actually see the big metal beams on the tool separate and deform slightly with each one. Try it on some scrap. You should see a big difference. I have more discussion and pictures on my web site here:

Dimpling with the DRDT-2

I also agree with a previous post about quality dimple dies. I spent the money on good spring-back dimple dies. It's worth it. Good luck as you progress!