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DRDT vs C-Frame

Barneybc12d

Well Known Member
Is there a benefit to buying both a drdt-2 and a c-frame besides helping the economy? Going to build a RV-14A.
 
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I have the DRDT and think it works very well. I only tried a few dimples on a C frame - and it worked well too. Im not sure what the advantage of having both would be. Maybe a bad shoulder it would be easier to hammer than pull the lever? I think the real cool thing would be to have the air powered DRDT with a foot switch. That would leave both hands available to keep the sheet level and in the right place.
 
DRDT-2

I used a DRDT-2 and wouldn't build without it. It makes an excellent dimple when using quality dies. I did need a C frame for some dimpling on the -8 that the DRDT-2 would not accomplish. On rare occasions the arm on the DRDT-2 prevents the use of this tool. An example would be a large sheet that already has formers or stiffeners riveted to the sheet.

My preference would be a DRDT-2 and an Avery C frame with all the accessories.
 
Does the c-frame get used to back rivet?

I have both and use both. I especially like using the C-frame to back rivet, using Cleaveland's 12" back-rivet set, made just for that purpose. See the video at the link.

Update: well I remembered the Cleaveland site once hosted the C-frame back riveting video, but now it's just a generic back rivet demo. See this EAA video by Wally Anderson instead.

--
Stephen
 
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+1 DRDT2

I have used both the DRDT2 and the traditional C-frame. While the C-frame is adequate for dimpling (and back-riveting), the DRDT2 is worth the investment. It makes great dimples, it's quiet and it's almost impossible to accidentally figure 8 (i.e. make an extra hole). I can't imagine using a c-frame to back rivet for anything but small parts, which can easily be riveted using a squeezer. Any situation where you have large parts, getting riveted together will usually involve a rivet gun and bucking bar, so I don't think the C-frame would get used much for back-riveting. My $0.02.
 
I used a C-Frame for all of my dimpling and it worked just fine. Yes, it makes some noise as you pound on it with a big old nylon hammer, but the dimples come out nice and crisp. Save your money unless you have to be quiet. Hammering can be therapeutic! :D
 
I built my airplane using the C-frame. If I was doing it again, I'd have the DRDT. It is a quieter, faster process, and there are a LOT of holes to dimple.
 
No DRDT

As far as I'm concerned the DRDT would make a good boat anchor and nothing more :eek:.

The only reason I have one is to show customers why they are worthless. I can pick out a DRDT built airplane over a C-Frame build any day of the week :rolleyes:

I dimple LOTS of holes and ALWAYS go my C-Frame and hammer :D.

This seems to be one of those "I have one so it's great" tools. I have both and call 'em like I see 'em.....save your money and make some of the best dimples in town......no charge for this advise :D:D!
 
Why?

Rick, what is it about the c-frame dimples that you prefer over those formed with a DRDT? I am planning to start building an RV-12 in the not too distant future so it does not affect me in the near term, but I am hoping that there will other builds in the future so I am curious.

Tom
 
Rick makes some pretty strong statements there, but doesn't say why. Perhaps I can shed a little light based on my experience. I, too, have used both tools.

I started on my empennage with a DRDT-2 and soon had my first visit from my EAA technical counselor. I knew he didn't have one of these tools. They were new at the time, and I was looking forward to seeing him "ooo" and "ahh" over this newfangled tool. Turns out, he didn't like it at all. I was shocked and disappointed, because I thought it was so cool. Turns out, I had the settings wrong and I was under-dimpling. He told me he had seen several DRDT's being used by newbies like me and every one of them produced under-dimpled dimples. This leaves large distorted or depressed areas, or "moon craters" around each rivet. Get the light reflecting off the surface of the skin and it really shows!

000_0905%20(Small).jpg


Later, I visited him at his shop and he demonstrated his C-frame for me. He whacked each dimple twice with his hammer. He hit it hard, especially the second blow. It was like "whack, WHACK!", move to a new hole "whack, WHACK!" The first blow forms the dimple, and the second one really makes it crisp and sharp. He told me "don't be shy. You've gotta beat that aluminum into submission". I'll tell you, I was impressed. The skin around his dimples was dead flat and the light reflecting off the skins showed no distortion whatsoever. His finished rivets looked fabulous.

Since I didn't have a C-frame at home and I knew what my problem was, I set about to see if I could improve the dimples from the DRDT. I learned that if I adjusted the ram down some more, and locked it in place in a more extended position, it would work much better. I set it so the dies contact each other well before the arm is pulled all the way down. About 2/3 of the way down (this is before any metal part is in place for dimpling). It ends up taking much more force to pull the arm all the way down. You can actually see the big steel arms on the DRDT flex and bend apart a little bit under the force. And I pull down on each dimple twice with it, just like he did on the C-frame. The second pull, I even try to ram it down, or "whack it". From this point on, my dimples looked really good. You'd be hard pressed to see any difference.

Later on, I found an almost brand new C-frame for sale on eBay for half the price of a new one, and I couldn't resist. I bought it. So after using both, I can honestly say that if you adjust the DRDT like I described above and hit each dimple twice with it, you'll have very nice dimples and good-looking rivets. You'll have results you won't be ashamed of, and it's very hard to tell the difference. However, for the most discriminating builder, the C-frame does have a very slight edge, IMHO. You just can't beat those nice crisp hard-whacked dimples. That's my experience and my humble opinion. So what did I do?

I ended up using my DRDT to dimple all the ribs, stiffeners, flanges, underlying parts and structures, and so on, wherever I could use it. The bottom skins on my wings, and the belly skins on the fuselage. I still love the tool! But I used the C-frame for those dimples that are the most highly visible, such as the top skins on my wings, the fuel tanks, and the fuselage skins. Even though it was more work. Here's what my completed wings look like. No craters.

100_5067%20(Small).JPG


I hope this helps. The DRDT is an excellent tool and can produce excellent results! Like any tool, it has to be adjusted and used correctly to get the best results.
 
I hope this helps. The DRDT is an excellent tool and can produce excellent results! Like any tool, it has to be adjusted and used correctly to get the best results.

Truly excellent analysis, Bruce. As I've said before, I own and use both tools. I completely concur with your suggestions (which isn't so surprising since I saw your advice before I started building either here or on your site, and I followed it in setting up my tools).

I'm certain Rick's opinion is 100% right for anyone wanting to build a quality, award-winning airplane like he's done so many times. I don't harbor the delusion my first build is anywhere near that level. I'm building a tractor. So for me, other factors (like being able to work late at night without bothering my family and neighbors) must take precedence.

--
Stephen
 
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ExperimentalAero Response

As the designer and manufacturer of the DRDT-2 I have been very silent when it comes to promoting the tool through the posts on this forum. I believe the tool sells itself on its own merits. It turns out that my best salesmen are the builders who use the tool. I am humbled by the flattering comments many have posted on the forum. Who better to provide the RV community with real experience with the tool then the thousands users.

However in this thread there is a post that blatantly calls the tool ?worthless? and ?a boat anchor?. This individual has a tremendous amount of experience building RV with over 25 completions to his credit and I am sure is well respected in the RV community. However with the vast experience and respect in the RV community comes a level of responsibility. I believe this individual is doing an injustice to the tool and the RV community with his comments.

The DRDT-2 was conceived out of necessity. Back in the early days (1984) the c-frame dimpler wasn?t commercially available or just didn?t exist. So early RV-3/RV-4 builders had to make due with what was available. You can build an RV with a rivet gun, hand squeezer, bucking bar and pop rivet tool. That is how I built my RV-4. I even built my spars from parts as I had no choice, so it can be done. The RV even sold for a premium over most of the RV-4 built and the plane is still flying today. The point is you can build with minimal tools, however it was not easy and dimpling skins with a pop rivet tool was a laborious task. At the end of my RV-4 build I conceived the DRDT. It was too late to help on my project but I knew if I were to build in the future I would build the tool.

Fast forward several years and I built the tool to build my RV-7A. When other builders learned about the tool I received numerous requests to manufacture it. It was at that time I started ExperimentAero to provide a quality tool to the builders.

The comment that the DRDT-2 doesn?t dimple well is just false. The finished look of the skin around a set rivet is affected by several factors. The dimpling tool, dimple dies, rivet gun, rivet gun air pressure/flow, mushroom set diameter, mushroom set face curvature, bucking bar, rivet size variation, and the skill of the shooter and bucker all influence the final appearance. Even the viscosity and capillary action of the primer and paint has an effect on the final appearance. Any improperly set up or improperly used tool will produce results that will vary tremendously. As I mentioned there are differences in dimple dies, not all are the same exact profile. Prior to ever selling a unit several of the leading tool suppliers tested the tool with their own dimple dies and were very satisfied with the results.

It is not uncommon to be asked if the DRDT-2 dimples ?as well? as the impact c-frame dimpler. You need to decide what ?as well? means. Does the DRDT-2 produce the same consistent ?crisp? dimple every time regardless of the user dimpling? Yes. Can you hear the DRDT-2 when you dimple? No. But you surely can hear the c-frame dimpler in the house down or the block when you use it.

In summary the DRDT-2 isn?t worthless to almost all the builders (I appears there is one who posted who thinks it is). Any tool that makes building an RV easier with consistent results is of benefit to the RV community.

If a builder wants a tool that makes dimpling consistent, easy, safe, less fatiguing and noise free the DRDT-2 is the tool of choice.

For those interested in finding more of what other users think about the tool search on the Forum with the keyword ?DRDT-2?.

Here is a link to some of the DRDT-2 testimonials. http://www.experimentalaero.com/drdt-2 testimonials.htm

Here is a link to my FAQ page. http://www.experimentalaero.com/frequently_asked_questions.htm
 
Neither.

Buy the Numatx 3060. You can attach the hydraulic squeezer to a C-frame (you have to build this) for dimpling. Then you can pull it off and use it as a hand squeezer.





Cheers
ken
 
Similar

I wanted a combo of all of it. I essentially built a "C" frame of similar dimensions to the DRDT-2, but out of 3/8" tube, added 1/4" doublers to the back for low deflection (I get about 0.0015" deflection max as measured at the ram), attached a separate actuator ram to the front so I could change between the "C" frame and squeezer very quickly.

2d75zxj.jpg



Here I am using the hand squeezer to dimple the ribs with the "C" frame and actuator in the background.
 
DRDT-2 Dimples

I used a DRDT-2 and a Pneumatic squeezer for my build. In my experience, the quality of the dimples has a lot to do with the tool setup. See my post from a few years ago http://www.vansairforce.com/community/showpost.php?p=286707&postcount=3. On the DRDT-2, it is critical to set some "preload" to get good crisp dimples. I would suspect that the proper preload is some function of material thickness, but the one turn I ended up using yielded perfect dimples every time. (and yes - I have had plenty of opportunity to look at dimples/finished product that was done with the C-frame). Nothing wrong with the C-frame, but there's nothing wrong with the DRDT-2 either.

Just my opinion
 
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