ExperimentalAero's comments
Thank you all for posting your views on the dimpling comments in the article.
To Randy, thank you for your follow-on response.
The Internet and the forums are great tools for information. Good news travels fast, negative news travels faster. I am concerned that the information in Randy's article unintentionally painted a negative picture of the DRDT-2 performance with respect to under dimpling and final quality of the finished dimples.
I want to make sure everyone who reads this understands that the DRDT-2 produces high quality dimples when setup and used properly. The manual explains how to set up the tool, which also includes alignment and preload directions (
http://www.experimentalaero.com/DRDT-2 Manual & Drawings.pdf). I extensively tested the tools about a year before it was introduced to the homebuilders. These tests included intentional misalignment and various preload adjustments on various thicknesses of materials. Time after time I found that is was very hard to set the tool up incorrectly and setting the preload was easy.
One thing I have found that plays a more important role in the quality of the dimples are the dimple dies. Not all dimple dies produce the same results. There are at least 5 manufactures of dimple dies out there and all are cut slightly differently. Through in to the mix spring-back vs standard dimple dies and there are even more variables. One area that was unclear in the article was whether the same dimple dies were used with the DRDT-2 and the impact c-frame dimpler. I have used my set of dimple dies in both the DRDT-2 and c-frame dimplers and there is very little difference in the results. Once painted or polished the difference is imperceptible. The DRDT-2 produces the same quality dimples as a good hand or pneumatic hand squeezer (properly setup).
I do believe impact c-frame dimpling can achieve a crisper or sharper dimple. Think of the coins we use as currency. These are produced by stamping which replicates the master with fine detail. Impact dimpling should be called "stamp" dimpling because that is what it truly is. The harder you hit the better the replication. However the harder you hit the more work hardening to the dimpled area and the possibility of damage to the skin. In additional the quality/consistency of the impact dimple varies with the each hammer blow.
The DRDT-2 is in the hands of builders, training centers, aircraft repair facilities and aircraft factories all over the world. The DRDT-2 must be working well for these customers or I would hear about it (I get emails regularly from customers thanking me for a wonderful product). I have new homebuilders as well as several repeat builders (2nd or 3rd RV's). These repeat builders have a lot of experience with the impact c-frame dimpler but have chosen to switch to the DRDT-2 on their new project. The training centers have been helping new builders build literally hundreds of empennage kits with the DRDT-2 and have a tremendous amount of experience with both the DRDT-2 and the impact c-frame dimplers.
If you have any doubts just post your questions on the forum. If you want to get some real world high use feedback on the tool contact the Alexander Tech Center (RV training center
www.buildtofly.com), they have been using the tool extensively and have produced several empennage kits with the tool (don?t know the exact number but I believe it is 100+).
The DRDT-2 is for the builder who wants a better way to dimple that is consistent, easy, safe, less fatiguing and noise free then the impact c-frame dimpler. If you have any questions or comments please email me
[email protected]. Feedback is always welcome.
Build on...............................................