Plug for Bob: If you are ever needing aircraft tools, I would recommend strongly that you consider Avery Tools. Nice people, customer-focused and willing to help a member of the RV family out in a pinch..... So....
Have you ever wanted to not use an oops rivet to fix a bad -3 dimple? Here's a tool that Bob Avery made for me that takes a -3 to a -4 so that you can use an AN426AD4 as called out in AC43 to fix a bad hole where an AN426AD3 was supposed to go...
In my case I had some problems with off-center upset heads on the top wing skin-to-rib substructure joint. The rivet was drilled out, and putting a -3 rivet back in was problematic without clenching the rivet.... enter the tool that Bob was gracious enough to construct for me....
What you see here is a 1/8" spring-back dimple die with the pilot machined out to accept a longer pilot... As pictured the two-piece male dimple die has a special removeable pilot to allow it to seat properly in the female die and to guide the female die directly over the back-side of the skin / rib structure to be dimpled.
The male die is attached to a "C" tool sold by Avery, and the dimple is formed with the help of a 4X rivet gun, and a partner holding backup with the bucking bar / female dimple die on the other side......
Here's a picture of the finished product - a nice dimple ready for an AN426AD4 rivet...
Here's a picture of the female die.... I had a friend (Bud Warren - God rest his soul) turn down the head of the bucking bar to help reduce the distance between the axis of applied force and the center of mass of the bucking bar. He also drilled a hole in the end of the bucking bar to allow the insertion of the female die...
I did need to do a little cleanup on the dimples..... starting with a light reaming in the hole to clean it out (since the female die has a sharp transition from the die surface to the hole for the pilot, it does promote some scuffing of the pilot, which can scuff the inside of the rivet hole...... but this can be removed by lightly reaming out the dimpled hole...). Also, since there is not a continuous surface between the male die and the pilot, it leaves an almost imperceptible half-circle indentation inside the dimple.... this is taken out with a rolled up piece of 320 grit sandpaper in the hole. The next step is to vacuum out any grit in the hole, then the last touch-up step is to clean the back-side of the hole with acetone to get rid of any smudges caused by the female die impinging on my interior-side epoxy primer... and voila... a dimple ready for an AN426AD4 as called out in AC43!
Have you ever wanted to not use an oops rivet to fix a bad -3 dimple? Here's a tool that Bob Avery made for me that takes a -3 to a -4 so that you can use an AN426AD4 as called out in AC43 to fix a bad hole where an AN426AD3 was supposed to go...
In my case I had some problems with off-center upset heads on the top wing skin-to-rib substructure joint. The rivet was drilled out, and putting a -3 rivet back in was problematic without clenching the rivet.... enter the tool that Bob was gracious enough to construct for me....
What you see here is a 1/8" spring-back dimple die with the pilot machined out to accept a longer pilot... As pictured the two-piece male dimple die has a special removeable pilot to allow it to seat properly in the female die and to guide the female die directly over the back-side of the skin / rib structure to be dimpled.
The male die is attached to a "C" tool sold by Avery, and the dimple is formed with the help of a 4X rivet gun, and a partner holding backup with the bucking bar / female dimple die on the other side......
Here's a picture of the finished product - a nice dimple ready for an AN426AD4 rivet...
Here's a picture of the female die.... I had a friend (Bud Warren - God rest his soul) turn down the head of the bucking bar to help reduce the distance between the axis of applied force and the center of mass of the bucking bar. He also drilled a hole in the end of the bucking bar to allow the insertion of the female die...
I did need to do a little cleanup on the dimples..... starting with a light reaming in the hole to clean it out (since the female die has a sharp transition from the die surface to the hole for the pilot, it does promote some scuffing of the pilot, which can scuff the inside of the rivet hole...... but this can be removed by lightly reaming out the dimpled hole...). Also, since there is not a continuous surface between the male die and the pilot, it leaves an almost imperceptible half-circle indentation inside the dimple.... this is taken out with a rolled up piece of 320 grit sandpaper in the hole. The next step is to vacuum out any grit in the hole, then the last touch-up step is to clean the back-side of the hole with acetone to get rid of any smudges caused by the female die impinging on my interior-side epoxy primer... and voila... a dimple ready for an AN426AD4 as called out in AC43!
