Over countersinking?

[jcarne]

Originally Posted by Mort04

The verdict is in, time to order new HS-710 and 714 reinforcement angles. Vans got back to me and as a couple people mentioned earlier in this thread 7 clicks past flush is what I should have done, regardless of the two peices not mating completely tight. Not sure why I would question that as a first time builder......

Anyway, one thing Vans pointed out to me that I didn?t think about is the shape of the dimple vs the countersink. It is slightly different. Below is Vans response to me. Thanks for everybody?s input.


That does look substantially deep. I would probably start over.

The concern is that if you go too deep, you won?t have a solid interface between the skin and the underlying structure. You will almost always have some gap showing between the skin and underlying structure. The edge on that countersink is pretty sharp whereas the edge on the dimple is rounded. 7 clicks beyond flush is safe.

Don't take it too hard, I had to do this area 3 times before getting everything just right! I still have them part numbers memorized...

[Mlidzct]

I was running into the same issue. I countersunk .007 deep (verified by putting a rivet in the hole and measuring depth with end of caliper. The dimple on the spar didnt seem to nest right. Since I knew I had the correct countersink I started looking at the dimple. Bottom line, the dimple from the drdt-2 does not nest while the dimple formed with the c-frame fits just right. When you look real close the dimples look almost identical but the one formed by c-frame is sharper.

[vlittle]

Originally Posted by Mlidzct

I was running into the same issue. I countersunk .007 deep (verified by putting a rivet in the hole and measuring depth with end of caliper. The dimple on the spar didnt seem to nest right. Since I knew I had the correct countersink I started looking at the dimple. Bottom line, the dimple from the drdt-2 does not nest while the dimple formed with the c-frame fits just right. When you look real close the dimples look almost identical but the one formed by c-frame is sharper.

Bingo! Many new builders underset their dimples, and the best way to dimple is a c-frame or a properly adjusted pneumatic squeezer. The dimple should be crisp and the skins should not be wavey around the dimple.

I have seen builders using 'better' tools with fancy names that do a worse job than the old-school tools. A c-frame and a dead blow hammer is noisy but effective.

V

[Mort04]

Originally Posted by vlittle

Bingo! Many new builders underset their dimples, and the best way to dimple is a c-frame or a properly adjusted pneumatic squeezer. The dimple should be crisp and the skins should not be wavey around the dimple.

I have seen builders using 'better' tools with fancy names that do a worse job than the old-school tools. A c-frame and a dead blow hammer is noisy but effective.

V

With that being said, I used a pneumatic squeezer for my dimples on the 702 spars. I still need a DRDT-2 or a C-frame. For the money, the C-frame seems more economical. Is it the consensus that the C-frame is an all around better dimpling tool?

[jcarne]

Originally Posted by Mort04

With that being said, I used a pneumatic squeezer for my dimples on the 702 spars. I still need a DRDT-2 or a C-frame. For the money, the C-frame seems more economical. Is it the consensus that the C-frame is an all around better dimpling tool?

This is debated heavily, if you do a search you will find lots of information. I use a c-frame and works great! at a third the cost mind you...

[tims88]

Personally I believe it has more to do with the dies than the tool as long as a proper amount of pre-load is used on the DRDT-2. I have both a DRDT-2 and a C-frame and with the same dies I cannot see a difference between the dimples.

As for the dies, I have a new set that came with my toolkit and an old set (probably 10 years old by now) that came with tools I am borrowing from another builder. The older set produces a dimple with much crisper edges than the new dies, but even with the old dies I cannot see a difference between the DRDT-2 and the C-frame.

[Mlidzct]

Originally Posted by tims88

Personally I believe it has more to do with the dies than the tool as long as a proper amount of pre-load is used on the DRDT-2. I have both a DRDT-2 and a C-frame and with the same dies I cannot see a difference between the dimples.

As for the dies, I have a new set that came with my toolkit and an old set (probably 10 years old by now) that came with tools I am borrowing from another builder. The older set produces a dimple with much crisper edges than the new dies, but even with the old dies I cannot see a difference between the DRDT-2 and the C-frame.

Just to clarify in my example, I used the same set of dies in my drdt-2 and the c-frame. They look about the same to the eye. The c-frame one nests a machined countersink, the drdt-2 one does not. Drdt-2 is set properly and I use it everywhere else. But when trying to fit formed dimples to sharp machined countersinks the c-frame works better for me.

[boom3]

Don't feel bad, the HS-710 was the first part I had to reorder for the exact same reason. I lost sleep for a couple nights but got over it.