Perfect #30 holes when dimpling

[blueisthenewblack]

I had an e-mail conversation with Mike from Cleaveland regarding the dimpling process with DIENQ, since the product description has a different process from the Panther build manual.

Per Mike, the correct process with the Cleaveland DIENQ is:

1) Drill with #40 Jobber drill bit & Cleco as you go along (with proper size Cleco)
2) Disassemble
3) Deburr
4) Dimple with DIENQ
5) Use #30 reamer to enlarge hole. (Feed the reamer slowly to eliminate the need to deburr again.)

Both the skin and substructure should be dimpled with this method using DIENQ. A C-Frame should be used for the skin while a squeezer should be used for the substructure.

Cleaveland doesn't currently have a close-quarters version of this die. Mike mentioned they wouldn't be able to make them before Q2 of next year.

Sonex has 120 degree dimple die that should work for the spots you can't reach otherwise. I went ahead and ordered one:
http://www.sonexaircraft.com/eshop/cart ... ory_id=260

[PlaneDan]

I recently posted that I had gotten perfect results using the DIENQ to dimple, then up drilling to #30, on the entire wing. And, I did. However, I have discovered that it is possible for the DIENQ to NOT get the dimple deep enough, thus, not allowing the rivet to completely seat below the skin surface. I am sure this is because of something I did or did not do, but, to keep it simple, going forward with this, my plan is to stick with the -43C rivets where -42C are called for on surfaces that are clearly visible, until I run out of the -42. After that, I will NOT order any more of the -42. The -42 also have other issues, like not wanting to be used by the same nose piece on the tool as should be used for that size mandrel.

Making good progress, almost finished with the second ( left ) wing, less fuel tanks.

[psalter]

A perfectly round hole is not 100% necessary when working with rivets, as rivets do swell to fill the hole. Where round holes are most needed is with bolts, specifically bolts in high shear load areas like the wing spars. Since bolts don't swell, a close tolerance round hole gives the most bearing surface against the bolt, and there is less chance of failure. One of the reasons I pointed out the triangular hole is so people can see what a drill bit will do while drilling. And that the dimpling and reamers will usually make the hole more round.

Having said that a hole that is too large or out of shape, a rivet may not swell enough to fit. So, it is usually best to have a decent hole that the rivet will slip fit into. Making a hole so that rivets won't spin is not a design criteria. The main thing is to have a hole that the rivet will swell to fill evenly in the entire stack-up so nothing is loose. Best way to assure that is fairly round holes of consistent diameter between the different items in the stack-up. Which is one of the reasons it is best to upsize the hole through the entire stack-up instead of doing it piece by piece.

As to the use of Burr-aways, they have good points and bad points. One thing they can do, that nothing else can is deburr inside a blind hole (fuselage tubes for example), and do both sides of the hole in one operation. One bad thing is they do tend to act like a drill bit and remove more material (which actually helped some in this case). The amount of material they remove is a function of the rpm they are used at, and the tension of the tab that does the deburring. The tension can be adjusted with loosening the set screw and moving the pilot up or down. But it takes some effort to get it right.

[PlaneDan]

Actually, you need the 3/32 ( #40) Burraway for this method as you should be deburring before you use the DIENQ for dimpling. I used the method described here, where I could access the hole without having to use the "Nail Dimpler", on the entire Right wing with NO proud stems. Where I cannot use this process, I use the -43 rivet.

I would like to pose a question about the need for the hole to be perfectly round, referring to Paul's analysis. Would you be more likely to have a rivet that could not spin, with a hole that is NOT perfectly round?

[at7000ft]

Sounds like if you are going spend the $50 on the DIENQ die you also may as well cough up the $75 for a 1/8" burraway also.

Rick H

[wmensink]

[Tony Spicer]

Well, having a bit of an obstreperous streak, I think I'll throw out a dissenting opinion. Take a BSC-42 rivet and set it. Don't stick it in a dimple, just set it between your fingers. A bit of spit will prevent a burn. In the few that I did, I noted two things: The diameter on all from end-to-end was uniform and close to .162, and none had proud stems.

If somebody could tell me why the rivet wouldn't swell to fill a .135 tri-cornered hole, I'm all ears.

Tony

[rlweseman]

Excellent! Exactly what the goal is.


Rachel

[jsteere #39]

I think that it is worth using as the resulting hole is much tighter to the rivet than the standard dimpling dies. May not save time since you may still have to ream the hole, but hole/joint quality is better.

I agree with Paul about the value of this process. I do not use the burraway tool, so after dimpling and reassembling the structure, I cleco every-other hole, then, while pressing the skin against the underlying structure, I ream the holes without clecos with a #30 straight flute reamer (Cleaveland Aircraft Tool # RSF30, $9.00 each.) The amount of material removed is very small and leaves a very clean, round hole, that does not require further deburring. It takes the same number of steps, but in a different sequence than the original process, and the final hole is about as perfect as is manually possible. I have completed the tail kit, most of it with this process, with zero proud stems.
John

[at7000ft]

are you using a burraway tool for deburring?

No, I understand from Paul's report that the burraway must ream the hole a little larger in the deburring process to result in the dimpled hole being just the right size.

Rick H