Elevator CS4-4 Dimple / Countersink (RV-7)

Hi All,

I am currently wrapping up my right elevator and on page 6-9 of the instructions (Preparing the Right Elevator) the last step states that you should "Deburr, dimple and prime the parts as desired". I presume during this step you should also drill with #30 and dimple the outer edge of the E-701 skin and E-713 counterbalance skin for the fiberglass tip installation later on? I imagine that dimpling the section where E-701 overlaps E-713 once the elevator is assembled could be very difficult.
Also, I noted that the CS4-4 blind rivets used to attach the fiberglass tip have a 120 deg head rather than the 100 deg present on AN426 rivets. Is it OK to dimple these just with a normal 1/8 dimple die? I sure hope so, as I didn't have anything else. It is interesting to note that the Tools List only specifies a 120deg countersink cutter for the RV-14, however the RV-7 appears to be riddled with these CS4-4 rivets. Is it OK to use the 100deg #30 countersink cutter, or should I wait for my 120 deg cutter to arrive from the US (I live in Tasmania, the last stop before Antarctica, so they could be a while).
Sorry for so many questions (it's been bugging me all day), so I'll throw in an executive summary:
1. Should I have dimpled the E-701 & E-713 for the CS4-4 before riveting the elevator together?
2. Is it OK to dimple for a CS4-4 with a traditional 1/8 dimple?
3. Is it OK to countersink the fiberglass tip with a 100 deg CS, or should I wait for the 120 to turn up?
4. Should I go back and read the instructions again, because someone's going to tell me it's all in there somewhere and I missed it?

Thanks for your help. I really don't know how anyone built an aeroplane before the days of Vansairforce (thanks Doug). I guess I could have called Van's, but I thought if I post this here, hopefully the result helps someone else in the future.

Cheers,

Tom.

Help

Tom
1. I did for that very reason but I left all fiberglass work to do at the end.
2. I did. Seems to work but maybe someone else with more skill will comment.
3. I read a post where someone made a fiberglass countersink cutter from a dremel stone bit. Fiberglass is hard on tools so I like this idea.

I also did 1 and 2, but intend to leave fibreglass work to the end.

Help

1. I did not. I wanted to able to fit the fiberglass tip, drill #40, adjust and then drill to the final size.

2. I did

3. I used a dremel stone bit, worked great

4. The plans mention installing the fiberglass tips at the end of the chapter, but it does not address you questions.

I used CS4-4 rivets on my elevator tips, but at the trailing edge those last two rivets get difficult to set. If I were to do it again I will use CCR-264SS-3-2 rivets on the last two, with CS4-4 on the rest. Vans sells them, you can probably find them a lot of places. It is a steel, flush 3/32 blind rivet.

EDIT: By last two I mean the last one on top and on the bottom of the elevator where the tip attaches.

You should have received what appears to be scrape pieces of aluminum, .020 thick cut in thin strips. I epoxied those to the inside of the fiberglass tips for additional strength. If you search through the fiberglass forum there are lots on threads on this very topic.

But if you don't find what you are looking for, ask more questions. That is what the forums are for. I have saved a lot of money by asking questions.

Thanks

Hi Guys. Thanks all for getting back to me so quickly. A huge feeling of relief, as getting replacement parts out here is **** expensive (yes, I'm onto my third HS-702 - how I hate relief notches). I particularly like Scott's reinforcement ideas and smaller rivets at the tip, however since I drilled and dimpled for a #30, that train has already left the station. Anyway, thanks again and it's good to know that you don't have to do all the head scratching on your own, even if you are 10,000 miles from the home base!
Cheers.
Tom.

Tom

I did not dimple these holes yet. On the rudder the instructions specify to dimple a few of these holes that will be particularly difficult to dimple later. I believe the inference is that the rest should not yet be dimpled. I think it would be very difficult to fit the tips with the dimples there. I'll be finding out much later though.

As for the need for a 120 degree dimple or countersink I have recently seen this in the aileron instructions:" The countersink need not be 120? to match that of the rivet heads. The .020? skin and the aluminum blind rivet will deform sufficiently to contour to a 100? countersunk hole."

It's not quite the same situation but vans has a habit of scattering this type of wisdom around, so I think it would apply to most applications of a 120 degree blind rivet. If I were moving forward with the fibreglass stuff now I would just stick with 100 degree stuff.

Tom,
If or when it comes to dimpling those trailing edge rivet holes later, you can make a female dimple die in a piece of steel flat bar. Put the bar in a bench vice, get a helper to hold your part over it, and use your male die and a small hammer to smack it.

There`s plenty of RV`s in Australia and your local SAAA guys will hook you up with all the advice under the sun.