[K?hler]

I set up my microstop last night but decided I was tired and it would be better to start the actual machining first thing today. Sadly, I guess I'm not a morning person. I tested my first line of countersinks and saw daylight between the skin, so progressively went deeper until I concluded that it would never sit flush. "Then" I did some searching and found that this may be a familiar story for many of you.

Anyway, looks like I'm about .010 too deep on the rear spar. I'm guessing that means a call to Vans in the next few days for some new parts. Bummer.

Anybody DRDT-2 dimple the spars? Alternatively, if I machine c'sink again, is it generally accepted about 3 clicks past flush? (That seems to be what I measure dropping a rivet into the female dimple die.)

 

[Lionclaw]

I did the same on mine and had to order a replacement. If I had to do it again I think I would consider dimpling.

I dimpled my flap and aileron spars and they deformed a bit (curved) but the skins pulled them straight once they were clecoed on.

Did you csink all of your holes? If not, you could try test dimpling the remaining ones and see how it turns out.

 

[K?hler]

Thank you for the reply Andy. I was pretty bummed out over messing up. (I was going to be the guy that got through this without needing any replacement parts! ) In retrospect it was silly to try to outsmart the instructions and re-invent the wheel.

I later did a couple section cuts through some rivet joints at various countersink depths and now better understand what's important. Count me among the "shallower is better" camp. The overdepth countersinks give what looks like a nice fit on the outside, but with gaps internal to the joint. Seems like that would be hard to detect once built - I wonder how many are flying around like that.

Anyhow, new parts on the way and lesson learned. Make it right. Fifty bucks and move on. Education and recreation...

 

[647jc]

What I found helped was to be sure and get a good crisp dimple in the skin fitting over the spar, otherwise the dimple will not want to sit down flush into the countersink unless the countersink is deeper than normal.

 

[paul330]

I redid 2 VS spars (for other reasons). Now I have some scrap which is thick in places due to the doublers. So it is perfect for testing the c/s depth. I have also made several dimple guages for 3/32, 1/8, #6 and #8 so I can check the depth is correct.

I disagree that slightly under depth is better - the skin simply won't sit properly. That's somethng I discovered on my test piece. A couple of thou over and it will all get pulled in by the rivet for a nice finish. Obviously, you can go to extremes.

You need to get this skill right before you start on the main spar..........

Good luck - I'm going to need it tomorrow - starting riveting on the wing bottom skins

 

[haydnc]

VS-808 counter sink

Hi,

I think i have a simular problem,

I have machine countersunk the vs-808 rear spar doubler, dimpled the VS-803 rear spar (with pneumatic squeezers). When the dimples sit inside the countersinks I can see daylight between the spar and the doubler.

When countersinking, I went 2 clicks past flush as Vans suggests.

Do I need to countersink deeper?