Forgot to dimple for screws

[PIN 37]

Yes Steve, I would be worried about damaging the close tolerance bolt holes as well, I might try making a bucking bar, I do have access to some quite sophisticated machinery,and then tap from the bottom with a male die.

[YellowJacket RV9]

I forgot to dimple the #8 holes for the rear fuselage inspection panel screws and was unable to get my squeezer in there with the longerons installed. I cleaned the skin and then put a drop of oil over the holes, and screwed a #8 screw into the already installed nutplates, after testing on some scrap. It made very nice dimples, even after inspection with a magnifying glass. Your results may vary of course...


Chris

[7DeltaLima]

Not sure of the exact location but have you looked at the pop rivet dimple dies? Just a thought...

[PIN 37]

Yeah Doug, have thought of that, but not an option unfortunately.

[KRviator]

Is it really the end of the world If you don't install countersunk screws there? If you really don't want to try any of the (quite good) aforementioned suggestions, you could install either pan-head or AN525 washer-head screws there and wear the 0.05MPH loss in speed. You're the only one who'll know they're not supposed to be there!

[MeAndMyToys]

Originally Posted by KRviator

Is it really the end of the world If you don't install countersunk screws there? If you really don't want to try any of the (quite good) aforementioned suggestions, you could install either pan-head or AN525 washer-head screws there and wear the 0.05MPH loss in speed. You're the only one who'll know they're not supposed to be there!

I think I remember that interface is structural in shear, those counter sinks would add to the shear strength. I would contact Vans before committing to anything on those.

[Taildrgr]

Use this:

http://www.cleavelandtool.com/8-SCRE.../#.VtL2w5X2aUk

The die won't rotate and spall the skin.

[Mel]

Originally Posted by Taildrgr

Use this:
http://www.cleavelandtool.com/8-SCRE.../#.VtL2w5X2aUk
The die won't rotate and spall the skin.

^^^THIS^^^ is the answer. I use "pop" rivet dimpling pretty much exclusively.
I have several tools similar to these that I made years before they were commercially available. The only difference between these and mine is that I tapped the female die so you don't have to use a back-up nut.

[rv7charlie]

Originally Posted by rv7charlie

I'll try to measure for you when I go down to the hangar in the morning. Do y'all have the equivalent of Harbor Freight Tools down under? You can get 'good enough' digital calipers for less than $20 US; often much less. Old style dial are often under $10.

But I seriously doubt it will be an issue, even if they're .040.

According to my Harbor Freight calipers, the fuselage belly skin is .025" & the wing bottom skin is .032".

If you're building a show plane, the Cleveland die would help make a perfectly edged dimple. But you should be able to come pretty close with just a screw.

For something 'in between' in quality and a lot quicker to get, you could drill & dimple a 1" disc of .040", & use that as your die under the head of the screw. Just whack the daylights out of it in your C-frame to be sure you get a good sharp edged dimple on the homemade 'die'.

Charlie

[Billythekid]

I can't wait to make it these mistakes. It's only the ability to reason that wears so thin. There something to be said for doing something the second time...or third. I read these mistakes and it makes me laugh cause I know there is a day or 50 when vans universe is laughing at me.