How deep is 1 inch deep?

[mvidalr]

Hi all,

I'm having trouble trying to sleep, and couldn't find a post related to this issue.
Place yourselves in the early stages of wing construction. For those models with the W-731 type AEX stock tie-down bars, the drawings (15A) call for tapping the hole for the tie-down ring 1 inch deep.


This 1 inch is not enough for the ring's shank to travel til stops, therefore leaving about .478" (15/32") threaded shank exposed. (Pics below)


Is this excess normal? Is there also a "best" orientation for the ending ring (parallel/perpendicular to airstream-EVEN IF only used when grounded)?
Or should it stop at the W-731 TD bar like this? (credits: www.rv7factory.com)


Am I overthinking this because there will be something between the TD bar and the base of the TD ring that I'm not aware of?

Thanks folks

[Jerry Fischer]

Just the wing skin between the end of the tie down fixture & the ring itself...I couldn't sleep either ;-}

[Vern]

If it bothers you, drill some more so that the rings are flush with the skin. That 1" spec is not critical. Another 1/4" won't hurt a thing.

[terrykohler]

Vern is correct. I tapped mine deeper as well. When you're putting the ring on any time afterwards, just make sure that it isn't tightened so much that the flange comes in contact with the skin. This is especially true after painting - the contact will result in scraped paint around the hole. If anyone is helping me during tiedown, I tell them to leave about 1/4" of thread showing so as not to damage the skin. The ring will still turn, but that won't matter when the tie-down ropes are attached. At the same time, you need sufficient thread engagement when you're using these as jack points.
Terry, CFI
RV9A N323TP

[Michael White]

Originally Posted by terrykohler

Vern is correct. I tapped mine deeper as well. When you're putting the ring on any time afterwards, just make sure that it isn't tightened so much that the flange comes in contact with the skin. This is especially true after painting - the contact will result in scraped paint around the hole. If anyone is helping me during tiedown, I tell them to leave about 1/4" of thread showing so as not to damage the skin. The ring will still turn, but that won't matter when the tie-down ropes are attached. At the same time, you need sufficient thread engagement when you're using these as jack points.
Terry, CFI
RV9A N323TP

I think Terry's response is right in line with Van's thinking...if you tap it 1" deep and the ring bottoms out before the ring flange gets to your painted wing, then you don't have to tell somebody to leave a 1/4" of thread exposed to save your paint.

From a mechanical standpoint, 1" of thread engagement is more than sufficient for the tie-down ring. Nothing short of a Sun-n-Fun tornado is going to rip it out.

[Bob Axsom]

You can also grind off the end of the tiedown ring shank. I align them so the smallest possible profile is facing the line of flight. I leave them in for travel but take them out and cover the holes for racing. I run them all the way in and made a 0.016" spacer (looks like a washer) for low drag alignment on the right ring shank. Imron paint, ~8 years & near 1,000 hours no paint damage yet.

Bob Axsom

[Flyguytki]

Another way to prevent scratches is to slide a rubber grommet over the shank of the tie down ring, it provides a nice cushion between the shiny paint and the rough metal of the ring.

[aerhed]

Also works to drill the skin hole just large enough to install a check nut. Saves the paint, gives you a way to index the ring, and fills the last of the threads making it less likely to snap off.