Shawn's RV-7 (Desert Garage Works)

[ShawnAM]

So I ended up with some oblong holes after match drilling the HS parts.

I have measured all holes against the table of rivet hole sizes specified in MIL-R-47196A : max hole size #40 is .103 in. and #30 is .135 in.

The holes makes with numbers in the following pictures exceed the maximum hole size and must drilled up to the next size.

First is HS-00001 both right and left side. Am I able to "repair" this many holes this close together? (3 holes in a row on left side HS-00001). Or, should I start with new parts? If I go the route of new parts, I will still require repair of the hole marked #1 on each side (oblong hole in HS-702s as well), unless I replace both HS-702 also.





Second is both HS-707 ribs:

LEFT





RIGHT:



I sent an email to Vans to see if these holes can be drilled up or if I should order new parts.

[Girraf]

Not ideal but if those holes are cause to scrap the parts, I'd be shocked and would have to re-evaluate my own standards of acceptability in my project. The worst offense I can tell is hole #1 on the doubler and MAYBE would consider replacing it due to its importance. Curious what Van's has to say.

[nzrv8]

Hi Shawn,

Van’s approve the mixed use of solid and cherrymax rivets in the SB, and you can get cherries in slight oversizes, it may save you going up a full size for a solid rivet? Let us know what Van’s says.

Hugh

[BillL]

These parts are pretty important structurally. Vans will offer the best advice, but you could scratch make some replacement parts of needed.

[sblack]

There are MS rivets that are oversized just a bit - 1/64" or so. Then there is the next size. Generally if the spacing is more than 2D (D is rivet dia) there should be no issue with going up a size. For minimum spacing consult AC43.13. Certainly you want a round hole, so you will have to go to a larger rivet, but I don't see any need to scrap it. I am an aero eng and have taken a bunch of rivet design courses back in the day, so I have some idea what I am talking about, but I don't work as a structural engineer and you don't know me from Adam so you shouldn't listen to me. I am simply posting to prevent unnecessary suffering while you wait to hear from Vans. I strongly expect that they will tell you to go up one size and build on. Also, try to figure out how you managed to do this so you don't do it again! (duh).

[JonJay]

What kind of drill and drill bits?

[ShawnAM]

So Vans basically responded by referring me to SB-14-01-31. It addresses oblong holes on pg. 20 by basically saying drill any up 5/32 and use regular or cherry max rivets. On the next page, 21, it addresses edge distance. So the basic consensus seems to be drill up in size unless edge distance presents an issue.

Edge distance is where I noticed a problem. If you at the right hand HS-00001, hole #3 goes through the lowermost hole of the forward rib flange of HS-00005. Edge distance is exactly enough for a 1/8 rivet. So I can't enlarge to a 5/32 and am assuming I will need to replace any with that particular hole enlarged.

The left hand side of things should be fine. The three holes I am looking at drilling up to 5/32 (#21) present no edge distance issues. The distance between the rivets are all greater than 5/16.

[ShawnAM]

Oh, and all of the oblong holes were drilled using this right angle air drill and Cleaveland threaded drill bits (the longer ones). I was starting my holes using HS-00001 as a guide rather than the thicker side at HS-714.

It just seemed like the bit was not actually drilling into the material but just spinning in place. As I pressed harder it began to wobble which is what I think led to the oblong holes.

Now I am making sure to start each hole by hand in the exact center of the hole or use a center punch where applicable.

I am also looking at making some drill guides.

[Ender]

If you are using a right angle drill on those parts above, I would stop (unless I'm missing something).

Its not the easiest to line up and keep lined up (control) those drills (on comparison to a normal air drill).

I only use the 90 when I absolutely have too (when space or the angle doesn't allow for a stnd drill/bit.

Using a normal hand drill also allows you to use the reflection of the bit on the piece to keep everything centered.

[JonJay]

Enders makes a good point about The 90 deg drill. If you think about how short the business end is and how long the body is, it takes very little “twist”’and the bit will be wobbling. You also have figured out using thin material as your “guide” led to more problems.
Keep swimming !