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RV-7 HS-405 Sec D-D Drilling Help

F

flyingtaran

Member
Hi All
i have hit my first wall, i am on the Horizontal Stabiliser and got up to the "Drilling The Horizontal Stabiliser" section. on step 2 under "Drilling The Horizontal Stabiliser" it states "using the dimensions given in sec d-d, mark the hole locations on the forward flange of hs-405." etc.
I have read and re-read this multiple times unsucessfully and spent hours reading trying to figure this out.
Any help or pictures would be much appreciated

IMG_0780.JPG


Thanks
 
The upper hole is simple: "maintain min. edge distance".

The two center holes need to be drilled in a way that maintains edge distance on HS-404. Note: When you trim HS-404 start by trimming less than it says in the plans, and only trim more if you have to.

The bottom hole is relatively uncritical, and the plan says it's at 1/2 inch below the upper edge of HS-814-1 (disclaimer: I'm building an -8).

Again, make sure to maintain you edge distances on all the parts (including HS-404!), and you'll be fine. Having said that, my distances are:

1st hole: 1/4 from the top edge of the flange
2nd hole: 7/8 from the top edge of the flange
3rd hole: 1 1/8 from the bottom edge of the flange
4th hole: 5/16 from the bottom edge of the flange
 
Not sure if this helps, but I discovered something while I was at it. (From 12/31/2009)

...I seem to be having edge distance troubles on the HS-405 and HS-702 spar. I checked everything and it seems to be right. I checked some other build sites to see if other people have run into this, no one mentioned it. Right as I was going to post a question on the forums about this, a new thread popped up. Apparently this is a common problem, and the edge distance on HS-405 is not to be worried about (someone called Vans in that thread). It?s a little confusing, though, given the prepunched nature of the parts...

The next day, I clamped HS-404 in place after having first marked holes and drilled #40 pilot holes in the aft flange. The instructions have you (measure), mark, and drill pilot holes in the HS-405, but why drill from aft to forward, hoping you don?t run into edge distance problems when you could drill from forward to aft? For the outboard holes, I did use the HS-405 for pilot holes.

This worked for me, but like everything, your mileage may vary.

Couple pictures:

http://n999za.files.wordpress.com/2009/12/12-31-09-093-large.jpg
http://n999za.files.wordpress.com/2010/01/1-1-10-003-large.jpg
http://n999za.files.wordpress.com/2010/01/1-1-10-005-large.jpg
 
Good point about drilling the HS-404 holes from the front. That's probably safer. I did it the other way round, but made dead sure that I will have enough edge distance -- the key here was to start trimming HS-404 much less than in the plans, then retrim as needed.
 
HS center section pic

Here's a pic that might help. I made sure the middle holes that attach 405 and 404 were a little closer to the middle (vertically) so I had edge distance after trimming 404. I spent a lot of time as I'm sure others did measuring and re-measuring, especially for the edge distance on HS710. The oversize rivet head is an oversized 5- rivet. I had a hole that wasn't perfect so I enlarged it to the next size up rivet. I had the best success pilot drilling and then drilling to final size using the very long drill bit as another poster shows. (the bendy one!)p.s. yes I did mess it up once and replaced a bunch of parts...
2wh1952.jpg
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Scratched my head too at the time.

I have had the same considerations reading those plans. Taking the dimensions as on the plans is certainly not giving you the sufficient edge distance.
Vans will tell you that it is not a big deal as in more places further on, you will encounter that sometimes edge distance is forgotten.

However, the risk is that while drilling you get even more wrong en then it becomes a scrapped piece.
I described how I did it on my website with some pictures under the section empenage, horizontal stabilo, article Assemblage left stabilo 03/01/2011 - 07h45

see www.jursrv7.tk

For the reinforcement angle rivets to 405, the dimensions on the plans are ok.
The most problematic is the holes in the leading edge rib en HS405, or differently stated: where will you end up on the leading edge rib tab flange and will you be ok on edge distance?
The trick is, clamp some aluminum sheet on the flanges as temporary skin to align the parts, then draw the location where vans want's you to drill, you will soon find out it seems to be pretty close to the edges.
If you determine your drill point from the leading edge rib, and project that on the 405 to start drilling from that side once attached to the front spar, you will be fine when coming through on the other side.

emp-hs-6-2.jpg
 
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Need to pay special attention to the edge margin (or edge distance). If trimmed to plan, there is no room for error. Don't drill holes on either HS404 or HS405 before fitting them and making sure edge distance is ok. You might need to move the center two holes closer than specified in the drawing to maintain edge distance.
 
To clarify my ealier post.

Indeed NO drilling before the thing is assembled. But, do mark the dimensions of the plan upfront on the parts like I did, you will see that you may have to move the inner 2 for edge distance. (depending on how generous you were in cutting the flanges before)
 
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