Drilling HS 710

aircraft shop 487 · Post by **aircraft shop 487** » Mon Jan 18, 2010 7:39 pm

Don't let the name fool anyone. Aircraft Shop 487 is just what I wanted to call my shop. Aircraft construction is all new to me. I have started work on my rv 7a. My problem. When drilling the hs 405, hs 702, hs 404 and the hs 710 the hole came out in the hs 710 on the minimum edge distance (2X rivet dia.). In reading some of the Sport Air handouts 2.5 X rivet dia. is BEST but 2X is minimum. I have read builders web sites in the past and knew this was an area that could cause some grief. I have carefully measured this and I do have the 2X plus about .014". When I first started to measure the edge distance I knew it looked close and when I was sure I had the 2X I felt good. Later I was reading and saw that 2.5 was "best" and that just stop everything.

Is this a common outcome (2X) and is okay or should I just order some parts from Vans and shoot for 2.5X?

I go from "this is okay" to "this is also the best tiime to just order some parts"

Thanks in advance for all replies.

Gilbert

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Post by **Spike** » Tue Jan 19, 2010 8:47 am

Actually if you look at Mil Spec MIL-R-47196A published by the US Army back in the seventies, the Edge distance is generally between 1.5X and 2.0X the rivet shank diameter. We have a copy in the document share (link at the top), its a good read.

I don't know the specific parts you are talking about but it sounds like you might be ok.

Spike

PS. Welcome to Rivetbangers!

hydroguy2 · Post by **hydroguy2** » Tue Jan 19, 2010 9:37 am

you're better than the minimum. remember the lesson you have just learned and Move on........unless you are building a Gold Lindy, in which case make sure you set aside an extra $50000 and double your time estimate to finish.

dons · Post by **dons** » Tue Jan 19, 2010 12:34 pm

Welcome Gilbert!

There are a LOT of places where 2x the diameter can just be met, and several places where even that can not be met because of the design. I seem to recall a rib flange hole at the end of the long side of the 405 that 2x can not be met at all due to the design, it is not a reason to panic.

aircraft shop 487 · Post by **aircraft shop 487** » Tue Jan 19, 2010 3:23 pm

I was thinking the 2X minimum edge distance was okay. But knowing the HS 710 was critical to the horizontal stabilizer and reading that 2.5 was "Best" had me wondering. I don't mind doing the parts over but didn't want to proceed and then have all those rivets to drill out if a redo was in order. This would be the best time to fix it.

The cause. In laying the holes out on the forward flange of the HS 405 which determines the position of the hole in the HS 710 I was a little off on the top hole. Looks like a 1/32" to 1/16" off. Anyway I figured if parts were to be reorder just consider it the price of tuition. I'll move on.

I know we"ll talk again.

Thanks

Gilbert