G

gbumga

Active Member
I'm almost sure I screwed up on the first parts of my emp work. It says in the manual to smooth all surfaces and remove scratches,radius end R-1/4. These are parts HS-609PP and HS-710/714. I did all but HS-714. After reading a post on edge dis. I checked the ends and most don't have 2X the rivet diameter from edge to center of the rivet hole, some 1/32 short some 2/32. 2X the rivet dis. is 1/4" and all I did was remove the dad-dang machining marks! I measured HS-714 which I haven't work yet and it is exactly 2X the rivet dis. It appears I can't so much as breath on the ends without taking to much material off,all you can do is do the R1/4" on the end sides and totally leave the end material as is or you have lost your min.edge distance on the ends of these parts. Since these are spar reinforcment bars even I know there critical parts not to be fudged. First am I seeing this correctly and if so why the heck is it so close from the factory and why wouldn't there be a warning not to mess with the ends when this is the first thing you do and being a beginner? it says smooth the marks and you can't at this spot on the part. I'm upset but at least I found out there was a problem and can regroup. Bottom line are these parts junk,I think so. Tell me I'm wrong. Gene
 
well Id hang on before jumping to conclusions. I have seen quite a few places in my kit that do not have 2D. Youll need to decide yourself just how "perfect" your plane is going to be but 1/32?! Ill go out on a limb and say that 1/32 off of perfect edge distance will not be a big problem. besides if all you did was take out the tooling marks, if you had left them you would have had tooling marks on your "perfect" plane and we know that there should be no stress risers on our parts soooo........give vans a call, they will either make you feel better about leaving it or youll just order a new set and chalk it up to your first reorder. Dont feel bad my first spar doublers got thrown out in the trash before I knew they were sandwiched in the box of parts, so I got to spend another 100 right off the bat.....what can ya do..
 
Before you panic, have a look at this document:

http://www.vansaircraft.com/public/Specs.htm

This is the Mil-spec on riveting. Everything you ever wanted to know about rivets but were afraid to ask. You will find that the 2X is a rule of thumb, and a good conservative one. However, a close read of the spec shows that the minimum edge margin in your case is .219, not the .250 required by the rule of thumb.

So, why not go with the more conservative rule of thumb? Well, because rivets that may well pass muster according the the Mil-spec would be rejected if the rule of thumb were followed as Gospel. And, as you will soon learn, drilling out a bad rivet often causes more harm than good, so it is senseless to try to drill out a rivet which meets the spec.

Build on.
 
Gene,
I remember finding myself in exactly the same situation a year and a half ago. In my opinion the design simply does not allow for a decent edge clearance. I had my inspector (we have inspectors from the LAA here in the UK) take a look at it and he was happy that it would be OK. He didn't think there was anything I could have done better.
Steve
UK
 
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