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Am I reading this correctly?

Roy25101

Active Member
I just started on the tail section of the -12 and am quite surprised to see that the holes in the skins and most of the ribs and spars are already punched to size. Is it safe to say that these factory holes do not need to be de-burred? I have previous experience with the tails of the -10 and -9 and both of these kits required that the sub-structure be clecoed together, the skins clecoed in place, and every hole be drilled to final size. Then the entire thing is disassembled and all holes de-burred before final riveting. I cant find anything in the manual that indicates anything other than de-burring the edges of the skins then riveting them in place. I just wanted to throw the question out before I made a permanent mistake.... Thanks in advance.....
 
Having deburred thousands of holes on an RV-9A, I know where you?re coming from with regards to deburring. However, Section 5.2 says, ?Holes that were factory punched to final size can be inspected and only deburred if needed (with the exception of large holes to be dimpled for screws).?
 
I found that the sheet punching process that Van's uses tends to create a very small burr on only one side of the hole or cut-line. A very light deburring here may be appropriate or even a quick swipe with a Scotchbrite pad to knock down the burr. Remember, these are relatively thin sheets and a light touch deburring is required.
 
I found that the sheet punching process that Van's uses tends to create a very small burr on only one side of the hole or cut-line. A very light deburring here may be appropriate or even a quick swipe with a Scotchbrite pad to knock down the burr. Remember, these are relatively thin sheets and a light touch deburring is required.
Ditto, my experience and procedure exactly. The thicker bracket-type parts tend to have larger burrs so I always debur those holes.
 
ROY2501

Unlike the '9 there are very few holes you will need to drill to the correct size. I'm about half way through the fuse kit and maybe i've had to really drill just a few dozen holes to size.

But....I've needed to pass a #30 reamer through almost all the holes as the #30 pull rivets can be a tight fit. Sometimes i'd have to debur after that (but not often).
 
I've needed to pass a #30 reamer through almost all the holes as the #30 pull rivets can be a tight fit. Sometimes i'd have to debur after that (but not often).
What you're describing has been my experience, too. Usually the LP4-3 rivets will fit through the holes in the individual pieces, but as soon as I cleco the pieces together, the rivet no longer fits, even if I put a cleco in every hole. When I run the reamer through the hole, it barely removes any material, but it's just enough that the rivet fits perfectly.

I've debated whether I should deburr after using the reamer, but the reamer takes off such a small amount of material, I didn't think it was necessary, especially on thin skins. I hope I made the right decision.
 
If you can ream with the 30 chucking reamer on the backside of the punched hole you can save any additional deburring on that side. Also helps when clecoing parts together to space a few holes with rivets first(don't pull) before inserting any Clecos. Yes,the holes are that precise..
 
General rule: Always inspect parts before assembling them. Never assume something's good without verifying. Check for burrs and if you find one, remove it.

The punched holes on the RV-12 kits are practically all final-sized. The LP4-x pulled rivets may vary somewhat in diameter from batch to batch per the manufacturing spec, so at times it's necessary to ream the hole to open it up only slightly to allow a rivet to be inserted. A final-sized hole does not imply a guaranteed-burr-free hole, so you're expected to check for burrs and act according to what you find.

Pulled from KAI Section 5:

All drilled holes, or prepunched holes that have been final-drilled to a larger size, should also be deburred. Holes that were factory punched to final size can be inspected and only deburred if needed (with the exception of large holes to be dimpled for screws - see below). This is an easy but time-consuming chore, and can be done with an oversize drill bit, either held between your fingers and twisted, or in a variable speed drill running very slowly. Special swivel deburring tools are also available from tool supply houses. These work better and are much quicker. Burrs around holes are a problem mainly in riveting and dimple countersinking. The burr can prevent a rivet head from seating properly and can make dimple countersunk holes more prone to developing cracks radiating from the hole. Many novice builders deburr excessively deep. Deburring should not produce a significant chamfer/counter-sink on the edge of the hole. Be particularly careful deburring holes in .020 or thinner sheet. By the time both sides have been deburred the hole could be enlarged.

That section (Section 5) is quite possibly the most important section in the plans. We consider it to be the foundation, and madatory reading before anyone starts to build.
 
Having just finished two RV12's and thoroughly enjoyed the process, I can say that you will end up clearing about 25% of holes, particularly on wings or whenever the skins are taking a reasonable curve.

Never bothered with a reamer, sharp new super cobalt, as others say, you sometimes can't see anything coming off and I think it is the variance of the pulled rivets.
 
Having just finished two RV12's and thoroughly enjoyed the process, I can say that you will end up clearing about 25% of holes, particularly on wings or whenever the skins are taking a reasonable curve.

Never bothered with a reamer, sharp new super cobalt, as others say, you sometimes can't see anything coming off and I think it is the variance of the pulled rivets.

Indeed, there is a fair amount of variance in the diameters of the LP4-3 rivets. I have a box labeled FAT FOURS where I put these for later use in holes which, for whatever reason, seem loose. When a rivet won't go, I first try a different rivet.

JH
 
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