To match drill or not?

Lycosaurus · #1 10-09-2008, 07:30 AM

It was interesting to hear on another thread, that some people did not match drill and deburr their parts, but went straight to dimpling and riveting. Maybe this poll will give us a glimpse as to the percentage or number of builders that went that route.

I, because I am me, match drilled, deburred, dimpled, washed, etched, alodined, and applied 2 part epoxy primer everywhere. I feel so foolish

I would be interested to hear from those that did not match drill/deburr, to see how many hours they have on the airframe, and if any cracks (or other related issues) have propagated from those holes.

Please, no flaming .... just the facts.

DaX · #2 10-09-2008, 07:52 AM

Drill, debur, dimple, rivet.

I am only scotchbrite-ing and priming places where two pieces of metal touch each other, and all non alclad parts (these also get acid etch and alodine).

Mel · #3 10-09-2008, 08:09 AM

No holes came in the 1989 vintage kit! Not even lightening holes in the ribs. You guys have it tooooooo easy!

Lycosaurus · #4 10-09-2008, 08:17 AM

Quote:

Originally Posted by Mel

No holes came in the 1989 vintage kit! Not even lightening holes in the ribs. You guys have it tooooooo easy!

Very true, but it's all relative, Mel.

I tell my quick-build buddy (he didn't even have to build the fuel tanks) that he had it so easy, compared to my "slo-build". He tells me his kit is so much more work than the "two weeks to taxi" program.

Then again, you had a kit... so much easier and faster to build than the RV-3 plans built from yesteryear.

allbee · #5 10-09-2008, 08:19 AM

On new pieces, I would strip the plastic, resize the holes with a reamer, than did a quick debur on the opposite side or rough side, dimple , hit the edges with a quick file, assembled the parts and riveted. I found that the prepunched kits are right on, once in a while I would find a rivet would not fit, I hit that hole with the reamer, then threw in the rivet and set it, than moved on. The only time I took things apart was when I needed to drill for new holes, I call this match drilling. I took the pieces apart to clean the garbage off on the opposite side of the drilling.

I did do a little priming in the back section, or tail. What I did there was clean the surface and hit directely with etch primer from Napa, no scotch brite.

N941WR · #6 10-09-2008, 08:39 AM

Even with as good as the pre-punch kits are, there is still some slight variation in the hole patterns. Match drilling aligns the holes and helps reduce stress between the rivets.

Will going straight to dimpling cause the plane to fall out of the sky. Nope but what no one really knows is the long term effect.

"They" say it will cause small stress cracks to form but I would wait to see a 2000 hour RV that was built this way before passing judgment.

However, since we don't have those 2000 hour match drilled RV flying around just yet, I would and did match drill, deburr, dimple, and then rivet as I hope to keep this plane a long time.

airguy · #7 10-09-2008, 08:58 AM

Quote:

Originally Posted by N941WR

Even with as good as the pre-punch kits are, there is still some slight variation in the hole patterns. Match drilling aligns the holes and helps reduce stress between the rivets.

Will going straight to dimpling cause the plane to fall out of the sky. Nope but what no one really knows is the long term effect.

"They" say it will cause small stress cracks to form but I would wait to see a 2000 hour RV that was built this way before passing judgment.

However, since we don't have those 2000 hour match drilled RV flying around just yet, I would and did match drill, deburr, dimple, and then rivet as I hope to keep this plane a long time.

Same here - I'm limited by funds on my building time to somewhere around 3 years - so I've got time to do it right. That means drill, deburr, and prime all contact patches.

Tkitchen1 · #8 10-09-2008, 09:06 AM

Grettings all. when a piece of metal is punched, it tears out on the bottom side (die side) This tearing creates micro cracks at the edges. It also creates stress risers in the metal. Match drilling removes the punch tears and helps reduce the stess risers. Deburring remove the tiny little sharp edges that also have micro cracks. Although drilling does not remove all stress, It reduces probabilities. The second part of this equation is that when the rivet is set, it swells, if the hole is just big enough to get the rivet in, when it swells it could buckle or distort. All of this being said, all of the drilling and deburring does not eliminate potential cracks and failures, it just reduces the probabilities.

rv7charlie · #9 10-09-2008, 09:38 AM

When I started building, I made test samples using scrap pre-punched stiffeners.Some I dimpled 'raw', some I drilled/deburred/dimpled (with 3flute debur tool), some just deburred/dimpled. If you try it & examine each with a magnifier, I'll bet you'll be surprised at what you see.

I've heard that the RV-12 kit instructions just say to assemble & rivet (no match-drilling). Anyone know for sure?

Charlie

Don Jones · #10 10-09-2008, 11:42 AM

I always drill, (ream actually), de-burr, dimple and sometimes I skip the match drill thing. Depends on what I am working on.