RivetBangers.com

So I had a friend helping me cleco my tailcone together, and after we were all done, he was amazed that it all had to come apart again after it was drilled.

So here's the question: if you have two pieces of sheet held together firmly enough when you drilled, would you really need to debur the inside edges of the holes where the pieces are in contact? I liken the concept to backing up a piece of wood with another one when you drill through it so the drill bit doesn't punch out of the back of the piece you're drilling.

If it worked OK, you could prime your parts, cleco, then drill and debur with an EZ burr. Dimpling could be done with the dies held in your rivet gun and a bucking bar, and then rivet the parts together without ever fully disassembling the structure. I think this could save a ton of time, but may require two people for much of the dimpling process (just like the riveting).

An interesting idea. I think, however, you might find that you still had to pull a bunch of the pieces apart to get at the hard to get spaces and to countersink things that needed that. For instance the front fuselage takes tons of time to prep because of all the odd parts and all of the different size countersinking needed.

It might be possible to save time on the other parts of the structure though.

It's funny, my Dad comes over to help me sometimes, and he shakes his head in disbelief when I tell him it's all coming apart when we're done drilling. He can't believe I would do that.

But in my experience, I've taken apart quite a few structures after drilling, when I thought they were very tightly held together, only to find lots of drill shavings in between the pieces. Each time, I told myself "now I see why we do this."

So it seems to me, it's not just the deburring of the hole but also to clean everything up before riveting and dimpling. I can imagine that using the rivet gun either to dimple or to do the riveting would drive those shavings even further into the structure. IMHO it's a shortcut not worth taking.

I would think that Van would punch the holes the exact size. That way no drilling would be necessary, only dimpling in certain areas. Probably that would take away from the "51%" rule
Dave

The reason the holes are punched small is so the builder can drill to full size and remove the tooling marks left by the punch.  This is interesting because the holes in the RV-12 are punched to full size and Vans does not recommend drilling.  They are ready to cleco and rivet.  Maybe Vans has a new punch that does not leave a tooling mark.
 
The reason you must disassemble after drilling is to remove the burrs on the back side of the sheet.  Unless you deburr, there will be a stress point that could propogate a stress crack.  Shavings stuck between sheets will also bring problems down the road.
 
From: RB Lists - The Hangar [mailto:support@rivetbangers.com]
Sent: Friday, June 18, 2010 4:52 PM
To: hangar@rivetbangers.com
Subject: Possible time saving idea


 
I would think that Van would punch the holes the exact size. That way no drilling would be necessary, only dimpling in certain areas. Probably that would take away from the "51%" rule
Dave



rivetbangers.com - Discussion topic http://www.rivetbangers.com/forums/viewtopic.php?p=34026#34026

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I am somewhat happy that we have to drill out the punch marks. I have found times where I can't quite get an exact exact fit and use the drilling process to make things work.

The one 'down side' to pre-punch is that it can hold you to extremely tight tolerances.