Punched Hole Sizes

[Michael Smith]

Hello everyone. Many years ago, when the RV-4 was first introduced, I purchased the tail kit and finished the horizontal stabilizer before work pressures forced me to abandon the project. Now I am prepared to start anew -- probably on an RV-7 -- and I am delighted to see that Van is using CNC equipment to pre-punch the holes in the wing skins. Two questions:

1) Are the corresponding holes also pre-punched in the ribs?

2) Why are the holes punched .003" - .004" undersize, thereby requiring the builder to ream or drill to the correct size?

Thanks in advance for any response. This is a wonderfully useful forum for those of us new to homebuilding.

[cjensen]

1) Are the corresponding holes also pre-punched in the ribs?

Yep!

2) Why are the holes punched .003" - .004" undersize, thereby requiring the builder to ream or drill to the correct size?

I believe it has something to do with time of punching the parts. If they had to change punch bits for each size hole, it would add significantly to the cost of the kit. Plus, it would take away some good building experience!

Thanks in advance for any response. This is a wonderfully useful forum for those of us new to homebuilding.

This is the best place on the web!!

[johnk]

I remember reading that the punching process can create tiny cracks around the edge of the hole, that can grow into large cracks over time. Drilling the punched holes removes the metal around the edge that contains the tiny cracks leaving a nice crack-free hole.

[cjensen]

Oh yeah! I do remember reading that as well...

[Michael Smith]

Gentlemen, thanks for the response. And thanks to whoever created RivetBangers.com; it has TONS of useful info for homebuilders.

[cjensen]

And thanks to whoever created RivetBangers.com; it has TONS of useful info for homebuilders.

That would be Mr. Spike! Mastermind Chief Rivetbanger! We all thank him all the time for creating this Vunderful Place! Like the shirt says-We're building more than just RV's!!

[Spike]

Glad that I could be of help guys. The only think I ask in return is to bring more people so that it can become even more useful for community.

[JohnR]

Glad that I could be of help guys. The only think I ask in return is to bring more people so that it can become even more useful for community.

I want to throw i na thank you also Spike. I tell everyone who may be interested about this website. Thanks!