How to enlarge a large hole?

mill2978 · #1 07-15-2013, 04:47 PM

I ordered the RV-14 fuel tank caps for my RV8. The rivet holes align and it sits flush on the skin, but I need to open the hole for the cap ~.2 inches.

The current hole is ~2.34 inches and the final hole needs to be ~2.54 inches.

Is there a recommended technique to accomplish this?

My initial thought is to cleco a plate over the top of the current hole, find the center, then use a hole cutter to cut to the final size.

plehrke · #2 07-15-2013, 05:11 PM

Cut out a piece of plywood with correct size hole and clamp to part. Use router or zip cutter to cut hole with plywood as guide.

rzbill · #3 07-15-2013, 05:26 PM

If you are skilled with a file, you can scribe the line and file to it. A craftsman can do it so well it will look machined.

g zero · #4 07-15-2013, 05:36 PM

Drum sander on a hand drill . If you own a Cleveland tool edge roller that will put a nice finishing touch to that area also .
Tom

Bill_H · #5 07-15-2013, 05:46 PM

Dremel with small drum sander head.

cfiidon · #6 07-15-2013, 06:08 PM

Use a square to draw perpendicular lines tangent to the existing hole. A straight edge from corner to corner (tape thread) will give you the center of the hole.

Use a compass to draw your correct diameter circle and center it. Trace the new circle.

OR

Use a compass to draw two circles (old and new diameter). Center the old circle on the hole. Tape the paper template in place. Cut out the old hole. enlarge the edges to the new hole. Should give you a nice round hole if you use a sanding wheel, file, or edge dresser.

Don

tweiss · #7 07-15-2013, 06:45 PM

Great thread!
I just got my -8 wing kit last week and ordered -14 gas caps with it as well.
Glad to hear that the tank skins already have the rivet holes in them, and even better that they line up with the -14 caps.

I've been contemplating how to get this hole enlargement thing to happen.
So far the best idea I've heard in my local circle of knowledge is to cut a fresh piece of plywood big enough to cover the cap hole.
Clamp it down flat to the tank skin.
Then find the center of the cap hole and and mark it on the plywood.
Drill through the skin and plywood with a hole saw type cutter using the plywood to guide your pilot drill at the center of the hole.
Hope that makes sense.
Looking forward to hearing all the other ideas here as well. I'm not even going to open my box until fall except for a quick inventory, then close it back up. That's the deal with my wife. "winter project" One sub kit per winter. Did the tail kit last winter.
Good luck, and thanks for the great question.
Tom

JanRV6UK · #8 07-16-2013, 05:09 AM

Before going down the hole saw route - do it on a scrap piece first - you may not like the edge and accuracy of the hole saw you are using ... When I have enlarged large holes I have found that a new sharp scribed circle - with a 1/4 to 1/2 size sanding drum was the best way to get a perfect hole .. just sanding out to the scribe line ... perfect hole. It is harder to get a nice hole if the file has a small radius in comparison to the finished hole radius ...

izzybear · #9 07-16-2013, 08:16 AM

I have tried to follow the various links and have read as much as I can find on it - but can someone tell me what the advantage is to going to the "new" -14 cap on the RV-8 tank? I am at the tank building stage and I ordered the deluxe caps (for the -8) when I ordered my wings...it's not too late for me to change to the -14 caps at this stage in the build, but I don't see any discussion on the pros/cons, just whether or not they will fit the -8 or how to drill out the hole??

Thanks for the help...

mill2978 · #10 07-16-2013, 08:36 AM

Quote:

Originally Posted by izzybear

I have tried to follow the various links and have read as much as I can find on it - but can someone tell me what the advantage is to going to the "new" -14 cap on the RV-8 tank? I am at the tank building stage and I ordered the deluxe caps (for the -8) when I ordered my wings...it's not too late for me to change to the -14 caps at this stage in the build, but I don't see any discussion on the pros/cons, just whether or not they will fit the -8 or how to drill out the hole??

Thanks for the help...

I purchased my wing kit from someone else and it had the standard fuel caps. I have very little real world experience with them beyond them being very cumbersome to open. I have read about and have seen that the standard caps are prone to leaking.

Those two factors together prompted me to order new caps. I didn't want Locking(or I would have gone with the newtons) and the T-00007's are much easier to open than the standard. While not part of my decision they are much lighter as well.