drill size?

[Stormy Weather]

What drill size do I use to drill out rivets on the underbelly?

[markdoane]

Just use the same size as the pop rivet. Usually 1/8", unless they have been replaced with larger rivets by a previous owner.

[Inland RV Center, In]

There are three correct drill sizes for Airstream work.

# 30 for 1/8" pop rivets and the buck rivets

# 21 for installing Olympic rivets.

# 11 for installing 3/16 rivets.

Common machine shop practice says a 1/8" rivet will not fit in a 1/8" drilled hole. Doesn't matter what speed the drill bit turns at, or even if you used a drill press.

The drilled hole, when measured very carefully, will be ever so slightly triangular shaped, which is caused by the fluting or spiralling of the drill bits themselves.

Numbered drill bits sometimes are hard to find.

We were asked, a long time ago, to have those drills available as a kit, which we did.

Andy

Andy

[markdoane]

Andy,

The question was what drill to use to 'drill out' pop rivets. I agree with your coments on what drill size to use for putting in bucked rivets, but pop rivets are slightly undersized and a 1/8" drill is the proper drill for standard, hardware store, pop rivets.

[Over59]

http://shop.store.yahoo.com/toolsplu...-numbers-.html

[wahoonc]

Originally Posted by markdoane

Andy,

The question was what drill to use to 'drill out' pop rivets. I agree with your coments on what drill size to use for putting in bucked rivets, but pop rivets are slightly undersized and a 1/8" drill is the proper drill for standard, hardware store, pop rivets.

FWIW
We use oversized bits 9/64" for drilling holes in aluminum for 1/8" aluminum rivets. As Andy says the hole isn't perfectly round. If you drill the hole with an 1/8" bit you will have trouble getting the rivet in the hole. As far as drilling out if the rivets on the belly pan are anything like mine were you will end up having to cut them out. Most of mine still had shanks hanging out of them. I suspect a PO because most of them were steel not aluminum.

Aaron

[markdoane]

I'm just relating what I heard:

Hole size can be important in blind riveting. Too small a hole will, of course, make rivet insertion difficult. Too large a hole will reduce the shear and tensile strengths and it may even cause bulging or separation of the members by allowing the rivet to expand between them instead of on the blind side. Best practice is to follow the hole size recommendations provided. Also, avoid burrs in and around the holes.
- from http://www.emhart.com/products/pop/popex/factors.htm

I haven't had any problems fitting 1/8" pop rivets in 1/8" holes. On the other hand, I don't think using a 9/64" is a problem.

[Ken J]

I assume that you use a #21 for the 5/16 buck rivets??

Ken

[markdoane]

Originally Posted by Ken J

I assume that you use a #21 for the 5/16 buck rivets??

Ken

Yeah, but I drill them first with either a #30 or 1/8", then ream them with the #21 using a pneumatic drill at high speed, followed by de-burring. Makes a really nice hole.

rivet size? I assume you meant 5/32".

[Ken J]

Thats what I thought - thanks!

[Inland RV Center, In]

wahoonc

Dimensionally 1/8 " equals .125

# 30 equals .1285

9/64 equals .140625, which is "way" to large for a correct fit for a 1/8" pop rivet or a 1/8" buck rivet.

Excellent way to beg for water leaks, and, poor structural strength.

If it's worth doing, do it right. If it's not, then leave it alone.

Why is it we don't, sometimes, have the time to do it right, but manage to find time, when it's necessary to do it over again, because it wasn't done right, the first time?

Using the right tool, for the right job, always pays dividends, even drill bit sizes.

Wrong kind of job security........

Andy

[markdoane]

Originally Posted by Inland RV Center, In

wahoonc

Using the right tool, for the right job, always pays dividends, even drill bit sizes.

Wrong kind of job security........

Andy

I succumb. The max hole size for a 1/8" pop rivet is .131", so either a 1/8" or a #30 will work. 9/64" is way oversize.

We're still talking about belly pan pop rivets, aren't we?

[Inland RV Center, In]

markdoane.

We have a 1997 Excella trailer in our shop, that is a good example of wrong tools.

The new owner was not aware that the previous owner had a severe collision damaging the front and left rear.

The current owner has mostly gutted the trailer so he can create his own design. In the process of removing the foam backed vinyl wall covering, he discovered considerable staining from water on some of the sheetmetal.

The causes, as we found them, was both the square and rectangular sky lights were cracked and leaking water. Unfortunately, the water came out on the floor and therefore was not initially noticed.

Secondly, the front window and both wrap windows were replaced along with one front segment, using olympic rivets.

Amazingly, we found that who ever did the work, used a 3/16 inch drill bit for all of those rivets, and did not use any tape or sealers. After completion, a small amount of Parbond was used on top of the windows "only".

Leaks?? Only a couple of hundred of them.

The fix? Drilling all new holes and covering the 3/16 holes with sealer.

Nice looking? Hardly, but the new owner cannot afford replacements.

The moral of this little story?

Use the right "tools".

Pays many dividends.

Andy

[wahoonc]

Originally Posted by Inland RV Center, In

wahoonc

Dimensionally 1/8 " equals .125

# 30 equals .1285

9/64 equals .140625, which is "way" to large for a correct fit for a 1/8" pop rivet or a 1/8" buck rivet.

Excellent way to beg for water leaks, and, poor structural strength.

If it's worth doing, do it right. If it's not, then leave it alone.

Why is it we don't, sometimes, have the time to do it right, but manage to find time, when it's necessary to do it over again, because it wasn't done right, the first time?

Using the right tool, for the right job, always pays dividends, even drill bit sizes.

Wrong kind of job security........

Andy

Andy,
I agree that the proper sized bit is critical especially when doing watertight or structural work. I probably should have clarified that the 9/64" bits are used on non watertight assemblies and the rivets are painted which adds a few thousandths to the equation. IMHO on the belly pan it is not as critical as somewhere else on the unit. But I do stand corrected

Aaron

[Stormy Weather]

Gentlemen, thanks for your exchange. I have learned much and Andy I'll be calling to order a couple of drill sets on Monday because I'll be needing the correct sizes for the interior work I plan on doing. Anyway, I managed to get the back end of the belly pan off last night, only to find the back 8 inches of my floor in the bath was totally rotted out. This morning I removed the black tank. Guess what I found in the bottom of the tank? A 1/8 inch hole! My new adventure continues.....

[Over59]

Well stormy that's how it starts. You broke the first rule of avoiding a shell off restoration, you looked Now that you have started to take it apart you will find it harder and harder to not look. The trailer will be great when you're done. I started to replace a soft area in the rear bath after gutting the trailer. By yesterday I had most of the floor out on the way to a shell on floor repacement. The front floor look great, like new. Problem was that the plywood was rotted out where the screws where into it through the channel. This was evident when trying to take them out and they turned but didn't come out, stripped wood. If you really what a surprise look between your belly pan and floor .

[markdoane]

Originally Posted by Stormy Weather

Guess what I found in the bottom of the tank? A 1/8 inch hole! My new adventure continues.....

That's easy. Bore it out to 0.1285" and stick a rivet in it!

[Ken J]

Thats what I found when I started removing the floor on my 58 - the floor was solid, but where the bolts and screws were, it was rotted/not holding the floor to the frame - so out went the whole floor and in with new.

Ken

[Inland RV Center, In]

wahoonc

The rivet fit for the underbelly, is indeed critical, but for a different reason.

The underbelly, because of it's thinness and lack of places to fasten it to, has a great tendency, while in motion, to flutter.

That being the case, loose fitting rivets will allow the underbelly to flutter, even more so, further artificially enlarging the holes in the metal. The underbelly also will shake when the running gear is not properly balanced.

That will result in premature failure of the rivet heads that were recently installed.

However, to fasten the underbelly, to almost a fail safe degree, use "large head 3/16 inch pop rivets." Use # 11 drill bit holes for them.

Costs a little more, but pays huge dividends.

Andy