keeping parts snug during riveting

[prestwich]

I'm having varied luck keeping things snug when I rivet them. Seems like they cleco up nice and snug, nested dimples, etc., but when I start riveting, a gap magically appears.

I wasn't overly concerned about this when I was putting the HS skeleton together and riveting the skin to the forward spar and the center ribs. Now I'm on the last step, which is to rivet the rear spar assembly (-7) to the skin, and along one row I've got a gap of close to 0.020".

Another row is no more than 0.010", but it's still more of a gap than I'd like. I've managed to put in a few rivets on the other side and keep things snug by clamping the skin to the spar as close to the hole as I can. Adjacent clecos are way too far away to keep the parts tight, and once one rivet gets a gap, it propagates forever.

It almost seems like the rivet forces the parts apart as it's set. Anyone else had trouble with this, or am I just the idiot of the day today?

[TomNativeNewYorker]

Wingnut and stubby clecos seem to pull metal together tighter. You really can get things tighter if you use a wing cleco and use a washer on the backside.

Clecos an inch apart should be sufficent to hold it all together.

[aparchment]

Use cleco clamps (like c clamps only spring loaded) on either side of the rivet you are installing, and leave enough space for the squeezer head or the rivet gun and bucking bar.

Are you sure your dimples are nesting correctly?

Antony

[bmurrish]

It almost seems like the rivet forces the parts apart as it's set.

Are you sure it's pulling apart or is the material bending? You may see this if the shop head is on the thinner material side, especially on rib flanges.

[dpansier]

If you are using a squeezer this works well.
Cut a 1/4" long pc of small dia. polyflow tubing and place it on the shop end of the rivet. The squeezer will make contact with the tubing forcing the sheets tight before the die forms the shop end of the rivet.

[RAgbunag]

I've been using small patches of scotchbrite with holes in them to force parts together prior to riveting, with limtied success.

I've heard of using sections of tubing over the shop ends of the rivets, and think that it would work better. Can anyone tell me specifically what tubing they used, what diameter worked best, and where they got this stuff?

As always, thanks.

Rudy -9A
Ripon, CA
starting ailerons

[prestwich]

Thanks for all the replies. Wing nut clecos, hmm, never heard of them before. Might have to pick up a few to give them a try. The cleco clamps close to the target rivet do seem to help. Wish the squeezer didn't take up so much more room than just the diameter of the sets.

The tubing sounds like a clever idea, and I'd like further info on that, also. Not sure what "polyflow" is.

Bill, no, not bending, definitely pulling apart. Van's says this is fairly typical and not a concern, so I'm not going to rework what I have, but sure want things to look better in the future. I guess the HS is going to be the ugliest part of every RV!

[TomNativeNewYorker]

Thanks for all the replies. Wing nut clecos, hmm, never heard of them before. Might have to pick up a few to give them a try.

[TomNativeNewYorker]

The stubby ones seem to pull a little tighter as well

[dpansier]

I started out using a rubber facet washer on the shop side of the rivet, squeezing it held the sheets together but made black marks on the finished parts. The rubber is a little too hard and the appearance was not to my liking.
The tubing I'm using is 1/4' OD, 1/8” ID plastic. This type of tubing is used to supply air to pneumatic devices widely used in industrial machines.
I cut it with a razor blade, make sure the ends are cut square or you will difficulty keeping the tube under the squeezing die.
I have seen similar tubing at Home Depot and Lowes, it is a stiffer tube sometimes used to run water to ice machines in the home refrigerator.
The stiffer tube will squeeze about 20 to 25 rivets before it deforms, I recently tried a more flexible tube of the same size and found I got much more life then the stiffer tube.
A five foot length will last a lifetime of aircraft building

[Snap]

My turn CJ

[prestwich]

The tubing I'm using is 1/4' OD

Wow, that's some big tubing! Seriously, thanks for the tip; I'm gonna give it a try.

[N200PF]

If you are using a squeezer this works well.
Cut a 1/4" long pc of small dia. polyflow tubing and place it on the shop end of the rivet. The squeezer will make contact with the tubing forcing the sheets tight before the die forms the shop end of the rivet.

Can anyone post a picture of what this looks like going together!?! I am having a tough time getting my mind around this one but it sounds like it works!

THANKS!

- Peter

PS - Snap I'm still waiting for my chance to use the SUPER COOL Emoticon!

[dpansier]

Peter
I have photos using the tubing but not sure how to post them to this forum. I can email them to you if you like and you can post them.
Don

[captain_john]

Don,

If you need for me to post a pic, shoot me a PM and I will give you my email addy and I will post them for ya!

CJ

[prestwich]

While we're waiting on pics, think of a small, stiff compression spring that would fit loosely around the unformed shop head of a rivet ready to be set. The spring is longer than the unformed rivet, but when fully compressed is shorter than the formed rivet.

So the squeezer contacts the spring before it contacts the rivet. As the spring compresses, because it's so stiff, it forces the skin and spar (or whatever) together and holds them that way.

Squeezer continues its travel and contacts and forms the shop head of the rivet, still maintaining spring pressure against the parts.

Substitute the tubing for the spring. This really is a great idea!

[captain_john]

Pics are up!





CJ

[N200PF]

AH HA!!!

GREAT IDEA!!! I'll be using that one FOR SURE!!!

Is 1/4 OD what you're all using?

- Peter