rivets, caps, washers and acorn nuts

[beardrum]

There is another current thread about this, which I didn't want to hijack, but I have a (another) question.

Is process correct? To mount something on the inside of an exterior wall (thru the skin of the trailer), I would first drill a hole, insert the fat end of the rivet into the hole and thru whatever I'm mounting on the inside. Then thread a washer, cup side UP, onto the stem of the rivet, put the gun over the skinny end, and crank away until it breaks off, then snap a white cap over the washer, maybe with a bit of goopypuck to help seal and hold it on.

Is that basically the process?

Are the acorn nuts threaded onto the rivet stumps inside, or are they on bolts, with the outside heads covered in the same manner as rivets.

Thanks, I've not done this before.

-c

[jwcolby54]

I found a nut on the floor inside of my Scamp, and eventually found a threaded "bolt" missing the nut. So the answer in part is that wherever you see one of those nuts on the inside, there is a threaded bolt coming through from the outside. For example hanging all of the cabinets.

OTOH for example, the water heater panel on the outside is pop riveted in place with 20 rivets around the perimeter (on mine). I am repairing mine this week and just drilled out the "head" of those rivets in order to allow me to pull that entire unit out to the outside of the Scamp.

I don't know about "threading the rivet" but I don't think that is how it works.

[beardrum]

Acorn nuts jammed on the rivet heads didn't make sense to me either, but that seems to be the case for at least some of them. Either that or the bolts are totally stripped, so that the nuts just spin. I dunno.

-c

[Brian B-P]

I believe that in both Bolers and Scamps those acorn nuts are used only as decorative caps on the inside tail (not the head) of rivets; bolts were not used through the shell. Rivets don't have threads, but after a rivet is expanded into a nut, if the nut later falls off there will be threads pressed into it.

[Steve L.]

Assuimg you're using a cap on the outside, put plastic washer (that the cap snaps over) on the rivet, push rivet in hole from outside through as many layers of fiberglass as appropriate place acorn nut (if used, or an aluminum washer) firmly over the rivet end and set the rivet.

The aluminum washer (available at most places you buy rivets in hole sizes that match the rivet OD) makes for an unfinished appearance but is helpful when riveting softer (softer than steel) materials. The expanding end of the rivet can crush fiberglass and the washer serves to spread the load and compress the sandwich. There are rivets made for softer material but they are really ugly once they spread and are best used where the inside is hidden.

[beardrum]

A picture is worth a thousand words; thanks so much! The geometry appears to be what I had deduced from what I can see on my Scamp, except for the part about expanding the rivet into the acorn.

On the rivet/washer/cap sets I got from Scamp, the shank of the rivet (as opposed to the pin) is about an inch and a quarter long, and all that material is what would get expanded into the drilled hole and the acorn nut, and that seems like a lot of stuff. It also seems as if keeping the acorn tight to the inside surface might be challenging. Maybe once it's started, a turn or two on the nut will tighten it down.

Good tip about a washer under the rivet head to help distribute the compression of the rivet head across a larger area! It would just my luck to pull a bunch of quarter inch (plus) holes right through the skin of the trailer!

You guys are great, and I appreciate the chance to talk through some of this stuff!

Chuck

[Steve L.]

Not to quibble, but the washer doesn't go under the rivet head but on the part of the rivet exposed inside. Instead of the acorn nut (NOT both). You'd be making a sandwich where the rivet head is one slice of the bread and the washer is the other slice and the fiberglass layers are the crunchy middle stuff(!)

[Steve L.]

In a sense, as the bulb at the end of the pin is drawn backwards into the rivet proper, expanding the rivet, the bulge “herds” the washer along to tighten the joint. Replace it with an acorn nut and the relatively soft rivet bulge just embeds into the nut threads. Twisting the acorn nut after setting the rivet will just cause the nut to fall off your new joint.

When I say "herds" I mean just a little. You should have the washer pretty much tight against the wall and the bulge moves the washer only a little bit tightening the joint a little bit.

[beardrum]

Steve, I think I got it: rivet collar or whatever outside, washer inside, OR expanding part of rivet expands into acorn nut on the inside . The acorn nut part of all this is what seems insecure.

Thanks again
c

[jwcolby54]

So the nut that fell off needs to have the rivet replaced? I screwed it back on but the rivet turns now, i.e. once I tighten the nut at some point it just starts spinning.

[stevebaz]

One thing to watch for when using the acorn nut is that the rivet isnt too long once its inside the nut. Put the rivet through the material to be riveted and put on the acorn nut. Before setting the rivet check that the acorn nut will go up to the surface your pulling together without pushing the rivet back outside. If the acorn nut sits away from the surface more than just a hair when you set the rivet it will lock the nut in place but wont pull the assembly up tight. Scamp sells alot of rivets way too long so you need to check and use the right length rivet when using the acorn nuts.

[Carol H]

Originally Posted by beardrum

On the rivet/washer/cap sets I got from Scamp, the shank of the rivet (as opposed to the pin) is about an inch and a quarter long, and all that material is what would get expanded into the drilled hole and the acorn nut, and that seems like a lot of stuff. It also seems as if keeping the acorn tight to the inside surface might be challenging.

Chuck

Chuck as been said Scamp sells a lot of different sized rivets. One size does not do all. What length rivet you use depends on the total thickness of what you are attaching together.

I have found its works best when replacing rivets and acorns if you have someone hold the acorn nut firm to the wall on the inside while you put the rivet with the plastic ring holder on it through the hole to make sure it is the correct length - you will be able to see while standing on the outside of the trailer if the rivet is to long. Once you have the right length rivet have someone hold the nut in place firmly (using a pair of pliers works well) over the rivet head on the inside wall when you shoot the rivet.

[jwcolby54]

So the acorn is really a "pretty"? It seems like they will come off more easily than a flat washer.

[Carol H]

Yes the acorn is a Pretty, but it will not come off any easier than a rivet with a washer on the inside if the right length rivet has been used. Both will need to be drilled off.

[jwcolby54]

Well the reason I asked is that I found a nut on the floor. Found the rivet and screwed the acorn back on but it didn't tighten down really. It seems that threads formed by popping the rivet are going to be soft and less robust that a honkin flat washer under the expanded part.

When it is an overhead cabinet held on by a 4 of these things that seems pretty light weight. I was intending on hanging my 14 lb 32" tv from the cabinet over the bed but now I have my doubts.

[Carol H]

Originally Posted by jwcolby54

Well the reason I asked is that I found a nut on the floor. Found the rivet and screwed the acorn back on but it didn't tighten down really. It seems that threads formed by popping the rivet are going to be soft and less robust that a honkin flat washer under the expanded part.

When it is an overhead cabinet held on by a 4 of these things that seems pretty light weight. I was intending on hanging my 14 lb 32" tv from the cabinet over the bed but now I have my doubts.

First off the rivets are rivets they do not screw into the nuts so once they break off the rivet they can not be screwed back on.

The rivets will from time to time break off from acorn nuts due to the fatigue of the trailer flexing. I have over 6 years had a few of them go on my older trailer mostly after many miles of travel over rough roads. The reason people use rivets rather than stronger screws is for this reason - better the rivet snaps than the fiberglass crack.

The overhead bins are not designed to hold heavy items although I do have a 19" flat screen mounted on my rear overhead but I do not travel with the TV mounted on the overhead. Take it down and put it under the covers of the bed.

[jwcolby54]

Originally Posted by Carol H

... although I do have a 19" flat screen mounted on my rear overhead but I do not travel with the TV mounted on the overhead.

How did you mount that? I am not finding mounts that hang from above, rather they all seem to mount to the wall behind the tv. I am about to do something really ugly and crude.

[Brian B-P]

Originally Posted by beardrum

The acorn nut part of all this is what seems insecure.

I'm sure it is, since nothing about the nut or rivet is designed to work this way, but it doesn't matter much since the nut has no structural purpose.

Originally Posted by jwcolby54

So the nut that fell off needs to have the rivet replaced? I screwed it back on but the rivet turns now, i.e. once I tighten the nut at some point it just starts spinning.

I wouldn't even momentarily consider replacing a rivet just because the nut fell off. Glue the nut on if you would like...

Originally Posted by jwcolby54

So the acorn is really a "pretty"? It seems like they will come off more easily than a flat washer.

Yes, the acorn nut is just ornamental. A washer is very functional, as Steve explained... and it will not come off without destroying the rivet.

[jwcolby54]

Brian,

somewhere in this discussion was a reference to using a washer to "spread the load" on the back side of the rivet. You seem to indicate that the acorn is truly decorative, so what replaces the washer in "spreading the load". It seems that you could have both, a washer and then on top of that the acorn.

However the acorn appears to actually prevent the rivet from spreading out as it normally would, and thus having even less surface area holding the back side in place.

Or perhaps I am not visualizing the process correctly.

[Brian B-P]

Originally Posted by Carol H

The rivets will from time to time break off from acorn nuts due to the fatigue of the trailer flexing. I have over 6 years had a few of them go on my older trailer mostly after many miles of travel over rough roads.

Rivets sometimes break as Carol has explained, but it is unrelated to the nuts. If the nut falls off but the rivet is intact, that's an ornamental issue; if the rivet breaks, that's a structural issue.

Originally Posted by Carol H

The reason people use rivets rather than stronger screws is for this reason - better the rivet snaps than the fiberglass crack.

I disagree. I believe that the rivets are used simply because they are cheap and fast (thus cheap to install), and perhaps because they don't loosen (much) over time.

I have heard this theory of using rivets as a deliberate weak link. Again, I disagree - I think it's just poor design and construction. Are there any parts of your car that fall apart on rough roads to protect the parts they're in from cracking? Even in a fiberglass car? This has been a contentious issue in the past, so that's as far as I'll take that subject.