Rivets

With a good rivet gun you can trigger it for one hit. Check the hit, change angle and hit it again. You don't want to miss...... especially if it is an aircraft wing! These rivet guns can really hit hard...

snip

depending on what type of rivet you want to use, a squeezer may be more appropriate - see the example on my web site of riveting a hood hinge onto an older car - go to

click hobbies/cars, and next to the 36 cad, choose the link for hood restoration and you can see a small squeezer in action - it worked great.

You might look into spinning rivets, such as is done to splice chain saw chains. There are simple bench tools and drill press accessories with two concave-rimmed bearings that roll the shank into a smooth round head. I didn't find a picture, but I ran one in a factory.

I used to file nail heads smooth in a drill press, cut them to length and set them with a ball pein hammer.

jsw

I will definitely get a squeezer if I see one in an auction/garage sale. Not sure I want to pay $170+ until I am convinced they do well with *solid* rivets (I note you were using tubular).

Michael Koblic, Campbell River, BC

1) I tried to look up spinning rivets. It seems that it is a technique similar to but not identical to orbital riveting. I found more on the latter. It looks like a useful technique. One would have thought that an orbital attachment should be easy to make for a drill press. However, I found one description for a *spinning* tool and will have a look into it further. It seems also easy to make. 2) I have done the hammer method but not all the pieces are suitable for it. Thus the air gun and bucking bar option interest. Or a squeezer. 3) I tried improvising rivets from a welding rod but it seems too hard

- the tails split. The rivets I got now seem much softer.

Michael Koblic, Campbell River, BC

Greetings Michael, I have done enough riveting with steel, copper alloy, and aluminum alloy rivets to be able to offer a little advice regarding riveting and air guns. Once you learn how to use one they save lots of time but it takes a while to get the hang of using one. For small rivets even a cheap chinese air hammer will pound too fast and hard at full throttle. So a light touch on the trigger or using a throttling valve before the gun works well. I like the valve before the gun. Then the riveting is consistent. You can't be shy though about setting the rivet. Too many light hits will harden the rivet before it is properly set and the rivet head will start to crack. So practice on the rivets you are going to use on some scrap first. It's easy to make special rivet sets for making the rivet heads decorative heads if that's what you want. You can use a Dremel tool to carve out a cavity in a steel set and then case harden it or just use drill rod and harden and temper it. The holes for the rivets should be close to the rivet diameter. If the hole is too big the rivet shank will try to expand to fill the hole but won't be able to and will bend instead. This bent shank inside the hole will loosen much more easily than a shank that fills the hole completely and tight. So it's best if the rivet grips the part not just by the heads but also by swelling into the part. Pounding on the rivet heads too hard or long can also cause the metal under the head, the piece being riveted, to expand outward as it is compressed by the hammer blows. This can cause the metal to pull away from the metal below it a little distance away from the rivet. So then you end up with two pieces riveted together that only touch in the area immediately around the rivet and are a few thousandts of an inch apart in the areas between the rivets. Hope this helps. Eric

I have used a regular HF air hammer, like is used for muffler cutting and such, the shanks are the same size. All you need to do is change the regular tooling out for the rivet set. You need a backing/bucking bar to support the head when doing this, these come in different sizes and shapes. Not a big task to make a special one, either. Check the aircraft building suppliers for both the set and the bucking bars, Aircraft Spruce is one place. Squeezers support the head and round over the rivet end, so need two parts to do the job, taking the place of set and bucking bar. If you want to use a hydraulic press, you need a set and a backer.

Stan

[...]

Thanks. Your advice definitely agrees with such experience as I have been able to gather so far. I have a box full of small scraps which have by now been riveted together :-) I am especially gratified that you confirm the need for the rivet holes to be snug: I found that for instance the usually prescribed #30 hole for 1/8" rivets was too big.

That last bit is something I have not seen mentioned anywhere else. Another proof if one needed one how useful this group is!

Michael Koblic, Campbell River, BC

[...]

That is encouraging. Eric makes a valid point about the trigger control but there is a great economic incentive to learn to use a regular air hammer particularly as the reason to use it is not the volume of riveting but the site of the rivets which would make it difficult to use the usual ball peen hammer method.

I am not sure if I missed something but I thought bucking bar is just a big chunk of steel which is flat at the business end and shaped in such a way that it can be held comfortably in place.

I was not really thinking about a hydraulic press but an arbor press as shown in the link. I assume based on the info gathered so far that a 1/2 ton press should be sufficient.

Michael Koblic, Campbell River, BC

Bit of digression

I got a regulator - female air-connector, short hose, regulator, another short hose, male air-connector (rule - make a portable air fitting so it can plug back into itself when not in use - keep it sealed so can carry it loose no probs). So wherever you can plug in a tool, you can have your own regulator. Good for very controlled air-powered angle-grinder - especially when working off someone else's shop air supply with pressure going up-and-down.

Wondered about throttling valve too. Would have different effect? Would limit "free" speed of tool while approaching full power as the speed fell under load?

What throttling valve do you use?

Richard S

I just use a valve similar to a ball valve. It is just before the air hammer. If using a throtlling valve in the line far from the tool then a regulator is the best way to go because it keeps the pressure constant. With just a valve the pressure downstream of the valve will rise to the pressure upstream of the valve when no air is being consumed by the tool. When the trigger is depressed the tool will run at high speed briefly and then slow down as the pressure drops. This high speed could cause the hammer to strike the rivet too hard a few times. Eric

Yes, there still useful info here. The signal/noise has gone way down, but the signal is still there. Bob

For what size rivets?

I have a HF 1/2 ton press and I don't think it would be up to the task myself (but haven't tried either). See:

Maybe for something small like 1/8 inch and maybe aluminum rivets it would be okay. It does a pretty nice job of cracking black walnuts and pressing small pins in/out of stuff. Works good for crimping on flat ribbon cable connectors too...

I've used a ball peen hammer though and for steel rivets around

1/4-5/16 inch diameter it has take numerous hits with a solid steel bench backing them up...

You might be able to apply pressure with the arbor press though and then whack the toothed bar/ram a couple times on top simultaneously. You should make some sort of cap for the top of the ram first so as not to damage it though.

If I had to do it over again I would get the 1 ton press. But I still have my doubts over how well it would form/crimp rivets of much size...

[ ... ]

That would describe one used for setting flat-head (countersunk) rivets. However, for round-head, cone head, or other shapes, there needs to be a corresponding cavity, so the head is not distorted by the blows from the other end.

Depends on the size of rivet you are trying to set, and how many you plan to set. A bigger arbor press makes it easier to get the needed forces, so you can keep working longer before you get tired.

BTW With aluminum rivets -- they harden over time, so if you get a batch of old rivets, take time to anneal them first. (Just heat them up to the right point, and then let them cool.)

This site:

give useful information about this -- with the only problem that I see (with my OS and browser) is that in the tables the degrees sign shows up as a curly-armed 'Y' instead. Just read around that. :-) Based on this, it is important to quench them in water below 30 degrees C.

Enjoy, DoN.

That is not the way I understand it. The air gun has the set with the shape of the rivet head and the force is applied to the rivet head, not the tail. Most of the bucking bars I have seen are applied to the tail and are flat. OTOH I have had some difficulty with the concept of hitting the head of the rivet rather than the tail which you want to form. One would have thought that the material being riveted, if sufficiently thick, will absorb the power of the air gun. Clearly that is not the case.

The only rivets I have now are 1/8" round head solid rivets. The commonly available squeezers have 14" handles and are said to handle up to 1/8" steel rivets. I somehow doubt that they develop more than

1/2 ton, I would have thought considerably less.

Based on that info I shall avoid aluminum rivets :-)

I spent this PM fiddling with rivet spinning. I found some info on the 'net. I tried three tools: One with simple depression roughly shaped like the rivet head (the guy who posted this detailed procedure showed some nice results). It did not work for me. I suspect the original author used much more pressure making it almost a squeeze press. The second one was a v-groove across the face of the tool. It worked sort of, I suspect the groove needs to be shallower. Anyway, it was better than the first method. I also ground a face of a rod to 6 degrees angle (an angle apparently used by the orbital riveters) and tried it in a drill press. That one gave the best results but I am not sure what it did to the drill press bearings.

All of these methods were OK at starting the riveting process but very poor at finishing it (I should say I used copper rivets to experiment). More to the point I suspect that they hardened the copper and when I tried to finish the riveting by hammer it split the rivet tail like a star.

The best results are still using a home made set to start the rivet tail and finish with a hammer.

Michael Koblic, Campbell River, BC

The driving is normally done at the free end, not the headed end, and normally the tooling is shaped to produce a form similar to the head when the job is done. The amount of stick-out is critical to get proper behavior with the air gun. If the head is countersunk flat, then the bucking bar is flat. And often the free end is being upset into a similar countersunk hole -- depending on lots of things, so the shape of the set in the gun will be selected appropriately.

The 14" handles are longer than the handle on a 1/2 Ton arbor press. And depending on where the pivots are located, the lever amplification may be significantly greater as well. (Measure from the center of the pinion to the pitch height of the rack tooth and compare that to the maximum distance from the center of the pinion to the end of the sliding lever.)

The 1/2 Ton press works well on copper alloy based electrical terminals. I used to have such a tool at work built around the small arbor press. But those terminal might as well be considered tubular rivets, and some certainly are.

I really have my doubts about the 1/2 Ton press with even 1/8" steel solid rivets. *Maybe* with freshly annealed aluminum ones.

Why? They are better if what you are riveting is aluminum. And they take less force than steel rivets -- even when age hardened. Just plan to shake a few (a few more than you expect to need) in the path of a high temperature heating blower (e.g. 900 F Master Specialties paint stripping/heat-shrink-sleeving gun), dunk in water, and set in the next half hour. The critical stuff is if you are using the rivets in safety-critical tasks such is making an aircraft. Aren't you using them for the sundials? Just experiment. :-)

How noisy was it?

Too much metal protruding from the workpiece, and too much working resulting in work hardening.

But if the rivet tail is where it can be observed, and is important to your product's appearance, you want a shaped rivet set, and another one on the bucking bar to match the head. (Squeezers have properly shaped parts on both sides -- selected to be appropriate to the head of the rivet being set.

Good Luck, DoN.

Most rivets, at least the ones used on airplanes, are driven from the head. the bucking bar goes on the other end.

-- Cheers,

John B.

Sorry. Solid aluminum rivets used on airplanes are driven from the head end and bucked with a flat ended bucking bar. The rivet set, in the gun, does have a cavity to fit the head shape of the rivet.

See :

more rivet sets then most people care to see. The sets for flat heads are on page 7.

-- Cheers,

John B.

The tool I used had two hardened rollers on the end, on a horizontal shaft, with the desired heading shape ground into them. It headed steel rivets in Nylon straps which wouldn't resist any sideways force from an orbital tool and the rivets might buckle if hammered or squeezed. The balanced pressure between the two rollers kept the rivet centered.

I couldn't see what type of bearings the rollers had. I didn't have to oil them so they might have been angular-contact ball bearings. The rollers looked like they could have been made from the inner races of angular contact bearings, ground back to the center line to leave a half-round rivet head shape between them:

were perhaps 1/4" - 3/8" diameter.

Heading a rivet didn't require a lot of force on the drill press handle.

jsw