Rivets vs threaded fasteners
 

This post is spurred by a conversation with a student yesterday. He suggested that we use rivets instead of #10-32 fasteners to attach a critical piece of structure. My first reaction was negative, but I found myself unable to articulate a truly good explanation why we should use fasteners over rivets. As an engineer, that's not acceptable, and is a sign that I've got some unjustifiable biases in my thinking.

Would anyone be willing to share their engineering based opinions about the pros and cons of using rivets vs threaded fasteners in FIRST robots? Are there certain applications where your team prefers one type over another? Do you have certain design rules, tools, specific rivet part numbers, etc. which you use successfully? Would you, for example, use rivets to attach a plate sprocket to a versahub? Why or why not?

We've used rivets sporadically in the past, but it always seems that by the end of competition season, many, if not all of them have been drilled out and replaced with threaded fasteners. Rivets are used quite successfully in the industrial world, on a wide variety of applications, so I suspect that we are just using them wrong.

Here are my observations based on past experience. Please correct my mistaken beliefs if your experience says I'm wrong:
- If parts need to be removed for servicing the robot, you should use threaded fasteners. Rivets should be used for installations which are expected to be permanent.
- Rivets are best in shear applications. If used in tension applications, they tend to loosen up over time, and aren't easily re-tightened except by drilling out and replacing the rivet.
- Rivets of similar strength to threaded fasteners (tension and shear) don't offer significant weight savings. Corollary: Replacing a threaded fastener with a lighter rivet results in reduced strength in that joint. (The exception may be if use of a rivet results in the elimination of a nut)
- Rivets are most useful and have the most potential for weight savings when joining very thin materials (ex 1/16" thick aluminum) which can't be tapped.
- When riveting soft materials, like lexan, the head of the rivet must be against the soft material, or a close fitting washer must be used on the "bulb" side, so the bulb doesn't pull into the soft material.

Anyone care to share their experiences? I'm hoping for more detailed responses than "We use rivets. They work great for us." How do you use them? What do you do to make them work for you?

Re: Rivets vs threaded fasteners
 

I like to use them in structural applications. Idea being an overall weight savings over several mostly permanent joints. Spread the load out with more fasteners, which see less stress as a result.

I agree 100% with threaded fasteners for moving parts and modular mechanism interfaces

Re: Rivets vs threaded fasteners
 

Threaded fasteners do make removal and replacement a bit easier. If you know you need to remove a part to service it (or another part) then use threaded fasteners.
Not quite true. Screws in tension have stress risers at the threads which can cause the thread to fail. Threaded fasteners tend to loosen due to vibration. Rivets tend to loosen because they are incorrectly sized (reach is wrong or hole size is wrong). Rivets only loosen in tension if there is a shock load on them. So if you expect a lot of vibration, use rivets. If you expect heavy shock loads, use threaded fasteners (with Loctite).
Most threaded fasteners are hardened steel. Most rivets are aluminum. For the same strength the rivet will typically weigh 2/3 the weight of screws.
Rivets tend to be useful on thin material for that reason as long as the reach of the rivet is correct, however, rivets also save weight when the strength of steel screws are not needed and nuts can be removed.
The same is true for screws. Soft material should always have washers to spread the load of the fastener (regardless of type).

Hope that helps.

Re: Rivets vs threaded fasteners
 

So as a general basis on my team, rivet if it is non-essential, and bolt it if it is essential. If the part your securing will see a lot of wear and tear throughout the season, bolt it. If your part will need constant replacement/isn't under tension forces, rivets work best. There are some applications where we need to use bolts, simply because we can't fit a rivet gun head where we want it. And if you do use bolts, remember to either use locknuts, or locktite on regular threaded nuts. We also bolt parts that require zero, or close to zero, lossesning throughout the season, because if the hole is not perfect for the rivet, the rivet will lossen, where ever the force.

My rule of thumb, as a "we need to rivet this", or "we need to bolt this", is "will this need to be perfectly secure the whole season?" Yes: bolt, no: rivet.

Like you said, use bolts wherever parts need to come off repeatedly.

Other than that, it's a weight and ease preference, really.

Re: Rivets vs threaded fasteners
 

Considering rivets are used on aircraft, I'm surprised at this answer.

Re: Rivets vs threaded fasteners
 

Our team is very much a threaded fasteners team, though we have occasionally used rivets in a few spots. Our robot has many tapped holes and countersunk screws used in applications where rivets couldn't really be used.

We often find ourselves removing, replacing, or repairing parts of our robot. It's true that we could drill out a rivet and replace it, but it's often quite difficult to fit a cordless drill and a riveter in a very tight spot. On the other side, there are many different styles of allen wrenches that can be used to fit in almost any spot. We have ball end allen keys, t handle, and a set of allen keys for 3/8" socket wrenches. If you have a universal joint for the socket wrench, you can really fit the allen wrench into tight spaces.

The second disadvantage of rivets is that they will only grab one wall of the box tubing. That's okay for light loads, or if you use a million of them. If you weld a few threaded inserts into your box tubing, and use a few 1/4-20's, you really cut down your assembly/disassembly time.

Our elevator assembly this year is a perfect example of quick assembly.
To disassemble it, you must remove 7 threaded fasteners.
You remove one 10-32 to release the chain and 6 1/4-20's to remove the 75" tall 1" x 2" uprights.
I don't see how this could be achieved with rivets.

Re: Rivets vs threaded fasteners
 

Out team started using threaded rivets this year. Drill the hole (or use the existing hole), insert the threaded rivet, and the part can be easily screwed on and off.

Re: Rivets vs threaded fasteners
 

Rivets are lighter and reduce slop in the structural system by filling the hole. Rivets are not easily removed.
Riveting more than 4 pieces of material together with blind pop rivets is not recommended. Other permanent type fasteners like cherry max or huck bolts would be recommended for this application.
Rivets will crush material during their installation, materials that cannot be crushed or that could be delaminated with a high point compression loading should not be riveted with traditional rivets.

Bolts are heavier and need a clearance hole to be drilled.
Bolts will not reduce slop.
Bolts are easily removed.
Bolts can be tightened to a specific torque, they will only crush material if you want to crush material.

Both bolts and rivets can withstand high tensions, compression and sheer loads if both material and size are part of the joint analysis.

Re: Rivets vs threaded fasteners
 

Since our robot this year is half made of wood, we didn't use a lot of rivets. We use a few wood screws to hold aluminum parts to wood, and some machine screws and nuts to hold other aluminum parts to wood. We have a few places where thin aluminum is attached to other thin aluminum parts, these are riveted.

We usually don't use locknuts on anything that may need to be disassembled for repair or maintenance, because it can take so long to get the screw out and back in. Instead, we depend on maintenance to keep nuts tight.

We don't use aircraft type rivets...if we did, we probably wouldn't have any trouble with riveted connections getting loose. We use mostly materials and supplies that are locally available, and that means hardware store or building supply, since there are no industrial supply places within errand distance.

When thinking of the engineering of fasteners, we usually think of the robot as a prototype, and not as a saleable commercial product.

Re: Rivets vs threaded fasteners
 

I want to counter the point that rivets are not easily removable.

Rivets are VERY easily removable. Obviously care needs to be taken to ensure you are drilling out the rivet and not the hole under the rivet.

For something that will be removed/added many times during a single competition we would opt for screws. For something that needs to be added once or twice per competition, rivets are more than acceptable. The top of our lifter this year is held on by rivets that we will drill out before we leave each competition.



-Brando

Re: Rivets vs threaded fasteners
 

Agreed, we use rivets for structures we don't expect to change but often find ourselves easily drilling them to make some changes and reattaching that structure. If we find that the subsystem needs to be removed or adjusted, we use threaded hardware as a part of the design. If we're fastening permanent structure, we look to use rivets.

Re: Rivets vs threaded fasteners
 

Using quality rivets made a big difference for us. Much as I love our local hardware store, the pop rivets they stock leave much to be desired.

Re: Rivets vs threaded fasteners
 

Threaded rivets--you mean hi-locs?

Re: Rivets vs threaded fasteners
 

Or Rivnuts

Re: Rivets vs threaded fasteners
 

The Average Joes use a lot of rivets, and our experience is that they are much faster to remove and replace, compared with nut-and-bolt fastening in the same hole size and location. We use four rivet sizes: 1/8", 5/32", 3/16", and 1/4" to replace #6, #8, #10, and 1/4" threaded fasteners, respectively.

We were inspired by a respected mentor's claim, posted here a few years ago, that he could remove a rivet faster than any challenger could remove a nut and bolt. We tried that speed test ourselves, and when we saw he was right, we reduced our threaded fastener use considerably. We have never regretted the change.

Our team forever has used nylocks and quarter 20 bolts. I tried to push rivets year but no one seemed to listen much and I was told that rivets can't be load bearing. We have about 150 bolts on our robot not even joking.

We have some cheap rivets and a couple of riveting guns around but can someone reccomend a good set from a place like grainger(has to have a ny state contract) we got our first 2 sponsorships ever this year so we have a little bit of spending money $1,100. We used about 900 of it on raw materials (aluminum square and rectangular tubing along with some 8020) but we have a few hundred for other stuff. Also stupid question does a new control system come every year in the kop.

Re: Rivets vs threaded fasteners
 

[offtopic] Nope. It used to, when we ran the IFI system--ah, the good ol' days of near-instantaneous startup and connection--but not since we made the switch to the cRIO. But you can buy the items once/year at a discount, at least that's how it's been for the last few years.[/offtopic]

Incidentally, 1197 uses a mixture--bolts for most items, rivets for light-duty stuff that will probably not be moved much, and welding for major items that we aren't planning to change.

Re: Rivets vs threaded fasteners
 

Todd....

Come see our robot at VCU and Chesapeake...(you'll like the name) We used both rivets and 1/4-20 bolts in quantity....We've found that rivets are easiest for the students to use, especially when they want to quickly prototype systems and are not worried about how exact it is. There are pro and cons to both. Where we think rivets will work well we use them there, but there are times when there is no substitute for bolts such as arms that will be under stress as an example. (we would never ever rivet down such things as a winch or pneumatic cylinder except in some very unusual situation that might call for it.) Another thing with our students at least is that we have had to try and standardize fasteners as much as possible. very basic fasteners such as one size of rivets (in the case of Versa chassis you have to) and very few bolt and nut sizes. In earlier years we used to use a given fastener depending on its use but the students had trouble remembering all the different sizes and types let alone keeping them in inventory and stored properly.

You've seen our robot from last year. The arm used to grab and intake the ball was riveted together. During finals at VCU last year it was badly damaged, but we were able to quickly drill the rivets out and fix it between matches. But...when we went to Chesapeake we added braces in the corners and bolted them in place. What i'm basically saying is...it all depends on the application. Rivets save space and weight, but can and will be ripped out. Bolts can take a lot of stress, but placement has to be planned out better.

In last years game there was a lot of defense and more robot to robot contact so using bolts where needed was more important. This years game not so much. So what your robot does and what type of game you have would go a long way in deciding which type application you need.

Re: Rivets vs threaded fasteners
 

Does that include cleanup? And did one, both, or neither of the two removers use a power tool?


We use far more threaded fasteners than rivets; the main time we use rivets is when we don't have enough room for the nut and the material is too thin to effectively tap and get the tension we need. As noted above, rivets can't be passed them through both thicknesses of channel or tubing to get resistance to torque. When it comes down to it, we don't even use many threaded fasteners that are short enough to be effectively replaced by a rivet, and many of those go in blind so that we couldn't get a rivet in or out anyway. And we still haven't figured out how to effectively re-use a rivet.

Agree with MrForbes that if we went into production making dozens of our robot, we would design for more rivets (and welds), and fewer threaded fasteners.

Re: Rivets vs threaded fasteners
 

We standardized almost entirely to rivnuts (or hi-locks or clinch nuts or whatever they're being called these days) and 10-32 bolts, with an emphasis on lighter weight, ease of maintenance, and minimization of swarf when changing out parts.

For things that shouldn't ever need changing (radio mount, license plate holder, etc) we used standard rivets.

We're pretty happy with the results thus far.

Re: Rivets vs threaded fasteners
 

Our team has primarily used threaded fasteners over the years. In our years of "design as you go" it required a lot of assembly and dis-assembly during the build process which didn't lend itself well to rivets. While rivets are easy to remove once you have electronics on the robot having a lot of metal chips flying around isn't ideal.

This year we made a bigger move to rivets and ordered 4000 which we've used well over half of them. Compared to last year we used less than 50 on the robot.

We do like to use bolts to keep our systems modular. While it is faster to drill out a rivet with a good drill bit it is a little messier and overtime if you accidentally drill out the hole too much you don't get a nice tight fit. You can still have a modular system with rivets it depends on user preference. For us we'd rather take off key assemblies with a wrench and allen keys.

With this being the first year we used rivets heavily I would advise you keep an eye on making sure the holes don't get drilled too big. When some of the kids catch on that you need to drill out a 3/16" hole a little more to get a rivet in which requires a .19" hole they start going a little more aggressive on opening the hole up which weakens the fit since the rivets have more play. We ordered some extra numbered drill bits which worked well for drilling out rivet holes so we can get the hole size we want without someone trying to expand the hole with a 3/16" bit.

Re: Rivets vs threaded fasteners
 

I'm guessing power drill and hand rivet tool, and probably ratchet and hand wrench for the threaded. But a power tool for the threaded will probably only get things down to even, so rivets still win on weight.Teams that design primarily with gusseting+riveting in mind would probably tell you that you're designing your joint wrong if you have to run a fastener through both walls of the tube.Okay, so this has me the most confused. We exclusively use blind rivets on our robot. It's right there in the name that they're meant for blind holes. They're just about the only way to attach something in the middle of a tube, short of drilling+tapping or bolting through the whole tube. Are you talking about blind holes into solid material? That's the only kind of blind hole I can think of that (most) blind rivets won't work in.

Anyways, we move to using lots of rivets on our robots. As others have mentions, we're only using threaded fasteners for things we're planning on removing occasionally and joints that are too awkward for a riveted solution.

We're pretty standardized on all aluminum 5/32" (thanks to Vex) and 3/16" structural rivets. When we're not using the premade Vex gusset plates, we typically use 1/16" for gussets on lightly loaded joints and 3/32" for heavier loaded joints. We've mostly been reserving the 3/16" rivets for the heavy duty joints. I'm afraid we're not super-scientific on the spacing and amount of rivets. The students and other mentors tend to throw a lot of rivets at a joint because they're light and easy to install.

The only time I see problems with riveted joints that I wouldn't with threaded fasteners is when there's poor fit up. Threaded fasteners will obviously let you pull together two sides of a joint that aren't already clamped together. Rivets (especially standard pop rivets) aren't nearly so good at pulling together two sides of a joint. If you have poor fit up, you'll see gaps between your gusset plate and the tube you're riveting to. That gives rooms for thing to shift and loosen and almost always results in wobbly joints after a short while.

We use rivets because they're typically lighter and faster than threaded fasteners. Yes, a threaded fastener of exactly the right length into a threaded hole is about the same weight. It's just a lot more tedious. Installing a rivet is as fast as drilling a hole (in place if necessary) and popping in a rivet. Your other options are drilling a hole, lining up a nut and bolt on either side, then tightening. Or drilling two different size holes, tapping one, and tightening down the bolt.

Other rivet advantages are they can't be cross-threaded and it's stupidly easy to add a few more to a joint if you need to for some reason.

If you're worried about getting the right hole sizes, holes wobbling out, strength, picking the right grip range, etc. then go with the 3/16" high grip range structual rivets. Also, no matter what rivets you need, buy them from Rivets Online. They're cheaper than McMaster for pretty much all your riveting needs.

Re: Rivets vs threaded fasteners
 

This is starting to sound like a what is the best oil for your car debate. :]

We have gone from all bolts to a mix bolts & rivets. Since we switched to rectangular tube for out chassis, it is almost completely riveted. As Kevin mentions it avoids a difficult to design bolted joint in the tube.

While rivets might when a disassemble - assemble race under controlled circumstances, I think the general case goes to bolts. For an example try talking a formula one team into riveting their wheels on. :ahh:

For less than ideal fit up & tension applications, the superior clamping force of a bolt gives it the advatage. For pure shear applications, a properly done rivet design is hard to beat. Every rivet has a recommended hole size. Google is your friend.

Re: Rivets vs threaded fasteners
 

We have used rivets in the past, but I don't really like them for four (engineering) reasons:

-There is a reliance on the human factor to install them, which requires training. They can't be 're-set' like a riv-nut can be.
-Holes cannot be opened up as much to allow for mis-alignments or tolerance stack-up when using rivets.
-They are (as pointed out) sometimes tricky to use with soft materials or materials susceptible to creep.
- Drilling rivets out takes a power tool, a drill bit, and can introduce metal swarf into a robot. Not an ideal situation for several reasons.

Rivets can, and are, used quite successfully in FRC. I prefer the advantages of threaded fasteners and blind threads to those of rivets though.

We use PEM (cinch) nuts and Riv-Nuts frequently on our robot. We love blind fasteners because assembly is faster than a fastener+nut and we can put mounting points in locations traditionally unavailable to faster+nut combos. We can put blind threads into thin material and thick materials with ease. Everything can be quickly disassembled. And, unlike tapping material directly, damaged threads can easily and quickly be replaced. At least as quickly as rivets.

Also, I would posit that I could uninstall and then install a blind-threaded fastener faster than a rivet of similar strength could be removed and installed. Cordless impact drivers are *awesome*.

Re: Rivets vs threaded fasteners
 

We switched almost exclusively to rivets many years ago, and I can't imagine going back. We use primarily 3/16" and some 1/8" for non-structural areas. The only times that we really use bolts is if we have a pre-existing threaded hole (e.g., mounting a gearbox), we can't fit more than a couple rivets in a critical connection so we need the strength, or if the area is so tight that we can't get the rivet gun head in there to be able to pop it.

As some have said, drilling out rivets can be done very quickly, especially if you have a drill with a 3/16" bit at the ready. The big disadvantage is the shavings. Whenever we need to drill out a rivet, we have to cover up the electronics and be careful to take the coverings off nicely. This is a minor nuisance.

People complain about rivets loosening up, but we tended to have the opposite issue. Students almost never tighten bolts enough. We would always have to make bolts "mentor tight". One of the mentors (usually me) would come over and give the wrench another quarter to half turn after the student was done. Otherwise bolts would slowly loosen over the competitions. We very rarely have any issues with rivets loosening. Plus, if the rivet is popped, you know that it's the right pretension. I don't have to go over and tighten it a little more.

There are some other advantages. Rivet heads are pretty small compared to a typical socket head (and even compared to a button or low-profile head). Rivets can be put in blind. I don't have to worry about how to get the wrench on the back side. That's huge when planning your design.

The only real disadvantage to the rivets that we have come across is the difficulty of popping the 3/16" rivets. We have a lot of younger students and girls on the team. It can be difficult with a standard rivet gun. We have a huge massive rivet gun and a pneumatic rivet gun which both make it a lot easier, but the heads are a little bigger so it's hard to get in tight spaces.

Re: Rivets vs threaded fasteners
 

Being a coach of an FTC team, I've had experiance with kids using both options. In our lift system, we tried using nuts and bolts. We were going to loctite all of them, but we never got the chance, and after we added more to it, it was extremely difficult to get to them to tighten them.

We decided to use pop rivets the next year so they wouldn't loosen and unscrew after competitions. However, not all of them were pressed together tightly while they were used, so as a result they were loose and eventually broke. Our problem became much bigger now that we had to redo most of our pop rivets.

As a coach I feel irritated when all of their hard work just falls apart like that, and I see how frustrated they get too. That's why I've decided that we're going to use red loctite on anything that seems like it might come undone. However, we can't access every little nook and cranny, so we'll have to use pop rivits for areas like that.

My advice: Loctite nuts and bolts for easy-access areas, and then pop rivets for areas that you can't reach one side. Just make sure they press together everything tightly for the pop rivets.

Re: Rivets vs threaded fasteners
 

There are good and bad applications for both bolts and rivets.

We have some students who love to use the socket cap 1/4 screws and will stop building when they run out rather than the hex head ones. I guess they think they are cool, or something like that. Unfortunately, they tend to not put a washer under the heads and over-torque them causing the screw heads to "crush" the aluminum. One student over-torqued the screws holding the motor in one of the new clamping gearboxes and pulled the head completely through the plastic.

We also have team members who have trouble crimping a lug onto a 12AWG wire with a ratcheting crimper. Those same team members probably also have trouble tightening a bolt/nut properly. It is a never-ending struggle to teach the team members how to properly do what they need to do.


I would like to get our CAD guys to design using these. The difficulty is with installing them properly without the proper equipment (like what we have at work). The best may be to find a sheet metal sponsor who can install them properly. The downside with the cinch nuts is that a ham-fisted team members can inadvertently "punch one out" leading to a hard-to-fix situation since they can be installed in inaccessible locations.

Re: Rivets vs threaded fasteners
 

Are you sure this is a wise course of action? Red loctite can be (a) totally useless if the threads are cleaned a de-greased first and (b) the worst of both rivets and threaded fasteners (unservicable and difficult to drill out). I would suggest FRESH nylok nuts

We have had great luck installing PEM nuts with a machine vise, and a 1-ton arbor press can be had for <$100.

When PEM nuts have been popped out we have had good luck with holding the nut in place with pliers and re-cinching it with a light-duty cordless impact driver. It only takes a few moments, and can even be used to install the PEM nut in certain circumstances.

We are careful to use riv-nuts in truly 'blind' applications and PEM nuts in more accessible locations, where a press/clamp/pliers can get to.

Re: Rivets vs threaded fasteners
 

The general thought behind our wide use of rivets is that theyre faster, lighter, and less likely to come undone during competition. They may not be stronger that a bolt of equal weight, but we've found that 1/4 rivets are light enough and probably overkill in strength for our applications.

Re: Rivets vs threaded fasteners
 

We use a mix of rivets and threaded fasteners. Most often rivets are used for gusset plates on structural members - a couple of rivets can do a great job holding things together when all the stress is sheer. Threaded fasteners are used for situations where things need to come apart by design (for example, the top half of our robot this year detached for transport in the trailer), or when they are holding something in tension, or when we simply can't afford the height of a bolt head.

We're also big proponents of rivet nuts (or whatever else people call them). They are ideal when you need to bolt something to some tubing but don't want to go all the way through the tubing, or when access to a nut is going to be difficult. It just takes a little practice to get used to installing them!

Removing a pop rivet is quick and easy with a drill, and inserting one with a rivet gun is even easier. I can't count the number of times something has been riveted together, then later had to be taken apart and put back together for some reason. It happens all the time!

Re: Rivets vs threaded fasteners
 

It is important to have the capability to design for, and install both threaded fasteners and rivets. There are some situations like blind affixing structure to box or tube sections that are difficult without rivets. Depending on the situation - either could be used, and both would survive a season of robotic competition.

I would advocate only using Aluminum Rivets when possible. Steel rivets are a complete nightmare to remove from aluminum without a really sharp hardened bit.

We try to standardize on only a few fastener options: #6 Rivets, 10-24 & 14-20 UNC bolts. It makes it easier for the CAD team to know which clearance holes to use, and it limits the number drill bits in use (#10, #7, H) so there are less mistakes on hole sizes.

Re: Rivets vs threaded fasteners
 

Your strategy of mixing riv-nuts and cinch nuts makes perfect sense. Do you use the pliers and impact driver for cinch nuts that the arbor press cannot reach? We work at a school for the first part of the build season then move to oRyon Labs for the balance of the season. It will probably mean that the students will get more "exercise" to prepare them for moving the robot on the field. :D


We made the mistake of using a whole bunch of 1/4 inch steel rivets on parts of our chassis. We probably could have drilled fewer lightening holes if we had used 3/16 inch aluminum rivets.:(

Re: Rivets vs threaded fasteners
 

Since I was quoted in this thread from a post I made years ago, my challenge still stands regarding speed of rivets vs. bolts.

My challenge was only intended to be for people that claimed screws were faster.

As far as the challenge goes, it included cleanup and both "competitors" could use any power tool they wanted. However, the people using screws either had to (1) use a locking nut or (2) use loctite. I know I will bring a drill and a pneumatic riveter from Harbor Freight and will take on all challengers that think screws are faster.

Now, challenge aside, we use a combination of both depending on the job. I will never, ever use rivets in a tension (loads trying to pull "up" on the rivet) heavy applications.

When attaching sheet metal, we will only use rivets. PEM nuts (or the equivalent) are great if you know how to install them.

Again, it is really up to preference, but if you are asking for advice, then I would use rivets as the default and bolts should be reserved to where there are large pull out loading.

Re: Rivets vs threaded fasteners
 

My issue with cinch nuts is when they go bad, they can be a difficult repair. But they do have their place. You can also buy an hand installation tool that sets them with ordinary wrenches. Highly recommended if you use them.

Paul, the reason why your challenge get quoted is because it is a good example. Although I think that you would probably give the riveters a run for their money if you were the one handling the wrenches. :)

Re: Rivets vs threaded fasteners
 

If a vise or press press can't reach we'll use a riv-nut in the original design. The pliers and impact are generally only for 'emergency' situations, or where a bit of dis-assembly would be required to re-press the PEM nut. Sometimes the pliers aren't even needed.

So a friendly competition would be:

1) Start with a component, secured with whatever fastener you choose.
2) Remove the fastener.
3) Replace fastener with some form of anti-loosening feature.*
4) Bonus round(s) - repeat several times over.

Any power tools allowed.**
No assistants allowed.
No pre-loading of fasteners or tools.
Fasteners and tools may be laid out on the table.

I'll see about recording some trials and posting them on the YouTube. Could be fun! The Faster Fastener?

*I would argue that many bolts don't actually need this, especially when tightened with an impact gun, but as part of the competition that's fine.

**Using air tools can be really fast, but getting air tools at a competition venue can be... difficult, to say the least. I would argue that only electric or tools known to be readily accessible in the pits should be used. But, again, for a friendly competition this is fine.

Re: Rivets vs threaded fasteners
 

If you say you are faster with a riveter than with a nut and bolt, what if you had practiced with a nut and bolt and were more used to it than a rivet?
What I'm trying to say is that it's the cap on speed that matters, and a 1v1 test may not be perfect depending on experience.

Mainly for less-strong stuff and stuff we don't remove we use rivets. For stuff that needs to be stiff we make sure to have a lot of 1/4" rivets.
For removable assumblies (like our elevator this year) screws offer and advantage due to better accessibility; we can't exactly rivet something out 1/2" from our bellypan! So ti saves us space.

Maybe it's just the way we put on rivets, but they don't tend to work well in tension for us, and we need many to keep ourselves stiff and not loose.

Re: Rivets vs threaded fasteners
 

Just say no to red loctite, if you have to remove it you'll likely end up breaking, bending or stripping your Allen wrench and/or bolt. Red is supposed to be heated to be able to be removed. Blue is what I recommend for FRC use, it can be removed and usually does not cause the breakage/stripping that red does. Another option is the penetrating loctite, it is designed to be applied after the fasteners have been assembled. The one we typically keep in stock is the green version.

Nylock nuts or bolts are another good option.

Re: Rivets vs threaded fasteners
 

Since we seem to be trading horror stories in this thread, we haven't used many riv-nuts since the year we lost a match because a cross-threaded riv-nut spun and kept us from swapping our bumpers during a tight turn between matches. That and the fact it's difficult to get things to sit flush on top of (most) riv-nuts. The PEM nut fiasco on the old IFI sheet metal wheels has made me leery of those as well.

Re: Rivets vs threaded fasteners
 

Were you using steel or aluminum rivnuts?

Re: Rivets vs threaded fasteners
 

422 has evolved over the last 3 years to use 90% rivets, 10% bolts and other for fasteners. I think rivets are 1000% worth it in the long run, but you have to be proactive as a team when you design and manufacture parts you intend to assemble via rivets. I can drill out and replace rivets very quickly now because of all the time in 2013 and 2014 that was spent removing rivets on poorly thought out designs. If your parts are manufactured to the specifications of comprehensive, integrated CAD drawings, riveting is crazy easy.

Whether you use rivets or threaded fasteners, you're going to enjoy life more if you make coherent drawings and practice good machining, I just know how much I can hate life drilling out the 20th rivet on an assembly because somewhere along the way there was a screw-up. I do think the positive experiences students have had with rivets, weighed against the negatives, have helped condition better machining practices in house (The build lead and mentors 86'ing poorly done work also helps).

Todd, if you want to look past some ugly quirks of our robot when we're at VA (we sort of had to throw on some nasty looking gussets at the end to beat the snow) you can see where we use threaded and quick release fasteners and where rivets were used. Any static assemblies and subassemblies on the machine like the drive base and super structure, individual subassemblies on the lift with the shafts, grabbers, and carriages are all assembled through rivets. For the purpose of clean, universal replacements on some weird parts of the robot, we used threaded fasteners. Any point where one assembly or sub-assembly connects to another one is likely bolted on, or in the case of moving from transport to competition configuration, fitted with quick release fasteners.

Re: Rivets vs threaded fasteners
 

Thanks, everyone, for your constructive comments. You've definitely convinced me that we need to look more closely at transitioning to rivets whenever possible.