Is Welding Worth It?

[Anthony Galea]

We outsourced the welding of our shooter together to a sponsor for the first time ever because rivets couldn't handle the stress of the ball being shot over and over again, leading to a weaker shooter. We riveted the gussets/metal together, then took it to our sponsor and they welded it for us, and we didn't have any problems. It was definitely worth it. If none of your team has had welding experience and is very confident, i would recommend taking it to get it welded.

[messer5740]

Our team had been told to watch out for aluminum welding for it may give extra strength, but experience is needed and bolts and nuts can hold the frame together just as good. The only downside of that is be prepared to loose some bolts and nuts, but the pros are that you can detach parts in case repairs are needed.

[Andy A.]

95 welds were it seems to make sense, usually to reduce weight or to simplify a structure. It's not our first pick, but sometimes it solves a lot of problems. But we have a really good welder, and work in a welding training shop. Without those resources I don't think we could justify the time and risk of having welding done by a 3rd party.

We rarely use rivets, though. The basic frame elements are generally put together with screws and captive threaded inserts like rivnuts and pemnuts. We really like the easy serviceability screws give us at competition and during testing. There's also a comfort factor in the relative strength of machine screws.

Installing the inserts has a significant upfront investment in tools materials and time, and probably a measurable cumulative weight penalty. But I think it pays off over the course of a season.

[Katie_UPS]

Originally Posted by MrBasse

Why do you grind your welds down? Are you looking for a smooth appearance or for a strong joint? In my opinion, nothing looks better than a smooth stack of weld material laid down just right especially on aluminum.

I don't really remember (that was over 5 years ago) but my guess is that it was either an aesthetic choice made by someone else or a "we need this surface to be flat" type of situation. Either way, I guess I was glad we did, as it caught the bad welds before they were a major problem.

[MichaelBick]

1836 hasn't welded for the past 4 years, and has been pretty happy. However, rivets, including those in highly stressed shear applications, can loosen up, creating a less than ideal joint (for comparison, we do use aluminum body aluminum mandrel rivets). It in the high load applications that we are considering welding joints as an addition to rivets and gussets.

[techhelpbb]

As mentioned aluminum welds are typically not as strong as the aluminum itself. Welds can add material so they can add weight. Welds can embrittle material. Welds can cause oxidation. Welds can be deceptive.

Rivets and bolts add material and may be even more prone to do so. Rivets and bolt holes can weaken the material. Dissimilar materials can cause corrosion at the contact points.

All of those things aside - the design may specifically make one choice better than another. I can certainly see with the pits FRC uses that welding can be inconvenient if it fails. Then again maybe if it fails you just bolt or rivet at that point.

I don't think we have the welding equipment at Mount Olive High School anymore.
So if I want to cook some metal I have to do it at home, take it to a friend or take a trip to NextFAB.

[Ryan Dognaux]

If you have photos of where your rivets failed, please post them. That will make this discussion 1000% more beneficial to your team and other teams.

Your rivets failed most likely due to a poor design - either you're using rivets that are too small (we use 5/32", sometimes 3/16"), not using enough rivets, need a better gusset design, too high of stress to the affected area, etc.

We've used versa-construction with rivets and gussets for 3 years now and have been very pleased. It's simple, our students can build almost anything with it, and we've had no failures that weren't our own fault due to a poor design.

Buy a pneumatic rivet gun and a compressor if you can manage it - it will make your assembly go so much faster and we've found that they hold just as well if not better than ones done by a hand riveting tool.

[Fusion_Clint]

Depends.

We use a MIG welder we received through a grant, we purchased a spool gun for it, and we teach a few of our kids to use it.

We normally use 1/4" aluminum plate for our drive train and weld the cross members into place. This year we also welded our shooter chassis (1/8" aluminum) together.

47 matches this year, not one broken weld.

[Spark]

Originally Posted by techhelpbb

As mentioned aluminum welds are typically not as strong as the aluminum itself. Welds can add material so they can add weight. Welds can embrittle material. Welds can cause oxidation. Welds can be deceptive.

Just adding that although welds do weaken metal you have to keep in mind that drilling lots of holes in a piece of metal for rivets or bolts can weaken it as well. Welds, if done RIGHT are the strongest option, but rivets and bolts are faster.

[AdamHeard]

Originally Posted by Spark

Just adding that although welds do weaken metal you have to keep in mind that drilling lots of holes in a piece of metal for rivets or bolts can weaken it as well. Welds, if done RIGHT are the strongest option, but rivets and bolts are faster.

This is an impossible statement to make accurately with so little information.

There are applications where each is the best.

[FrankJ]

Not to mention that when you get to <0.100" material, the skill level required to weld aluminum goes way up. Nothing like burning a hole is the last weld, killing the entire piece to ruin your day.

If you have the resources, welding is great fun. If I had the resources in place (A good welder for aluminum is $1000+) it is a good resource. If you don't there areas that would get more bang for your buck. YMMV

[Chief Hedgehog]

Originally Posted by FrankJ

Not to mention that when you get to <0.100" material, the skill level required to weld aluminum goes way up. Nothing like burning a hole is the last weld, killing the entire piece to ruin your day.

If you have the resources, welding is great fun. If I had the resources in place (A good welder for aluminum is $1000+) it is a good resource. If you don't there areas that would get more bang for your buck. YMMV

$1000 is getting away cheap. And with GTAW (TIG) welders, a $1000 welder buys you very little in the way of an good amp control such as a pedal or thumb trigger. If you TIG weld without the amp control, it becomes even more an art to get little in avoiding edges turning down - it requires more table time that many teams cannot afford to offer in a short build season.

We recently purchased a Thermal Arc 161 after borrowing 5542's and it did the job. However, if you saw our 2016 robot, we also have a steel subassembly that carried most of the carnage that the Strongholds defenses mustered.

We also used rivets extensively and none broke - replaced, but never failed.

We will continue to use the GTAW process as it provides students a way to learn a new welding process - but it will never be a prominent process of joining for our robots.

Oh - and NDSU's Bison Robotics Greenhorns Robot was named Rivvet for a reason. It was completely assembled using rivets.

[sanddrag]

A high school student can absolutely learn to TIG weld proficiently with enough practice. In fact, my student's welds were hanging on Einstein, on 330's robot....

[Dylan179]

[tap13]

Welding can be a lot of fun and in my opinion has more pros in terms of creating a lighter and more durable chassis, however there will be some issues if we are letting the students weld. We need to make sure we have a ventilated and high ceiling shop, PPE needs to be addressed to everyone, and who ever is welding needs to be highly supervised. Another perspective is just creating a better designed robot. Stronghold was tough.