Is Welding Worth It?

[JamesCH95]

This is quite a vague question that depends much on the team. As Andy A said, 95 welds where it makes sense for us. Welding, especially with sheet metal, opens up a lot of design flexibility that we enjoy taking advantage of.

As with any choice in FRC it's not the choice itself that matters, but the execution. We design self-fixturing or easy-to-fixture components, accessible welding locations, and have access to a lot of nice equipment. A team should not expect to get a welder and see success, it will take practice and expertise to do well.

Originally Posted by InFlight

On your riveted joints failing. It's very important to use the correct grip length and hole size for the rivets. If your riveted joints are failing constantly, it's likely some sort of installation error.

Welding Aluminum requires either a MIG or TIG welder. This requires some considerable practice, and mentor familiar enough with the equipment to teach others how to use it safety. It can only be used with some types of Aluminum, stick with 6061.

While not as strong as a weld, it is also possible to braze Aluminum with a plumbing torch. I'd only try this with 6061 aluminum and use Bernzomatic AL3, Alumaloy, or Durafix braze rods.

Using a welder safely is no more difficult than using any other piece of shop equipment safely. In fact, a welder is probably safer than many pieces of shop equipment an FRC team might use.

I would not recommend 'sticking only with 6061.' After welding, an aluminum is generally in the "T0" state, in which 5052 has 28ksi UTS and 13ksi YS whereas 6061 has 18ksi UTS and 8ksi YS. This is just one example, there is much research to be done! Some alloys, such as 7005, can age at room temperature back to essentially full strength.

Furthermore, welding in FRC shouldn't be limited to aluminum only. Low alloy steels are easy to weld or braze, offer great strenth:weight ratios, and are not expensive. There are other design considerations for sure, but steel should be 'on the table' when discussing welding.

Originally Posted by marshall

Anyone have suggestions for which epoxy to use for bonding aluminum?

Surface prep is paramount here. Look at the epoxy supplier's suggestions for surface prep. I would recommend 3M DP 190, 420, or 460 for most applications, and Hysol 9309 for critical applications (it has glass beads to arrest crack growth and ensure an optimal bond gap). I would strongly recommend an elevated temperature cure rather than an ambient temperature cure for time and strength reasons.

[Mr V]

The first question that comes to my mind is what kind of rivets are you using? There are different grades and quality rivets. If you are buying them at your local hardware store in retail friendly packages chances are they are low strength. McMaster is one place that does sell high quality, high strength rivets also check for a local fastener supplier, Hi-Strength Bolt has locations in many areas.

I prefer rivets and/or nuts and bolts for the reason of quicker and easier repairs and changes.

Next time you are in traffic sitting next to a large truck take a look at the frame rail. You'll see that the cross-members and brackets are held on by rivets or nuts and bolts. That is so that those pieces can be replaced in the field in an expedient manner and without worry as to maintaining proper alignment or the skill of the welder and subsequent quality.

[marshall]

Originally Posted by IndySam

Adding a good epoxy along with your rivets can help eliminate rivet shearing and make a frame as strong as welding. It's a great way to add additional strength to a riveted frame.

Anyone have suggestions for which epoxy to use for bonding aluminum?

[IndySam]

Originally Posted by marshall

Anyone have suggestions for which epoxy to use for bonding aluminum?

We use Hysol E60HP

The long cure time is a bit of a pain but the extra strength it gives you is worth the wait. We have used it for years with great results. Rough up the surfaces you are bonding and you aluminum will break before the bond does.

[AdamHeard]

Originally Posted by IndySam

We use Hysol E60HP

The long cure time is a bit of a pain but the extra strength it gives you is worth the wait. We have used it for years with great results. Rough up the surfaces you are bonding and you aluminum will break before the bond does.

We've been using E-120HP (same family) and have been happy with it.

We clean and degrease the surfaces after abrading for a better joint as well.

[electroken]

We've discussed welding but haven't gone down that path. Our frames for the past 3 years have been riveted with 3/16" stainless rivets (they were free...). We sheared no rivets and the frame was easily repaired when it needed to be.

[techhelpbb]

No one has mentioned brazing aluminum:
http://muggyweld.com/super-alloy-5

[JamesCH95]

Originally Posted by InFlight

On your riveted joints failing. It's very important to use the correct grip length and hole size for the rivets. If your riveted joints are failing constantly, it's likely some sort of installation error.

Welding Aluminum requires either a MIG or TIG welder. This requires some considerable practice, and mentor familiar enough with the equipment to teach others how to use it safety. It can only be used with some types of Aluminum, stick with 6061.

While not as strong as a weld, it is also possible to braze Aluminum with a plumbing torch. I'd only try this with 6061 aluminum and use Bernzomatic AL3, Alumaloy, or Durafix braze rods.

Originally Posted by techhelpbb

No one has mentioned brazing aluminum:
http://muggyweld.com/super-alloy-5

[techhelpbb]

Originally Posted by JamesCH95

Well they did not mention MuggyWeld.
So I think you could have snark lite on that but point taken.

[FrankJ]

Originally Posted by marshall

Anyone have suggestions for which epoxy to use for bonding aluminum?

You can go down the rabbit hole with this. But. More important than the specific epoxy is surface prep. Epoxy works best in shear with lots of surface area. Preferably you would want to strip the oxide layer of the aluminum. At the very least scuff it with 80 grit. The surface should be thoroughly cleaned and de-greased. Reference one
West systems has a lot of how to for epoxy.

[The Swaggy P]

Welding definitely helped with keeping stress points from bending and/or partially breaking.
Yes, it is expensive when compared to riveting. But the amount of metal shavings created by drilling your own rivet holes makes for a lot more cleanup, and risk of electronics shorting.

[Rivet Man]

Originally Posted by The Swaggy P

Welding definitely helped with keeping stress points from bending and/or partially breaking.
Yes, it is expensive when compared to riveting. But the amount of metal shavings created by drilling your own rivet holes makes for a lot more cleanup, and risk of electronics shorting.

Hi The Swaggy P,

I'd like to address your point about rivet holes creating more cleanup and risk of electronics shorting.

Ideally you should be drilling these holes before installing any electronics! But in the off chance that you have to I'd suggest having a two man crew (never run equipment alone! HSA wouldn't like that!) Where one holds a rag and a vaccum while the other drills. Additionally I would suggest placing a cloth over top of any vital electrical equipment underneath. This should both protect your equipment and reduce the cleanup!

Hopefully this makes your life a little easier and your fastening experiences a bit brighter. Happy popping!

Also happy Memorial day weekend. God bless our troops.

Best Regards,
Rivet Man

[SystemS]

welding is worth it if your design requires more customization than can be done to a kit bot frame. When a student is capable of welding a chassis correctly, the first time, it is quick and not a bad idea. One year a sponsor did it for us it was done wrong, after 2 weeks. That year it would have been better for a kit bot frame.

[Clayton Summerall]

Originally Posted by SystemS

welding is worth it if your design requires more customization than can be done to a kit bot frame. When a student is capable of welding a chassis correctly, the first time, it is quick and not a bad idea. One year a sponsor did it for us it was done wrong, after 2 weeks. That year it would have been better for a kit bot frame.

Why do you have to weld to have a not kitbot frame?? This year we had an 090 bent sheet metal chassis that had about 600 rivits in it with no welding.

[GeeTwo]

Originally Posted by SystemS

welding is worth it if your design requires more customization than can be done to a kit bot frame. When a student is capable of welding a chassis correctly, the first time, it is quick and not a bad idea. One year a sponsor did it for us it was done wrong, after 2 weeks. That year it would have been better for a kit bot frame.

Originally Posted by Clayton Summerall

Why do you have to weld to have a not kitbot frame?? This year we had an 090 bent sheet metal chassis that had about 600 rivits in it with no welding.

+1. Our 2014 Aerial Assist chassis was c-channel and tubes bolted together using flat angles and Ts as gussets. Even as violent as AA was, frame strength was not one of our problems.