MIG welding and advice

[techhelpbb]

If that MIG unit is less than 200A (it says 125 on the front) you'll likely run into some issues with aluminum.
As mentioned you want 100% argon as well.

My Hobart 210MVP has a spool gun but there's limits of what you pull off with low power delivery.

[ttakashima]

You will probably only be able to weld up to 1/8 maybe 3/16 inch aluminum plate with that machine. We have a 180 amp Miller TIG welder on campus which can weld a little under 1/4 inch Al. When we have our robots welded, some of our thicker components (1/4 - 1/2 inch) have to be taken to our welders off campus shop with a more powerful machine.

[FrankJ]

Originally Posted by MrBasse

... before you give out too much information. MIG and TIG are abbreviations for the same process (GMAW),

In practice MIG & TIG are very different. In MIG your electrode becomes the filler & is consumed. In TIG your tungsten electrode is not consumed & should never touch the weld puddle. While you can buy machines that do both the setups are very different.

[MrBasse]

Originally Posted by FrankJ

In practice MIG & TIG are very different. In MIG your electrode becomes the filler & is consumed. In TIG your tungsten electrode is not consumed & should never touch the weld puddle. While you can buy machines that do both the setups are very different.

Exactly right, but both MIG and TIG fall in the category of Gas Metal Arc Welding (GMAW) by using a shielding gas (Argon, Carbon Dioxide, etc.) rather than Shielded Metal Arc Welding (SMAW) using a flux coated filler material. What you said is exactly what I wanted the poster to look up and learn on his own.

[FrankJ]

Not to be confused with a flux core wire welder which looks a lot like a MIG.

[MrBasse]

This welding stuff sure does get confusing... We should all just switch to glue

[FrankJ]

Thermo Setting? Synthetic monomer? Synthetic polymer? horse glue? Or my personal favorite Gorilla glue?

[DonRotolo]

Originally Posted by FrankJ

Thermo Setting? Synthetic monomer? Synthetic polymer? horse glue? Or my personal favorite Gorilla glue?

Friction stir welding. That's what I want to try. I have my cordless drill....

Gorilla glue? Why in the world would you want to glue gorillas together?? (I can see why you'd want to glue horses together though - increased horsepower, of course).

[FrankJ]

Picture a gorilla on top of a pyramid swatting Frisbees out of the sky while holding one of the Refs. Then you will understand the need for the glue.

[DampRobot]

Originally Posted by DonRotolo

Friction stir welding. That's what I want to try. I have my cordless drill....

Handheld friction stir welder... Yeahbuddy!

SpaceX does friction stir welding to make their rocket bodies, it's really a extremely cool process. Worth a google for all those looking at this thread.

On a side note, I've heard the reason that we beat the Russians to the moon was because we had better welders. Ours could figure out how to weld tanks which were good enough to hold liquid hydrogen, whereas the Russians could only make kerosene tanks. We ended up with the slightly smaller and more reliable Saturn V for our moonshot, and they ended up with that massive kerosene powered rocket that looked like a Christmas tree--which turned out to be impossible to control in the sky.

[DonRotolo]

Originally Posted by DampRobot

We ended up with the slightly smaller and more reliable Saturn V for our moonshot...

I have never before seen the words "smaller" and "Saturn V" used in the same sentence. Wow.

[Ian Curtis]

Originally Posted by DampRobot

Handheld friction stir welder... Yeahbuddy!

SpaceX does friction stir welding to make their rocket bodies, it's really a extremely cool process. Worth a google for all those looking at this thread.

On a side note, I've heard the reason that we beat the Russians to the moon was because we had better welders. Ours could figure out how to weld tanks which were good enough to hold liquid hydrogen, whereas the Russians could only make kerosene tanks. We ended up with the slightly smaller and more reliable Saturn V for our moonshot, and they ended up with that massive kerosene powered rocket that looked like a Christmas tree--which turned out to be impossible to control in the sky.

For what it's worth, this is one of those great sounding stories that is almost certainly false. The Soviets never invested in hydrogen rocket engines, despite repeated funding requests from Korolev, who was basically their Von Braun. As such the Soviets were way behind, particularly because the military had been building the engines for the Saturn V long before NASA even planned to go to the moon. The military recognized that the engines are typically the schedule driver on aerospace projects, and figured they could develop vehicles to go with them later. Or another way, they just wanted bigger more expensive toys than the other branch, since the Air Force and the Army both wanted in on the missile game.

The N1 was actually lighter (still weighing several million pounds) and shorter (still nearly 350 feet tall), than the Saturn V, but it had a ridiculous number of rocket engines (43!!) compared to the Saturn V's 11. It also had an additional stage to make up for the performance loss of Kerosene vs. H2.

Taming Liquid Hydrogen is a wonderful book (if you're a huge nerd like me ) that NASA put together that describes the technical and political challenges of designing the Centaur upper stage that is still in use today.

I love Kerosene Christmas Tree... great name!

EDIT: Moral of the story I forgot: Rocket development (and aerospace product development in general) is so complex it rarely gets held up for just one thing.

[EricH]

Originally Posted by DonRotolo

Friction stir welding. That's what I want to try. I have my cordless drill....

Originally Posted by DampRobot

Handheld friction stir welder... Yeahbuddy!

SpaceX does friction stir welding to make their rocket bodies, it's really a extremely cool process.

Handheld stir welder? Try a mill instead, it'll work slightly better. (Trust me on this. I spent a good portion of my work day today on one of the SpaceX stir welders--and that's actually pretty typical for me.)

BTW, friction stir welding is one of the FEW new technologies with almost no practical application to FRC robots. Maybe the sheet metal bots could use it, but even they'd have a hard time. Not saying it isn't cool to watch, though.

[bake]

Wow, A lot of confusion about welding here. MIG (GMAW) and TIG (GTAW) are not related at all except that they use an electric Arc. For your application with your welder a spool gun would probably be the best bet for Aluminum MIG. It is difficult(but not impossible) to push the soft aluminum wire through the liner. Argon is the correct shielding gas. The filler wire will have to match the material being welded. Cleaning is the key to Aluminum. The oxidation that forms on Aluminum has a higher melting point than the Material itself. Wipe parts clean with Acetone. SS wire brush to remove oxidation. MIG Aluminum is difficult but can be done. If you have any specific welding questions I can probably steer you in the right direction.

[MrForbes]

Just to throw a monkey wrench into the whole discussion....in 2011, we built a steel robot chassis. A freshmen borrowed a MIG welder, and did all the welding. If you use thinwall steel tubing, the weight isn't really very much more than using thicker wall aluminum. And MIG welding steel is easy. Even I can do it.