Welding equipment

#1

My team is looking into getting some welding equipment.
we were wondering what equipment other teams use? what are the rules for using it? Are you capable of both aluminium and steel? How often do you use it?

Any information would be helpful. No one on our team has ever done welding but we should be able to bring someone in to help teach us.

#2

My team uses Miller TIG and (much less comonly) MIG.

A mentor uses it, or a student uses it with direct supervision until they’ve proved competency.

Yes. Also titanium and bronze.

Several times per season. We try not to go weld-happy, often rivets and bolts are easier. But when we do need to weld it is a wonderfully enabling technology.

If I were buying a machine for an FRC team I would require the following specs:

-200A max current
-AC output with balance capability (critical for aluminum)
-Pedal control (I know trigger control sounds great, but I’ve never seen someone use it as well as a pedal)
-Water-cooled torch (air-cooled torches work fine, but the cords are so stiff and heavy that it can significantly detract from learning and handicap weaker welders who might be quite skilled)

You should look at Everlast. I’ve got one in my garage that I’ve been quite happy with. They’re ~1/2 the cost of Miller or Lincoln with the same or better feature set.

Also consider getting a bottle argon and argon/helium mix. 50/50 argon helium makes welding aluminum remarkably easier than pure argon.

1 Like
#3

There are a lot of welders on amazon for a much lower price would any of them work in the long run for aluminium and other metals.
an example is https://www.amazon.com/REBOOT-Digital-Inverter-Welding-Machine/dp/B07N1DJPGJ/ref=sr_1_8?crid=2HXVML9P7FKIT&keywords=200a+mig+welder&qid=1557245256&s=gateway&sprefix=200a+mig%2Celectronics%2C239&sr=8-8.

#4

From your own link:

This machine is not listed as having AC output and thus shouldn’t be used to weld aluminum.

I can’t comment on the durability of a particular machine that I haven’t used long-term. However, with larger pieces of equipment like this, often you get what you pay for.

#5

Another mentor on our team likes to say when considering if he’d bring his TIG welder from home that you have different quality (with proportional cost), starting with some basic cheap TIG machine at the low end, then some increasing quality until an industrial TIG machine, and finally you reach the highest cost TIG which is the student trainer, because it is going to get beat up and needs to withstand that. So he says he’d never bring his in because it’d be broken in no time.

I’m no welder, but we have stuck to doing mostly arc welding for steel. We shopped out some aluminum welding this year, and next we’ll do that or see if a couple students could access the school shop for aluminum. It is definitely nice to have in house, but mainly it would be for doing welding on the chassis, which typically is a one-time thing. This year we did an all steel chassis in house (which was around 11-12 lbs frame), but I think we will try to lighten that a little.

We have another task, we have been stopped from welding in our building because of concerns about fire and ventilation issues. So this summer we need to make some proposals to our superintendent about how to satisfy that it can be done without potential issues. I’ve read through some hot work requirement sheets, so adding more ventilation, welding curtains, designation/clearing a space, and having good training and practices, are some things I think we should do.

#6

There is a lot to learn about welding (and the information can be hard to find). Here is my brain dump. I apologize in advance for this being all over the place.

When picking a welder my criteria is similar to @JamesCH95 but I tend to favor Miller/Name brand welders with digital displays over anything else (I use air-cooled without any issues btw). Digital displays are better for consistency since you can see exactly what amperage you are at.

The Chinese welders on amazon are often usable but less than ideal. You do not want your welder to hinder your ability to learn. I would suggest saving up around 7-8k before investing in any welding equipment. 7-8k will cover the welder, gas, tungsten, filler rod, diamond grinder, Hoods, gloves, clamps, jackets, etc. which is what you need to get started.

Since you said that you haven’t ever welded before, I will explain the items above. TIG (Tungsten Inert Gas) welding uses a tungsten electrode (thin tungsten stick) and a gas bubble (argon or argon-helium). The arc heats the piece of metal while the gas shields the weld from oxidation. The metal is grounded using a grounding clamp and then the arc forms between the tungsten and the metal. Filler rod is introduced to add material and strengthen the welded area. A hood is the mask that you use to cover your eyes and face while welding. Make sure to buy the automatic hoods which use batteries and a sensor to auto-dim when you strike your torch.

Tungsten comes in multiple different variants. I prefer 1/16" diameter 2% thoriated and have yet to see a reason to change that. Tungsten is largely up to preference. Another factor which can change your tungsten is the cup on the end of your torch. Get some nice gas lens cups with different sizes and you will find which one is best for you.

Welding takes hours of practice to be able to weld steel, triple that for aluminum, and 20x to weld either really well. Practice practice… practice. Start small with sheet steel and practice tacking, welding two pieces together without burning through, and then graduate to thicker or more complex welds.

A good weld is a strong weld, a strong weld is a clean weld. Oxidation will ruin the strength of your weld and also causes it to “splatter” when hot. Using the proper flow of argon to shield the weld is crucial. There should be zero splattering when TIG welding correctly. Another crucial part of welding is the prep work. Every material introduced into the weld needs to be sterile. This means cleaning the filler rod, work piece, table around the work piece (which better be metal not wood), and the tungsten. Tungsten is cleaned by using a diamond grinder to create a point. The angle varies by preference. Lets just say 15 degrees or so. A perfect point means a better weld since the arc will form in the exact spot you point the torch. You will need to grind your tungsten as you weld since the tip wears away.

A good rule is as follows:
Buy a 10 pack of tungsten and grind each one. As the tip erodes away, switch to the next stick. Often times people will sacrifice weld quality since it can be frustrating grinding your tungsten every 5 minutes. With a 10 pack you can make it 50 minutes without grinding. Yes you need to regrind the tungsten if you touch the work piece.

End rant (well sort of, I am sure I will think of something to add in an edit).

1 Like
#7

Nelson replied above about 1108, but more specifically, we just use low powered wire-feed flux core welders and only on steel. You can get into one for really low money and most of what we build is just thin-walled steel tubing, so we don’t need any real power. Stick welders are bad at thin tubing.

We use a Hobart 140 one of the dads has loaned us, or sometimes I bring my Century 135 from home. Both under $500 new, both US made.

TIG and true MIG would be both be nicer than flux-core but from a cost-effective standpoint, gas is more expensive and not really better. Flux core welds need ground, but we grind all our welds anyway.

I understand that there is aluminum wire available for MIG welders, but we haven’t tried it. Welding is a great way to make a custom assembly when you don’t have a router to make precision holes for rivets or carbon fibre to mold.

#8

Miller! The miller welders we use for FRC do daytime duty as votech teaching machines, and nighttime duty as adult teaching machines. I’ve never used a TIG machine better than a Miller Dynasty, but that was ~$15k!

Also, if you’re welding steel up, I’d encourage you to look at 4130 steel for your frame. It’s wonderfully strong, can weld like a dream, and TIG-brazes beautifully with silicon-bronze.

So can I, and many other people. When I was teaching welding a petite young woman struggled really hard welding with an air-cooled Miller setup. No tips/tricks/help was enabling her to weld at a high quality level. On a hunch I moved her to a Lincoln machine with a liquid cooled torch. An objectively worse welder, but she was no longer straining hard to keep the torch steady and became one of my best welders.

It would be an outright shame for an FRC team were to miss out their potentially best welding talent because they tried to scrimp a few bucks by going with air-cooled over water-cooled.

Maybe you should change that because Thoriated tungsten is radioactive.

Are the normal doses of this material dangerous? Probably not. However, when students are involved who may not be aware of the risks, or if you do the right thing and tell their parents ‘your child is working with a radioactive material’ (which any ethical welding instructor should be doing) the optics of the situation are not good. There are plenty of other tungsten electrode alloys that do not have these health risks that provide equivalent or superior performance.

I use lanthanated electrodes because that one formulation will do everything well, especially the super-thin materials I tend to weld these days.

[quote]Lanthanated (Color Code: Gold)
Lanthanated tungsten electrodes (AWS classification EWLa-1.5) contain a minimum of 97.80 percent tungsten and 1.30 percent to 1.70 percent lanthanum, or lanthana, and are known as 1.5 percent lanthanated. These electrodes have excellent arc starting, a low

burnoff rate, good arc stability, and excellent reignition characteristics—many of the same advantages as ceriated electrodes. Lanthanated electrodes also share the conductivity characteristics of 2 percent thoriated tungsten. In some cases, 1.5 percent lanthanated can replace 2 percent thoriated without having to make significant welding program changes.

Lanthanated tungsten electrodes are ideal if you want to optimize your welding capabilities. They work well on AC or DC electrode negative with a pointed end, or they can be balled for use with AC sine wave power sources. Lanthanated tungsten maintains a sharpened point well, which is an advantage for welding steel and stainless steel on DC or AC from square wave power sources.

Unlike thoriated tungsten, these electrodes are suitable for AC welding and, like ceriated electrodes, allow the arc to be started and maintained at lower voltages. Compared with pure tungsten, the addition of 1.5 percent lanthana increases the maximum current-carrying capacity by approximately 50 percent for a given electrode size.[/quote]

I learned how to weld on aluminum. I then started teaching aluminum first. I am generally able to have a student laying a decent bead within 2 hours, some more some less. While it shouldn’t be taken lightly, start-up training time can be somewhat short. After ~12 hours of shop time (really 3-4 hours of torch time each) my students were able to make a sheetmetal aluminum weld that passed a tensile test.

I know that I picked on your post pretty hard. Most of the information you supplied is good, especially the three Cs of welding: clean, clean, clean. The three points I addressed are admittedly pet peeves of mine that I feel compelled to speak up about.

1 Like
#9

I’ll second this bit; James managed to teach me to weld, and I’m as stubborn and ornery a student as there ever was. The timeline’s about right. I’m no master of the craft, but a couple hours of messing about and my welds are passable, if not pretty. I wouldn’t want to hang out underneath one of my welds, but I trust them not to fall apart sitting on the lab bench.

I think of it like machining. It takes a few hours to come to grips with all the dials, levers and math on a mill, and at that point you can probably manage to do most of what you want to do. The next 9,990 hours of shop time gets you the speed, efficiency, and ornery attitude that everyone admires about machinists.

#10

I guess that depends on how strong you want the weld to be…any weld that is structural, should not be ground (unless it is in preparation for another weld over it, as when doing multiple passes on thick material).

Thanks James for the insights about teaching students to weld aluminum. It took me quite a bit longer (I took a TIG class at the local community college last year, but I’m an old man), and I’m still not very good at it. I can do ok with ferrous materials.

#11

We have been welding our robots for many years, the past 3 years has been by myself. I’ve used probably 4 different welders over the years, all Millers. I’ve been welding since I was 6, so I have quite a bit of experience and I have a large bias towards Miller, not going to try to hide that.

If you can afford it, water cooling is nice for long and heavy welding. We created our own “cheap”, water cooling setup using a 55 gallon barrel and a pump. So far we had gone through 6 pumps in the past 3 years. We kept using a DC motor/ pump which every time killed the built in inverter, requiring a new pump. Ths last pump setup used an industrial motor and a relatively large, heavy pump attached (dont know part #s). But in the end, it’s working pretty well.

Welders wise, all the ones I have used for TIG are industrial. Our first one the team used since I’ve been around was actually a mentors that he bought at an auction years prior. This welder was from the 50s, and it welded horribly. The pedal had no control, tungsten basically had to touch to create an arc. The next one was a sponsor/ family friend. It was newer, I believe made around the turn of the century and was night and day better. The welds I laid using the 60 year old one were complete garbage but same technique on the newer welder produced extremely clean welds, that was hard to tell that a sophomore in high school created. The last welder the team has used is the same for the past two years. We have a welding shop down the road that our mentor does a lot of work for. He noticed they had a couple welders sitting in the back that didnt work. When asked what was wrong, he was just given them. He pieced them together to make one and it’s been great. Almost as good as the one our sponsor let us use. Even though it was a pain, the next person I teach to weld, I would love to use the old welder. If you can weld on that, you can weld on anything truly.

For tungstens, we pretty much strictly use E3 (purple) or Pure Tungsten (green). We stay away from the thoriated mainly for health reasons. We size of tungsten we use is typically 3/32 I believe, but we have used larger and smaller, it just depends.

Filler metal, we have used between 1/8 and 1/16, really depends on what we are doing.

When welding aluminum, it’s very important to pre heat. Aluminum likes to draw heat away so by pre heating with a propane or similar torch, it allows you to instantly start the weld almost when you try to. Make sure to wire brush the aluminum also. Aluminum does create an oxidization coating, while minimal, can cause contaminated welds. Even glass blasting or something similar helps prep the area very well.

I could probably go on for awhile with tips and stuff I’ve learned over the years.

#12

Can you elaborate on ‘gas is more expensive and not really better’? That’s a pretty bold statement.

This! You generally should not grind welds flat (you can/should if the WPS calls it out, but I doubt that more than a handful of FRC teams have WPSs for their joints). The extra material from the weld is needed to ensure proper joint strength for most applications. If you’re grinding your welds and not failing anything currently, consider moving to a thinner material and not grinding.

I have seen too many workable welds get ground off and then fail later because there wasn’t perfect joint penetration to condone the practice of weld grinding in structural situations.

You’re welcome. All I can say is keep up the practice!

@andrew-5678 et al. When I was getting my feet under me I used this website a lot. The owner, Jody, is wonderful for answering super-weird questions not covered by his video set. Like, how should I weld ball-bearing steel (you shouldn’t, too much carbon).

I avoid pure tungsten like the plague. I bet you’d see better performance with E3 over pure tungsten in all situations. Try it out! Pure tungsten likes to ball up, which reduces arc control. In the worst cases, like if you bump your torch on something, pure tungsten can drip into the weld pool. No good. Especially if you need to machine it later, machinists hate finding tungsten inclusions in aluminum. #learnfrommymistakes

I size tungsten and filler material to match what I am welding. Fit-up should also be gauged from material and filler thickness. For example, if you’re welding #11awg alumnium (.09in thick) you should closely match in tungsten size (3/32, .093) and filler size (also 3/32) and have no gaps over 3/32 (i.e. you can’t fit the filler wire through the joint). Of course ideally the joints are completely closed before welding.

Wandering topics a little bit…

I will reiterate my suggestion for TIG welder because of the material flexibility. You can use silicon-bronze to TIG-braze materials that are ‘unweldable’ like high-carbon steels. Plus it looks awesome. I’ve used silicon-bronze tig brazes on robots in the past, specially on metals with weird fillers that ruin welds, but that tolerate brazing no problem.

You can pivot to do titanium if needed. These were some super-weird parts for our 2015 robot that we stuck together in a few minutes.

Closing up some aluminum sheet metal in 2019.

Repairing an out-of-production steel casting for a friend’s Jeep.

All of these welds can be done on the same machine, with the same gas, just with a few knob turns, lever flips, and a variety of fillers. No hardware reconfiguration needed.

#13

@JamesCH95

I guess I should’ve been a little more specific:

I learned on an air cooled TIG without any issues. Torch control was one of those things that I had to figure out. I wear the hose around my neck always when welding to assist with this.

As far as the amount of time required to make FRC quality welds, I agree with ~2 hours to get a bead and so on. I realize that it might sound as though I am telling CD that they will not be able to weld without years of practice but that is not at all the case. My intent was that I stress the importance of practicing without getting discouraged. Welding can be frustrating at first and I don’t want anyone to say “Oh I can’t weld” because I think it is a skill that anyone can work on and be able to do.

Some more general info about welding for those who are reading:

Believe it or not, Aluminum “rusts” better than steel! Steel rust turns yellow/brown/orange while aluminum gets a layer which is basically invisible. The oxidation layer forms faster than steel would ever rust. To remove this, I use a wire wheel and lightly grind away at the surface. This is the exact way I prep all of my aluminum welds. Be sure to only use the brush on aluminum and not steel. You do not want to cross contaminate the brushes.

For steel tubing (like chromoly (4130)) I scotch-brite the surface until shiny and then use acetone to remove grease/grime. Do not put acetone on the tungsten since it will cause the arc to dance.

Tack welding refers to a small weld bead which holds a part in place. Tacking is great for figuring out positioning of parts so that they get welded perfectly in-spec. Tacks can be removed by heating again or by grinding.

When welding a large and thick aluminum part, it is often beneficial to preheat the part with an oxy-torch which reduces the arc time required to melt the surface metal.

When creating a drivetrain (or anything) using tubing, put material in between the parts to keep the angles at 90 degrees. When you weld, the parts will pull as the weld cools which can change dimensions. In industry, Jigs are used to prevent this but for FRC purposes you can get away with some clamps. Weld as much as you can before removing the clamps to prevent further pulling.

Last note, welding arcs give off UV light (like the sun). So you can actually get sunburns from welding. Wear proper protective gear to prevent them (and maybe even sunscreen).

#14

Not much to add here. We have a Miller Diversion 165 that we’ve used probably 100+ days/yr for the past 6 years. Good super simple machine that does everything we need for FRC. Occasional glitch where we need to power off and back on, but otherwise reliable performance and beautiful welds with 3/32 E3 tungstens.

1 Like
#15

To add to what sanddrag posted: the Diversion is a wonderful little welder that would likely cover a vast majority of usage for any given FRC team. The Diversion was one of the welders I used to teach with and what my FSAE team brought to competitions. The only time it will fall flat is trying to weld 3/16 and thicker aluminum plates together.

#16

Funny, I’ve been using 3/32 pure tungsten (green) to weld aluminum for thirteen years and have never had an issue with it.

On topic, we use a Miller 300A with digital display, pretty much only ever weld Aluminum with it, and use it once or twice a season, generally–and sometimes not at all. If we need something steel welded, we turn it over to the metals class and let those kids do it.

#17

Pure tungsten is… fine. Some will say ‘pure tungsten is pure cr*p’ which is a bit of hyperbole. The general consensus is that pure tungsten works best on older, transformer style machines. It can work on inverter welders, but it is counter-indicated on certain inverter TIG welders.

You will likely find what I did - superior current carrying capacity and arc control with lanthanated tungsten over pure tungsten in AC welding.

#18

I’ll have to check them out. I make no claim to at all being an expert–I do things the way I do because that’s how I was taught to do them, and the (very accomplished) machinist mentor we’ve had for many years, who has forgotten more than I will ever know, does it that way…

1 Like
#19

We’re welding mild steel thin-wall tubing . Most of our robot is made with 1/2 square section .065 thick. So almost always, our welds are stronger than the metal anyway.

It’s been a while since I bought argon, but I seem to remember it wasn’t free. I think a refill is about $40 for a short (80cf) bottle. Lasts a couple weeks–so three in a build season. Flux core is about $20 for two pounds, where MIG wire is $12. We use maybe five in build season. So flux is 5 x $20 = $100 for build season, where MIG is ($12 x 5) + ($40 x 3) = $180.

My main point is all of this very technical talk about TIG and lanthanated tungsten and saving up $7-8k before getting into welding is going to scare more teams away than help them.

I see people spec’ing 200 amp welders, where you can make fine robot welds with the 125amp machine --even from Harbor freight for $119. Yes they’re not as good. You can plug into a 120VAC regular plug–which is huge advantage over 220 volt welders. There are no welds on a lightweight robot that require 200 amps. 140 amp is mostly used at half-power.

As for grinding welds, flux forms up on the outside of the weld, so you can chip it, but it always looks better to grind. Not worried about weakening them. I’ve yet to see a broken weld on a team 1108 steel weldment. Really.

Here’s our steel robot from this year. Completely welded by students.

#20

Have you ever tested that in a quantifiable way?

Perhaps. Although telling teams to get a $120 flux core welder might just as easily turn them off because of bad welding results.

Perhaps more importantly: flux core welding creates a whole host of additional health hazards not present with MIG welding. Is it cheaper? Probably. Is the savings worth risking my student’s health? Nope.

My impetus in suggesting a 200A+ welder is to enable welding of thicker sections of aluminum, which can be indispensable in some situations. The design flexibility is phenomenal. Being able to weld a large shaft collar into a sheet of aluminum is a great design trick that 95 has used for years, enabled by high-current AC welding.

Only working in steel can make pit re-work challenging because we’re not allowed to have spark-making processes. This part of the rules bums me out, and is a big deterrent to us using large steel components. Food for thought for those considering welding.

I’d believe that. A well-executed MIG or flux core weld can be strong.

I bet you could go to half the wall thickness in 4130 steel, keep a comparable strength, and save half of your frame weight. If this were to be TIG welded you’d avoid the health risks of flux and the time and potential structural weakening associated with grinding all the welds down.

My overall view of welding is this:

If you only want to work with 1-2 materials of limited thicknesses and value an easy-to-learn process: MIG is great. [While you can MIG a wide variety of materials, the setup, tear-down, and variety of consumables needed make the switch-over aggravating.]

If you want to work with any weldable material in a wide range of thicknesses and are willing to spend a little more time learning: TIG is the best bet.

1 Like