Rookie welder needs help

[SLP82]

Hey guys... I recently graduated from a welding school that was basically a "crash course" consolidated into a short amount of time. I was then lucky enough to land a good job building trailers. When the owner gave me a weld test, it was 1/4" thick steel square tubing and I welded it perfectly. Then today I was building the gate to a trailer and it was made from 1/8th inch thick smaller square tubing. As soon as I went to lay a bead, it burned through. I grabbed some scrap tubing same size and thickness, and tried practicing on it, kept burning through. Only way to not burn through is to move excessively fast... but the weld then looks like crap. This machine is a Millermatic 210. I set the voltage to "3". Any lower and it would not even arc. The wire speed was about half way between lowest and highest setting. The only way I eventually was able to weld the gate up was by welding about 3/8" area at a time, almost like large tacks, then let it cool for 1 second and hit it again, and repeat. This kept it from blowing through. My boss said he "thinks" the previous welder before me could weld it straight through and not have to do small areas and allow it to cool. Does anyone have any recommendations? Thanks!

[OctoberSnow]

just practice, tweak the amps and the wire speed and keep moving. you didn't mention what wire you are using, I will guess .035 .. good fitting helps and adjusting hood shade so you can see your work well helps too .. after a spell you should have no trouble with the 1/8" stock.

[Boomer63]

As October Snow said, keep moving! You will not have to build a puddle, just get your arc going and move! DON'T be afraid to stop if you feel like you are about to burn through. What position are you in? Flat?

[SLP82]

Vertical and flat... not sure of the wire size. What movement technique should I use to keep the weld looking good? Going forward then backing up slightly causes burn through. Is there a technique that will still look good but be less likely to burn through? Also wire speed was at 55. I checked today. I'm still having to do a series of weld for 1 second, stop for half a second, weld for one second, stop for half a second. This has given good results and appears to "stack dimes" on the weld.

[H80N]

A Lot of useful MIG info for you here................. sounds like you could use the basics & refenece materials

https://www.millerwelds.com/resources/welding-resources/mig-welding-resources

[SLP82]

Thank you for that link, it actually helped some. I'm starting to think that maybe my boss may not have the correct wire or wire thickness for the application he is having me weld. This may not seem likely, but he is not a welder and can't tell me anything about the welder, wire type, etc. Also I'm going to double check, but this shop is very small, and he cuts corners to save money, so I wouldn't be suprised if he is running straight co2 on the welder. Until you sent me that link, I didn't even know you can do that. Also the material I am welding, he told me not to wire brush or grind because it doesn't need to be, and some of this steel seems to have a coating on it. This obviously goes against what I was taught, but he doesn't want me "wasting time" prepping every weld. According to that link you sent, there is certain wire that should be used for dirty metal. What caught my attention was it said for economical welding, use a different wire than the wire designed for dirty welding. Again, to keep cost down, I suspect he is loading the machine with the economical type wire that is not designed for welding dirty material but having me do it anyways. Obviously there is some exact specifications of this welder that I need to find out to better understand what is possibly going on here. Thank you again.

[H80N]

Thank you for that link, it actually helped some. I'm starting to think that maybe my boss may not have the correct wire or wire thickness for the application he is having me weld. This may not seem likely, but he is not a welder and can't tell me anything about the welder, wire type, etc. Also I'm going to double check, but this shop is very small, and he cuts corners to save money, so I wouldn't be suprised if he is running straight co2 on the welder. Until you sent me that link, I didn't even know you can do that. Also the material I am welding, he told me not to wire brush or grind because it doesn't need to be, and some of this steel seems to have a coating on it. This obviously goes against what I was taught, but he doesn't want me "wasting time" prepping every weld. According to that link you sent, there is certain wire that should be used for dirty metal. What caught my attention was it said for economical welding, use a different wire than the wire designed for dirty welding. Again, to keep cost down, I suspect he is loading the machine with the economical type wire that is not designed for welding dirty material but having me do it anyways. Obviously there is some exact specifications of this welder that I need to find out to better understand what is possibly going on here. Thank you again.

NOTHING the matter with straight CO2 for this application.....

Flnd out which wire thickness & alloy you running and set parameters accordingly .... to get in the neighborhood.... adjust from there

MIG is very versatile and forgiving..... BUT....

you must remember that operator technique & speed are MAJOR factors.... that is why there is so much variability in settings

what brand and model welder & feeder............????????????

[Olivero]

Building trailers but don't waste your time prepping the weld? I am sure he won't admit to saying that if one of them splits in half on the highway after a couple of bumps. Crazy what some people will do to save money. MIG is extremely forgiving but when I run stick, if its 7018 or 6010 I still wire brush my welds, just makes me sleep better at night knowing I did everything I could to make that weld come out on top and I don't have to worry about it breaking apart.

Proper prep and procedure is what sets apart the rookie and the professional. If its a hobby type job, like a fence for your garden or something you will be using and you are the one getting hurt if it fails then fine but other people are involved. I would prep the joint either way, not worth the hazard if you don't. Since you are burning through I imagine your penetration is definetley good enough but that's just a procedure and setup point I believe more than a cleaning point but in general, the area to be welded should be free of oils and contaminants like paints and coatings.