Welders help me out, test tomorrow!!!!!!

Today I completed the SMAW part of my welding qualification. Tomorrow is GMAW and I had the cl*** a year ago. The teacher confi****ed all our notes last semester as well and I can't remember the settings. I have to do a 3G and 4G (vertical/overhead) **** weld on 1/4" mild steel plate 8" long with 45 degree bevel with 1/8" land and 3/32" root opening. I planned on right around 17 volts and 170 fpm wire speed. Does this sound right? We're using Millermatic 1250 (I think that's the model number) 220V mig welders.

 

Lucky, these are just online refs, you CAN do it!

http://en.wikipedia.org/wiki/Gas_metal_arc_welding

www.millerwelds.com/______

 

Good luck! I know Punkabilly1306 speaks all that GMAWPAWTAWFLUXJAW welder jargon. Try him.

 

Thanks guys, what I'm trying to figure out is; do I have to make much of a voltage change between the root p*** and the cap? Can I leave it at 17.0 the whole way or do I have to heat it up a bit as I progress. We only get two shots at p***ing a bend test. Both of my stick welds p***ed first first try. I'd like to keep that streak going through the mig section.

 

I've been welding for 35 years and I couldn't tell you any settings I use for anything

 

Settings? I fire up a test panel, as soon as it's cooking, i'm welding. I'm like Kev, i really don't look anymore. Good luck!

 

how many p***es are you required to fill the area?

 

I've never done a certification test we're I wasn't able to run a couple of beads or practice plate first to get the machine setup right. I can't imagine they'd expect you to come in, turn the machine on and start right in on the test plate. If that's the case, I gotta wonder how knowledgeable the instructor is.

 

unless they are going to see if he uses the correct "formula" to figure out his wire speed and voltage, just to see if he can actually dial it in off of knowledge or just off of guessing

 

Some places want you to walk in and weld, no practice, it shows experience.

If I were you, I would practice a lot of different scenarios before taking that test, get a few settings in your head.... you should do fine.

GOOD LUCK!!!

 

To me that shows a lack of experience. How many professional welders do you know that go by a canned formula? Guess if the test is just to put down a decent looking bead, it doesn't really matter as long as you're close. If you're going to do a guided bend test or something like that, it doesn't make sense.

 

I guess I worded this wrong. What I'm really looking for from the experienced welder is, do you change the amperage much between the first p*** (root) and the final p*** (cap) I know a "one size fits all" setting is useless. I'll get time to practice as well. Just wondering how much of a change there is if any from start to finish. I am guessing three p***es to fill the void, four at the most.

 

That's why I asked the question. MIG welding was one of twelve modules I went through for this degree and it was quite a while ago and I don't have my notes to look at. At home I have a Hobart 175A 220 MIG welder but all I do with that is .095 wall roll cage tubing or .125 wall square ch***is tubing. Overhead and vertical welding of 1/4" plate is not something I do everyday. So you're right, I don't have much experience although I did get an A in the cl*** last year. I just wanted to know if I should be increasing amperage as I progressed through the weld.

 

Not 35 years here...but I was thinking the same thing!!!!!!!!!!!!

 

I would say YES, you would want to bump up the amps on each additional p***, because you are making the material thicker and you want a greater range of heat penetration. If you were to have your work ****yzed for heat penetration by a govt. inspector (cross cut inspection x-ray) they would want to see where you had an equal heat range throughout the entire weld.

AND to answer 392 Hemi: There are a lot of aerospace welders here in So Cal that can do some amazing welding by just walking up and not doing a practice run, they have that much experience. I have seen a welder do a TIG weld down inside a 2 inch valley with walls 3/8 apart and weld a perfect ss bead in there on top of a razor blade down in there without any arc penetration on the valley wall sides, it was extremely clean, it was later ****yzed and had zero defects or contamination.

 

My $.o2 is yes... heat it up a little and get the wire speed a little faster for overhead, on the vertical I'd say no... but it depends if your welding top to bottom,or bottom to top... if this makes any sense , I'm like the others ,do a practice bead and you will know.

 

thats me i retired 6 years ago from the union and welded my entire career. i have people ask me similar questions and all i can say is that every machine is different and youll just have to play with it to get it right. ive certified for lots of jobs and they will always let you use a piece of s**** to set your machine up on. if you want to have fun take a 6g pipe test to Alaskan pipeline specs, thats always a fun one to take. if they x-ray your test you need to watch out for porosity in the weld. migs are notorious about doing this.

 

HHRdave - TiG is very different from MiG, since you can make significant adjustments as you weld. The question has to do with MiG welding, so you're mixing apples and oranges.

Lucky77 - The last MiG certification I did was a 3G groove weld on 3/8" plate that was welded and tested on 9/18/07. The weld was done with a Millermatic 250, .030" ER70S-6 wire, 75/25 gas mix at 25 CFh, and machine settings at 19.5 volts and wire feed at 30. Weld was done in 5 p***es and p***ed AWS D1.1 guided bend test.

 

I'm glad to see this thread ! I've always wondered what the knobs were for on the front of my machine .

 

thanx for the interesting comments! my 1988 miller 200 [bought-new-well-used-since-then] has 5 pre-set amperage 'stops'.............i've never taken the time to 'investigate the amperage' they represent..... to my shame!
i'm gonna do the reading, of the manual, not for entertainment, but for an appreciation of the machine!
[after working afternoon shift, i 'wind-down' by doing jalopy journal---
the best time of my waking hours! again thanx for the comments on this subject!]
thanx red ryder

 

Thanks 392 Hemi, and thank you to everyone else. I forgot, I'm testing on 3/8" plate as well, not 1/4" like I mentioned earlier. Well I'll start out around 17A and bump it up to around 19A if it looks too cold. The test is moving bottom to top for vertical and back to front on overhead. I'm having lunch with fab32 before cl***, I'll pick his brain as well.

 

Is it a bend test? usually for Overhead you bump up the WIRE and go faster, not the heat. high heat and low wire is gonna leave a nasty burn on your wrist.

for what it's worth, i did my last Horizontal test at 30.5 volts and 450 fps wire on a brand new Miller. faster is ALWAYS better. HAZ is bad.

 

Yup, bend test. We cut two 1" wide strips horizontally across the plates that we just joined with a vertical weld. Both the root and the cap are ground off then one side from both strips is put in the bender. Turning the wirespeed up will also increase the heat if I remember correctly. I know I can cool it down or heat it up with arc length as well.

 

care full with that arc length thats where your porosity will come from

 

Yeah I know arc length is playing with fire, literally. I'm very familliar with MIG welding, just not overhead 3/8" thick plate. Thanks for all the tips, I think I'll do just fine.

 

That question is like trying to get an exact recipe of apple dumplins from my beloved grandmother.
I too have been welding for 35 years too and could never tell you the settings.
Just be patient and you will do well.

 

one of the biggest things that helps me lay down a nice bead is getting your face about 10 inches away from the weld to get in there and see exactly whats going on in your molten pool.

 

I'm not a welder and I DON'T play one on TV. I would however like to wish you good luck and ask you to lets us know how you did, good or bad.

Vance

 

Good luck to you on your testing! I did mine about 2 months ago for work. Been welding for about 8 years now and p***ed both 3g vert and 4g with no problems. I didn't change anything between my root, fill, and cap p***es. I ran My 3g vert at about 18 volts and on the WFS I had it at 2.25 on a dial that went from 0-10. I go back in this weekend to take the Stainless Steel 3g vert test. Again good luck!

 

Mostly I used to stick weld...w/Idiot rod. Lot of good points raised here, glad that Lucky gave some of the pros a chance to teach all of us.