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Post by kwrangln on Mar 17, 2006 21:39:23 GMT -5
Chuck, it would be a better process if you doubled your root gap. Rule of thumb, gap should be equal to the toe. Tack only the ends of the piece, use a backing strip or plate at the ends to hold things in alignment. If you feel the puddle is falling through the gap too much, use a copper backing strip made from a copper plumbing pipe slit long wise and pounded flat. Keep the heat up on your welder, and continuous stringers so you dont have the cold starts. increase travel speed a bit, you hit on this already on not traveling slower to get more penetration, now speed it up. First pass should just fill the root, not actually start filling in the bevel. Second pass should not leave a deep gap to fill like yours showed. With the capacity of the welders in question, it should ideally take about 6-7 passes to completely fill the root and bevel from one side, which will leave the weld standing proud of the base metal. For testing purposes, we ground the weld that was proud of the base metal to 1/16" above the base metal, but it wil be ok grinding it flush for our applications. Like I said before, every cold start is a weak point. While doing my test tickets, if you stopped a weld in the plate, you might as well throw it away, it wont pass. Good job with the pics, and a good beginners write up, but still there are improvements to be made. Dont take this the wrong way, not knocking your work and I'm pretty sure it will hold up, but for the sake of helping others...
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Post by What It Was on Mar 18, 2006 9:25:12 GMT -5
Wow... Now I can confidently say that "if somebody can't learn from this thread with all of the knowledge that's here... then they must be a rock" ;D
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Post by Chuck on Mar 30, 2006 15:34:10 GMT -5
Believe me, I posted that set hoping to get some more tips from the more experienced weldors here. ;D I did realize after the root pass that I really needed a little more gap, but I hadn't had time to play with it since, and didn't know how much. I'd start to get better penetration once I got about an inch and a half into each run, that's why I ended up having to come back and V the backside -- too many cold starts. So far I seem to get my best penetration running at about 18-20" a minute or so. I ran a little slower on the plate in the last set of pics and you can see it piling up too much in the photos. I do have a shot of one of the fillets I ran on the bumper -- weld across the top is a single beveled pass (not as much strength required there for the length), but the vertical fillet shown was about three passes at 18-20" per. I haven't had a chance yet to get any of my more experienced friends to look at it up close, though. Any thoughts, if you can see enough to tell anything? One trick I've been using when I'm trying to get my travel speed consistent was to mark off (near enough to the weld that I can see it in the light from the arc) at 1" intervals with soapstone. That way I could count one-two-three seconds per inch. In fact, you can still see a few of my marks to the left of the vertical weld in the pic above. Helped a lot, and that's how I got the more consistent bead and travel speed on the runs above ... still a lot to be gained, though. One more question I've gotten mixed response on -- if you're running beads on a short-arc gas shielded box like this with a section this big, do you weave at all? I seem to have had better luck running dead straight and fast, like in the photos just above, particularly if I can get the work into a flat position. I tried a couple of variations of pattern on a couple of less critical fillets, and you get something that looks pretty to someone who doesn't really know either way, but I doubt I'm getting much penetration on it. Incidentally, I'm not particularly worried about the weld in the V at the end of these plates shown, that weld has almost no stress on it. The long, straight fillet in the second pic (a close up of the top fillet in the first) gets all the stress, so that's where I'm most concerned with quality ... Thoughts, opinions, and experience always welcome, it's a lot harder to learn if you don't usually have experienced folks around to ask if what you're doing is good, so it's made things a bit more challenging.
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Post by N2Rocks on Mar 30, 2006 18:56:59 GMT -5
I suggest you make a weld on a couple pieces of scrap that you can try to break. Try about half an inch bead which should be strong enough to hold. Your weld could look good but will snap right off one of the pieces if you don't get good penetration. The pics may look ok, but even my MIG warns against trying to weld pieces too large and states they'll look good be possibly fail.
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Post by PaulC on Mar 30, 2006 22:21:41 GMT -5
Looks like your not getting alot of penetration. See how it is piling up in the center, and not a smooth transition to both pieces of metal. The indent along both sides of the weld is a weak area. Try weaving it more and spending a little time on the vertical piece and then come down to the bottom piece wait a little and then repeat. Just like Don said it you welded some scrap together like you did on your recovery brakcets the weld would break along the creases.
PaulC
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Post by kwrangln on Mar 31, 2006 21:23:34 GMT -5
In this pic, it should definatly have been a multi pass operation. Keep the heat up and wire speed down as low as possible, just high enough to maintain the arc. Your not looking for deposition, your looking for heat. As Paul mentioned, the toes of the weld are not flowing into the base metal, while the center of the bead is crowned almost to the point of being a peak, a sure sign of too low on the heat, too high on wire speed. Excuse the ms paint drawings, but here's how I would have approached that joint with a less capable welder. The first pass would serve two purposes, its starting to fill things in, but its supplying heat that will be needed for the next two passes to get enough penetration. Make the welds as continuous stringers, get away from all the cold starts, they are a bad thing. Make the second and third passes pretty quick after each other, just long enough to clean things off between passes, you want to keep the base metal warm. Try it out on a few scrap pieces and post up how it turns out.
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Post by Chuck on Apr 2, 2006 9:57:20 GMT -5
Good deal, I should hopefully have a chance to work on it some this afternoon (if I get my butt off here! ;D ). I have some more work to do on the plate pictured in the first set, in this case filleting on a reinforcing flange, and if all goes well getting it welded up where it needs to be on the bumper. This piece (unlike the endplate pictured above) will actually be fairly strength critical, hence part of the reason I was looking for advice. I'll get some pics, and hopefully be back on here later tonight looking for more checks. ;D We've got a good arc welder with more than enough capacity to do these welds single pass, but frankly my arc welding sucks -- right now I'm trying to actually get fairly decent with one process before I try and start switching around. That probably means if I can get my more critical MIG beads looking better, you guys will get to look at my ugly stick work, too. Thanks again for the great input!
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Post by Chuck on Apr 2, 2006 19:28:45 GMT -5
Alright, a few fresh shots. I got a reinforcement welded onto the bottom of the winch plate, and ran four passes for most of it. It was a 30" strip, and I did my darnedest to run each pass nonstop, but the nice new 20A breaker I'm running this box on still likes to trip sometimes after about 20" at full output. Material is an L2x2x1/8", fillet to a PL1/4". Root pass: Three top passes: Got a little porosity right at the end of the last long pass. End plate weld, which is actually not very critical, is three passes. When the time came to weld this in place to the bumper, I came to the conclusion I should really stop screwing around with the little box and break out the big one. My SMAW isn't particularly good, but I figured I had better odds of getting a good, solid weld, and I could always grind it out and do it over. Actually came out a little better than I'd expected, since I switched over from 6011 to 6013 ... huge difference there. Material is aforementioned PL1/4" to HSS6x4x3/16". Cleaned and about to be clamped in place: I went ahead and chipped the pass from the first rod all the way down so I could see whether I was getting complete crap. Looked a little better on the start than I'd expected, actually. Completed the first pass, chipped and cleaned it all, and ground out the two spots I'd screwed up. Then ran a second pass down most of it, because I'd actually been hot enough to undercut on the plate (which is about 1/16" higher than the HSS tube): Next weekend I'll be removing the whole assembly so I can fillet the backside. Meanwhile, I'm even less experienced with arc than I am with MIG, so comments and suggestions are more than welcome. ;D
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Post by PaulC on Apr 2, 2006 20:45:53 GMT -5
The 2nd picture from the bottom in the center of the weld looks good. Uniform width. That is what you should try and get. Try some 7018 rods. Less splatter and less clean up.
PaulC
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Post by What It Was on Apr 2, 2006 22:04:29 GMT -5
Hey man... that's looking good!
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Post by Chuck on Apr 3, 2006 10:29:27 GMT -5
Will do. I'm just about out of 6013 anyway, so I'll pick up some 7018 tonight. From what I've read 6010 and 6011 have better penetration -- would it be worthwhile to run a good root bead with 6010 or 6011 to make sure I've got good penetration from both sides, then clean up and complete the fillet with a pass of 7018?
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Post by N2Rocks on Apr 3, 2006 20:56:35 GMT -5
I'm glad to see you switching to the arc welder. I normall use 6013 or 7018. I normally don't use 6011 which are best for dirty/rusty metal or cutting. Although 7018 rods are stronger (70,000 psi vs 60,000), they normally require slightly higher current and can be a little more difficult to work with, especially if you normally have difficulty getting the arc started. They are my favorite rod for high strength requirements.
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Post by Chuck on Apr 4, 2006 10:04:03 GMT -5
Well, the machine I'm using won't have trouble with the current requirement (100% duty cycle up to 200A, and right now I don't forsee ever needing even that much current), so it's just a matter of practice more than anything. I count only sticking the rod once on a start and only having to grind out 6" worth of a 37" bead as an accomplishment considering my personal level of skill (or lack thereof), so it's a good motivator to practice and get a little better. ::grins:: Fortunately it's pretty easy to pull the bumper and flip it to any orientation I need, so being able to do all the work on it flat makes a big difference. It was about 85lb before the winch plate, so it's getting fairly hefty and awkward, but certainly not enough to be a problem.
One thing I was reading last night, back on the subject of the little MIG box ... I hadn't been clear on the relationship between wire feed speed and current. Now that I've found a couple of better references I feel like it almost should've been obvious that current increases with wire feed speed given a constant voltage, I guess that's just a Homer Simpson moment. Doh! I know that box will put out 130A (at a whopping 10% duty cycle) if I get it set right and fix my technique -- crank up the w.f.s. and move a LOT faster. I was only running about 110A on the stick weld pictured above, so once I'm done running critical welds for a while, I may go back to playing around with scraps of plate and the MIG box to see what I can get out of it. I'm going to be using it extensively when I build the frame for the bed, which will probably all be in the 16ga to 1/8" range max, so anything I can do to improve my techniques and understanding there will be a help.
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Post by What It Was on May 6, 2006 16:46:20 GMT -5
Well, I finally got my Lincoln 225 Amp stick welder up and running.. Layed down some ugly a$$ beads with 6011 rods... (Which In my opinion Suck)... I was welding on the new used frame and my outboard leaf kit... I welded both sides... I had good penetration... So I have no doubt that it'll hold up... The welds aren't the prettiest but... It's Jeep to beat on... So, they'll serve their purpose in due time.
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bophi
New Member
Posts: 6
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Post by bophi on Sept 11, 2007 19:06:35 GMT -5
n2rocks, you are correct. i never heat metal for welding unless it calls to be heated, which most metal don't. for higer amperage use a smaller rod , lower apg. use a bigger rod. when you cannot adjust the amperage. mig welding is for thin sheet metal . i'm a tig welder. i hope this info helps...... bobby
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