Hold on the top for a slight second, but not on the bottom with a slight up and down. Do you pull or push? I use to do Us, but mostly do a straight zig zag for everything flat/horizontal. On vertical up I do a U still.

 

Pattern has little or nothing to do with it other than personal preference usually. You have to learn to read the puddle.

I often do a demo for students who are stuck on one particular pattern. I'll start doing a weld doing circles, then without stopping, transition to C's or Z's, and then finally again without stopping, transition over to a straight stringer with no motion at all. When I'm done most times you can't tell the difference in the weld except possibly a small hiccup where I changed motions and didn't get my hands set quite right immediately.

The reason I can do this is because I can read the puddle and manipulate it to get it to do what I want/need it to do. I'm not locked into a timing pattern doing the same motion repetitively. Timing patterns may work for perfect pieces, but you will crash and burn when you get to joints with poor fit up, changing gaps etc.

Undercut on laps is often due to bad gun angle. The fact you have better luck with circles tells me that part of your issue is that you aren't pausing to fill enough. Whether this is a solution to bad gun angle is tough to tell without picts and settings.

Personally on lap joints I find it easier to do C's or Z's vs circles. That's just what works easiest for me, though I can do them with a straight stringer or circles as well. I like to keep the main puddle down on the lower plate and use the motion to wash the puddle up onto the upper piece as needed. On 1/8" I usually watch the upper edge and move back down as soon as I see the edge start to want to melt. On thicker material like 3/8" that usually requires more than one pass, I treat it no different than I do a T joint.


Post up picts of your practice pieces along with machine used, wire size, gas and flow rate, material thickness and position ( if other than flat) and we'll help you get this down. It takes a while to learn to read the puddle. In the mean time most guys manage to get by on flat and horizontal with timing patterns until they get to vertical and are forced to learn to read the puddle. At least by that time they usually have gotten enough hood time to begin to have the needed references to begin to learn this. Good luck.

 

When building things I weld as straight and smooth as I can get it to lay down. I want the weld to look like a bead of caulk.All that dancing around and MIG like TIG just looks real cool.Sure. Sometimes you gotta weave to jump gaps because the fit up wasn't right or you're standing on your head in a corner fighting gravity. Learn to cut,fit and grind properly and that is seldom other than doing repair work, which I hate.

 

Awesome feedback. Thanks. Below is a recent practice run I made on a lap joint (ignore the other welds-those are pieces from when I first bought the welder). I find the most difficult part of lap joints is maintaining the edge. My welder is an Eastwood 175 (220V). The settings are not numbered by actual voltage and amp output but rather my heat is set at J (one step below max) and my wire is .035. My wire speed is set to 5.5 out of 10. My Argon/CO2 mix flow is around 25. View attachment uploadfromtaptalk1394208430234.jpg

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Also, I was always under the impression that some sort of motion was required to ensure proper penetration of both pieces. I always took great pains for some sort of motion, which in out of position welding brought on some ugly beads.

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Your bead is aimed too much on the upper piece if we are talking about the lap in the center not the fugly weld on the right side. I still don't know your thickness of material, so I can't make suggestions on settings. A maxed out 180 amp capable unit should do 1/4", so if this is around 3/16" or so, you may be a tad hot, but still doable. You might also need a bit less wire. It's tough to tell with out some reference to work with on size. What ever your top piece thickness is, that's what you are aiming for on your base leg.


Consistency looks decent for such a short weld, but you were a bit fast at the start. Top of the weld on the left looks consistent, but the bottom part below the tie in has issues. Weld across the top also looks like it needs work from what little I can see.


Assuming the settings are correct, you don't need any motion. However by doing so it often makes it much easier to control the puddle as you don't have to watch both sides at once. With this I'd aim a bit farther out on the lower piece than you are doing. I'd then use a C or Z shape motion to carry and wash the puddle up against the vertical piece and watch the top edge. As soon as I see the puddle reach that edge and possibly start to melt it, I'm swinging back down onto the base material again and watching it fill before repeating the cycle. The bottom piece usually takes care of itself, so I'm usually mostly concerned with the upper edge. You can do circles as well, but since I push solid wire mig and gas, the final part of the puddle is behind the arc and harder to see for me. I can do it no problem, but it requires a lot more concentration for me to do so, and honestly why bother if I don't have to?


Out of position welds I almost always use a motion. That's because I'm usually watching the edges of the puddle fill and it's easier to watch one side at a time vs trying to get my travel speed, heat and wire perfect. I have more control with a motion.


If you have examples of your undercut, post them up with settings. Same goes with your out of position welds. With those we can make some suggestions on what to do and how to correct your issues.

 

I really appreciate the detail. I am going to practice laps using the c and z motions and start further out. The undercut I was referring to was actually the center lap weld, where the edge is visible--perhaps undercut is the wrong terminology. With lap welds I was envisioning a smooth blend from the top piece to the base metal. The base was 1/8" thick, and the angle was 1/4"thick.


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Can you use paint or some program to mark what you are looking at. I think your terminology is wrong, or it's difficult to see what you are talking about in that picture possibly due to the angle.

Keep in mind with a filet weld or lap, the weld is only as strong as the thinner member. In this case the 1/8" base. More weld doesn't actually mean stronger. In this case 1/8" filet would be plenty, but it can be tough to do with larger wire like .035. 3/16" is a tad on the heavy side, and typically what I see students do when they are trying to do fillet welds on 1/8" with .035 wire at the tech school. 1/4" is over kill, but in some cases it can be just easier to run to a fixed point like the top edge of the angle. You do need to watch that you don't have too much heat and have undercutting issues on the lower plate however. With thin material like this, a small amount of undercut can be a large percentage of the base material. If that's the case, a large weld that causes you to undercut the lower piece is more damaging than anything else. Thick to thin can be a challenge at times. You need the heat to get decent fusion into the heavier material, but need to watch that you don't end up with undercut on the thinner piece.


Technically loosing the top edge of the upper piece in a lap joint on larger material is a "weld defect". You want to come in just under it. That's almost impossible to do however with small material and large wire. I like to just see the edge become round. If you stop before the end of the piece, the original edges and the weld line should line up almost exactly showing next to no loss of material at the edge.

 

I don't have access to my computer right now-I can when I get home. The lap I was referring to is the 2" bead dead center of the photo tying the right side of the angle to the bottom plate. I was worried that the top edge of the bead on the angle iron was unacceptable or would not be sufficient to tie the top to the bottom. Your bottom paragraph make sense for me to visualize. Is the short bead I ran too far into the top piece?


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Maybe these will help. Red line shows about where you should be max. A bit of rough editing may give you an approximate idea what I'm looking for, but I'd like the edge to be tighter than my pieced together pict shows. I just can't get the bead any closer to the edge and maintain the line of the original.

View attachment uplo.jpg

View attachment uploadfromtaptalk1394208430234.jpg

 

Okay. I see. So the goal is to not "bite" into the upper piece at all?

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Since typing out a bunch of words isn't one of the things I can do well, here's a link that might help describe what DSW is talkin about. Go to the linked page, scroll down to "Watch out for nothin' welds" and download that little pdf. On page 2, figure 2 shows a snapshot of what he's trying to get across. To take it a bit further you could mentally picture figure two with a variety of bead profiles. Kind of gives you a perspective to keep in mind when you're working on things.

http://www.jflf.org/papers/JFLF-Technical-Papers.aspx

 

If you want to refer to it that way. What you are doing is protecting the top edge. You still need enough power to get good fusion into the material on the upper piece. When you use the term "bite" I think of having enough fusion into the material, not protecting the top edge.

There can be a fine line when doing this, assuming the settings on the machine are correct. You do not want to turn down the machine to the point where you are not getting proper fusion just to protect the edge because you can't weld.

 

I checked out the document. It was definitely helpful. I did a few practice runs on lap welding with 1/4 inch. My better run was on C channel. I used a tighter Z motion and started the arc further away on the base. Below is the pic.
View attachment uploadfromtaptalk1394413133989.jpg

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Hard to get any detail in that picture. Bead looks like it might have used a bit more voltage to get the toes to wet in better especially at the bottom. A closer pict and settings would help.

Top edge from what I can see doesn't look too bad. Bead may be a bit large. Hard to tell size from that angle and distance. Remember you want the legs to be equal, so if the vertical piece is 1/4", you want the lower leg to be 1/4" as well so the reinforcement forms a 45 deg angle or just a bit on the convex side. You do not want a concave center as that is a weak point.

 

Looks like you are headed towards the right direction.... One tid bit that will help you out, when welding with solid (hard) wire clean your mill scale. it usually comes right off pretty quick with a flap or soft pad if you are worried about gouging the surface finish... Cored wires are a bit more forgiving toward scale.... hard wires not so much.... cleanup afterwards is usually a lot easier if you grind before also.

 

You're right. Before I did not grind the millscale until I made a post in this forum and others stressed the importance. In this case I forgot to grind this area.

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