How much penetration it too much and how much is too little?
By too much I mean should you see any weld coming through the other side of the material you are welding on?
By too little I would think the joint should not be depending on the filler material to hold it together. This would pretty much indicate lack of amps or a weld sitting on top of the metal.
I just finished practicing on a peice of the ever popular bed frame. This stuff is 1/8 inch thick. I made a box section out of 2 "L" pieces and ran the bead on the outside edges. After the weld I cut it in half at a random section and then polished the cut until I could see the weld well enough to distinguish the bead and the seam of where both pieces of frame were clamped together. I notice only about 1/32 penetration. I did not see a --O-- but more of a __o__ without such a raised bead, limited ascii art here. In other words, I can plainly see the seam on the other side of the welded area with no filler showing .
I am using an old Craftsman 110volt buzzbox set at 45 or 50 amps and am using Weldit 5/64 6013 rods. Good ground and pretty darn clean metal, I sanded it well before welding. I do have to say that I really like the Weldit 5/64 6013 rods over the Lincoln brand 1/16 6013 rods. I had sticking troubles with the Lincoln rods and the Weldit rods are pretty much a dream with very nice beads with very little sticking and the slag falls off with a little whack of the chipping hammer.
So, should I be seeing filler metal on the other side of the weld? How much penetration is enough and how much is too little?
This "penetration" thing makes my blood boil. If you really want penetration into a weld joint you must bevel the edges. There are some extreme situations where the weld bead sitting proud is the only source of strength. When you made your "box section" the corners should have been tacked together so that there was an open corner or natural Vee preparation. For this application a full penetration, full strength weld is really not necessary if the box is being used a structural member. You could have stitch welded it. Remember too that the weld metal is frequently far superior to the parent metal. Randy
I think I know what you mean, but what else will hold the joint together other than the filler material? Certainly you do not want a cold lapped joint, but as long as the filler really is fused into the base metal, then in one sense it doesn't matter how much penetration you have achieved--whether you have a fusion zone that is 1/64" thick or 1/32" thick is irrelevant, since the filler and the base metal have fused into one. (I speak from the hobbiest perspective--I am sure that it does matter in terms of how large the HAZ is when using certain kinds of metal in critical applications!) What DOES matter, even for the hobbiest, is the geometry of the resulting joint: Do you have a joint with a small area of fusion -- perhaps just a thin layer of filler material fused over the top -- or do you have a joint with a larger area of fusion, where there is fusion from base material to filler to base material part of the way or all the way through the thickness of the pieces being welded?
To say this another way, when you finish the weld, what is the thickness of continuous metal (base metal-fusion-filler-fusion-base metal) that you have produced? It really doesn't matter how "deep" the fusion is, as long as you have produced a sufficiently thick area or cross-section where there is continuity from base metal to filler to base metal. However, if you have fused only a small width of material together -- perhaps a big bead sitting up on top of the joint, with only a very narrow cross section that is actually fused into the base metal -- then you have problems.
Note that you may not need any more strength than is provided by a good bead that only extends a little way into the thickness of the joint. This is the classic picture that you see in the manual that comes with your welder, showing a flattened oval of weldment, with half of the oval above the surface and half below. (I think this is the picture you had in mind with your first ascii drawing above.) Note that in this situation, you will most certainly still see the seam on the other side--and that's okay, if the bead provides enough strength for the needs of the project. On the other hand, your second drawing suggests that you may be getting a very small cross-section where there is fusion from base to bead to base; in this case you do need to increase your heat (amps)--more about that below.
However, if you need to get the weld *all* the way through the thickness, you will achieve that less by cranking up the amps, and more by how you prepare the weld and the procedure you follow. If you butt two square edges together, you will not weld all the way through without cranking the amps way, way, way up (with the resulting likelihood of ugly burn-through, increased warping, etc.). On the other hand, if you bevel the edges and leave a small gap between the pieces, you can produce a weld that goes all the way through the thickness quite easily. You may need to make more than one pass, of course, but on each pass the penetration (the depth of fusion between base metal and filler) does not need to be all that great, so long as there is fusion at every point where filler meets base metal.
On 1/8" material, using a 110v buzzbox, you are probably going to be much happier with the results if you get the amps up around 85-100 (use a 3/32" 6013 rod). 45-50 amps seems way too low for 1/8" thick metal; in fact, 1/8" thick metal is probably the realistic upper limit for a 110v buzzbox, so you ought to be running it close to its maximum setting. (You can do thicker material, but then you will HAVE to engineer the joint--bevel the edges, etc.) Note that you need more amps for an inside fillet (corner) weld, and fewer for an outside corner. Note also that the amps setting for a 110v buzzbox may not be equivalent to the same amps setting for a larger, 220v welder -- or at least, that has been my experience in switching from the 110v buzzbox that I started with, to the 220v monster that I now have. The 110v buzzbox just doesn't have the "oomph" that the larger welders have.
The difference may be less due to the brand, and more due to the size. I find 1/16" rods to be a colossal pain to use -- when you use a lower amperage (25-35), it is extremely hard to get them to strike, and hard to keep from sticking or going out because you don't have a lot of arc length to work with at that low an amperage. If you run them hot enough to keep the arc going easily (45-55 amps), they start turning bright red about half-way through!
Depends on the joint. For a single-vee with an open root, yes you should see some. For a square-groove with no root, probably not.
I think that you mean that it should not be depending on reinforcing; the portion of the weld bead above the adjacent base metal. This, for the most part, is true. If you had nothing but reinforcing (cold bead stuck to the top) you'd be in trouble. Remember, with welds, strength is directly proportional to the throat - the thinnest cross section that carries load.
Did you leave a root opening? That would probably help.
Once again, it depends on the joint. For strength purposes, the outside of the 'beam' matters much, much more than the inside, so not having full penetration probably isn't a problem.