Hello All,
Something I may not have mentioned before
I'm a Qualified weld inspector, I used to fabricate as a really serious hobby and ended up in a job that was very reliant on welding repairs to steam pipework, anyhow I went to college and got qualified as a Radiographer (X Ray guy) and Weld inspector, While I was at it I did tests and Qualified in MIG, TIG, Stick and Oxy/Fuelgas Welding.
Anyway, I'm not bragging but welding is one of my favourite things, If anyone out there has a question I will gladly provide what knowledge I have, I have read through this whole thread and spotted a few areas where help might be welcome so here goes;
Someone mentioned a problem with Chinese welding wire, specifically that it welded OK for a few seconds then started to spit and play up then went back to welding OK.
This isn't just a problem with Chinese wire, what it is, is rusty wire, the rust is so fine that it doesn't show on the copper colour, the problem is intermittent because the rust only happens on the top of the roll when condensation settles on it, or if there is a hole in the plastic shrink wrap, often an early indication of the same problem is a regular pinhole every inch or two along a consistent weld, a small amount of rust breaks down to form gases and this pops a little bubble into the weld. The fix, either throw away the wire, or cheaper still, wind off the top two layers of wire, this is not a waste, the wire is useless and will cost you more in gas, time and spoiled welds if you try to use it, use a clean white rag to and run the wire across this to see if you are down to clean wire.
Incidentally, if you run rusty wire for too long you will need to change your liner as it will get contaminated, this will just make everything harder and is often the reason that folks starting with second hand machines give up on MIG,
I think ED asked about the welding two round tubes together at right angles, welding over the gap will increase blow holes but there is an easy way to create accurate copes (that's the proper name for the fish-mouth shape on the end of the tube) use a bi-metal hole-saw blade that matches the size of the tube that you need to weld to, mount that hole-saw on an arbor, either in a fixture, a Milling machine or even a heavy duty drill press, using half of the normal cutting speed and very slow feed the hole-saw will cut the perfect cope every time just clamp a good vise down to the table in the right location to centre the saw to the tube, angles are also easy to achieve, just angle the tube relative to the hole-saw. An old school alternative is to hammer the side tube flat, that way you end up with two fillets one either side of the pipe welded along the centreline of the long pipe, it is actually a very suitable method in many cases.
DaveH asked where to point the wire, I think he meant when welding the open end of a box section to the side of a box section of the same size,
The answer here is to point the wire mostly at the radius of the side of the box section and set your welder to build a little more bead than you would normally use on a butt weld, as the bead grows it will "catch" the edge of the open end of the other tube, at this point slowly move along while maintaining your torch at the same angle, as the weld will catch the full width of the open end you will achieve full penetration without blowing through.
There have been quite a lot of discussions over the years about why anyone bothers with Flux cored wire, To be frank, I don't know any professional welder that would be caught dead using it, except in MIG hard-facing applications where the flux adds alloying elements to the weld pool, Otherwise I'd give it a miss, the reason the finish is always horrible is that hobby machines rarely have the energy to allow a pool big enough to let the flux flow from the inside to the outside, it's like trying to weld over a constant flux inclusion, YUK, The professionals use magnetic wind guards if they have to MIG or TIG in wind and if they cant get a gas bottle to the weld they mostly use a stick welder, as for hard facing the benefit of flux core is that the flux which is particularly moisture sensitive is kept dry inside the wire and the welding machines are usually pretty gutsy so have no problem supplying the heat required to minimise inclusions. Some hard-facing stick electrodes use flux cores to keep the flux dry as well, they are useful but horrible to use.
I know I read someone say something like; I'd rather have a rough looking weld that holds rather that a pretty weld that doesn't.
With Respect guys, in the Weld inspection game, Most guys agree that; "If it looks good it probably is good"
Now, I couldn't tell you how many weld X Rays I've seen over the years, but I can say that at one point it was twenty five yards a day six days a week for six or so months and that was just one furnace build. In all these years I have seen lots of welds that look great on the outside and have hidden defects, from Professional welders maybe 5% of all welds have more than 3 defects per foot, which is a fail in most industries, BUT, (and I did that in but Capitals for a reason) 99% of welds that look rough on the outside have more than 3 defects per foot, So if you go with; "if it looks bad, stop, clean, adjust and try again" you will really learn how to weld properly and it won't take all that long and while you are learning the welds will be better quality than if you just "soldier on", while it gets the job done, the job never looks right and you don't learn much because you never get to find the solution.
Sorry If I've sounded a bit harsh here guys, but I have tried to take on the whole thread in one post,
One last point too, the settings that work for one guy won't necessarily work for another, even on the same machine, job and consumables most professionals will tweak the dials.
Just try and have fun, with a little patience and practice almost anyone can weld well, The formula is as follows;
Trouble = Stop + clean + adjust + try again = Success
Making Good welds is always more fun than struggling with bad ones
Best Regards
Rick
Whatever it is, do it today, Tomorrow may not be an option and regret outlasts fatigue.