Holes or not

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Hello GroupI am building a CNC machine and am having an odd problem with some welds. Some of the welds ( about 1/3 ) end up like the top one in the photo, both were done at the same time with the same gas, amps, feed, wire.... Both sound the same.I am in Australia and am using a 415v 3 phase machine, I tried increasing the gas flow from 15 ltr / min to 25 ltr / min, the porosity was still there but maybe not as bad ----- not sure about that last one though.Any suggestions, Attached Images
Reply:There's any number of things.Breeze blowing in the door, bit of oil on the tubing that just vaporized due tot he heat of the previous weld, nozzle has a bit of spatter stuck in it, if it's the last weld on a joint it could be the internal pressure in the tube blowing out, bit too steep of an angle on the torch sucking air underneath, diffuser holes getting plugged.On the last idea I use a miller 350P at work with the centerfire tip/nozzle arrangement, a great idea except for one thing. The diffuser holes get plugged real easy and it'll do exactly what you're showing in your pic. As hard as it is to believe out of a dozen or so holes in the diffuser if one gets plugged it'll screw up the weld....Mike**EDIT**just noticed the paint, that could be a prob too
Reply:yeah, I was looking at the paint too, that would definitely cause a problem.HH187Hobart 500i plasma cutterClark 4.5" GrinderDewalt 14" chop saw30 gallom 1.6 hp compressor10 gallon pressure pot sand blasterlots of hand tools
Reply:Grind off the paint around the area to be welded.  Mig and tig don't like impurities in the weld.  Stick and fluxcore are a little more forgiving on uncleanliness of the metal but you should still try to clean up your metal as best you can.  This goes for paint, grease, rust and mill scale.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Hello Group and repliers, The torch is new and was installed without checking, this might have something to do with the problem!!  no broken bits in the bag, to be fair, when I told the supplier today they are sending me two without cost.Thanks for the suggestions to.Ed Attached Images
Reply:Originally Posted by weldappiHello Group and repliers, The torch is new and was installed without checking, this might have something to do with the problem!!  no broken bits in the bag, to be fair, when I told the supplier today they are sending me two without cost.Thanks for the suggestions to.Ed
Reply:Ya know................I'm not sure it's "porosity"On a butt joint with tubing, where the square butt meets the curved shoulder of the other piece, there's a fairly wide and deep gap.  Filler tends to want to drop into the gap instead of building a bridge to fill the gap.  While it ain't the Grand Canyon, it is a fairly wide gap with no bottomYour puddle may look allright as your welding, but the molten metal sinks into the gap and you have voids such as in your pic.On this type of joint slow your travel speed, add more than necessary filler (or what you'd normally think is a necessary amount), and massage the puddle to build back over what you just deposited.  Because you're slowing your travel, there will be a tendancy to burn thru the thin edge of the butt, a little (and I mean a little) whip or weave will help to move the heat around to prevent this, while at the same time building the "bridge"/"cap"The purists may cry, pizz, and moan, about this technique..........but it works, and you have a nice sound joint Attached Images"Any day above ground is a good day"http://www.farmersamm.com/
Reply:I might be in total agreement with Samm. This particular gap needs a good bit of filler to really cover it. Usually I will do 2 passes on these types of tube welds. A first pass laid into the open root; many times the first pass won't even close the 2 pieces of metal together, but it is just a landing for the next pass. Then, the 2nd pass is a full, wide bead. The other thought is to drill a hole in the tube so you have no gas blowout.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:The torch looks like a Binzel copy, from China.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT