weld penetration

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i did some today with my old arc welder here are photos if you know any info bout it http://members7.clubphoto.com/geoff1...ner-6a6b.phtml now anyway i got 3 different size electrodes from left to right its a 3mm electrode the one in the middle is another 3mm but silly me the flux is a smaller size and i thought it was a diferent sized electrode. the one on the far right is a 2mm electrode. then i did 3 beads all about 15mm long and the cut it through the weld with a hacksaw. but from this photo (not very good quality) you can see that you can only see the cuts from the hacksaw and no visable weld penetration how do i cut it so i can see penetration http://members7.clubphoto.com/geoff1...ner-6a6b.phtml also what do the numbers mean on the electrode
Reply:Try this site at Lincoln:http://www.lincolnelectric.com/knowl...sification.aspI did a search on their site for "electrode numbers".To see the actual amount of penetration there are acid etchants that will show the parent metal distinctly from the weld bead.  It is hard to see the demarcation otherwise.
Reply:The site mentioned by "lotechman" is a very usefull one.There are 2 main factors affecting weld penetration:1- Type of current being used (AC, DC+ or DC-). Note DC- Gives deeper penetration that AC and DC+, as ellectrons are transmitted from the tip of the electrode to the workpiece and therefore more concentration of heat on the worpiece.2- Type of coating (i.e. Cellolesic type electrodes generate more H2 and therfore more heat onto the worpiece.)Regards.Zaher
Reply:Geoff 390You asked"how do i cut it so i can see penetration ?"It's not a matter of cutting , but of smoothing the cut edge metal and etching it with an acid. Belt sand using maybe 80 grit first and  then hand polish up with wet and dry paper to a mirror finish.Its been years since I have done any and can't remember  for the life of me,what the acid was. Possibly hydrochloric or muriatic but not raw.Wear appropriate eye protection.Grahame
Reply:Not sure if this will help, but if you want to insure complete penetration, bevel your material, turn the heat down a bit and use multiple passes.  also, if you're just looking for penetration, turn the piece over, and look at the stripe of discoloration, usually dark blue.  if it's atleast as wide as the surface bead, penetration is pretty good.  And, if you have a press, you can grind the bead smooth, and bend it outward, and see if it cracks or has porosity in it.  Hope this helps.
Reply:thanks for  your responses the only thing i can adjust on my welder if the electrode lead which can be pluged in the 12 gauge slot or 10 gauge it presently is in the 12 gauge ill have a look at the colouration on the other side
Reply:In the labs both at school and at work we do all our etching with nitric acid.At work we only do macro-etching so the only surface prep we do is to get it somewhat shiny with a flap-wheel (80 grit, IIRC). The etchant we use is 70% nitric acid - 30% water. We put the acid on for about 3 seconds (acid turns brownish-black), then dunk in a big bucket of water, then dry off with compressed air (don't try to wipe it with anything or you'll smudge the etch).At school we mainly do micro-etching (etchings that will be examined under a microscope) so the surface prep involves lapping the surface to be etched with progressively finer wet sandpaper (from 220 down to 1000 grit) until the surface is perfectly flat, smooth, scratch-free, and almost mirror-like. Finally we polish on a polishing wheel to get a mirror finish. We do the etching with 30% nitric acid - 70% water (lower acid percent slows down the etching so it's easier to stop it at just the right moment), then rinse with water in a sink to stop the reaction, then rinse with alcohol (70% rubbing alcohol will work fine) to get rid of the water, and finally dry with a heat gun/hair dryer.For what you want to do, just macro-etching should work fine.As far as finding nitric acid... well, I'm going to guess from your use of millimeters that you're in the UK. The good news is that it's apparently easier to find nitric acid in the UK than in the US (don't know why). Assuming it's not available in any hardware stores and you can't find a chemistry supplier, try looking for a store that sells stuff for hydroponics (it's used as "pH minus" or "pH down" to increase the acidity of the growing solution).As always, when working with acids use gloves, proper safety equipment, yadda, yadda, yadda...Visit Tensaiteki.com
Reply:I've cut pieces into and used a DA sander to see the penetration.DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:I use a stress relieving technique and a hammer to see penetration,...you dont see much of it thou, but you know if you had enoughMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!