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  1. #16
    Join Date
    Feb 2009
    Location
    moonbi nsw Aus
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    64
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    288

    Default

    Thanks for kicking off this thread Grahame and getting this information for us.
    I had attempted to weld a bit of mild rod to the end of a drill bit to give me more length. Invariably it would break at the weld and had been a futile effort. I asked a fitter machinist once what he does and he said to use Stainless Steel electrodes.....guess what.....worked a treat. It is such a nice material to weld with too. I bought a small package (10 rods, I think) just for "stock" when I need to extend a drill bit
    Just do it!

    Kind regards Rod

  2. #17
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    1,034

    Default slag inclusion

    Keep an eye on the slag pool behind the rod/arc, if it has red streaks spinning around chaotically you will be getting slag inclusion.
    Stop, chip it or grind the slag out, maybe a few more amps.
    Cheers, shed

  3. #18
    Join Date
    Feb 2009
    Location
    moonbi nsw Aus
    Age
    64
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    288

    Default

    A mate showed me the basics of welding 40 years ago. HE was extremely critical of my results and this made me look hard at my results as well. Even now, I will do a weld and examine it to make sure it is "right". I often have to grind back and go again. I made a frame for a 20 tonne hydraulic jack out of 150 X 75 mm channel. Once tacked up and with high amps it was a lot of fun feeding in the electrode and making big welds. Thinner stuff always needs a lot of care as you are welding it
    Just do it!

    Kind regards Rod

  4. #19
    Join Date
    Jul 2013
    Location
    nsw
    Posts
    256

    Default

    sitting down on the job really helps with comfort and stability whilst welding, plus try and prop yourself against something solid.

    run some practice moves to make sure you have the reach to complete the weld.

    try welding on some scrap material before you totally butcher your important welds and get discouraged.

    remember the performance of one welding machine might differ slightly from another depending on electrical supply, length of leads and general manufacturing variables.

    look for guidelines and parameters on each rod manufacturers packaging for amperage guidelines, but be prepared to adjust for your conditions and thickness of steel.

    i remember reading somewhere an old timer telling a new welder ( without even inspecting any of the new comers welds or technique) to "slow down and turn the amps up" and i would add "keep a close arc" , even to the point of touching the electrode on the workpiece in many situations.

    above all practice, watch some instructional videos and read our metalwork forum : )

    have fun with it and if possible have an experienced welder in your community to give you some pointers in real time and have a few laughs, amongst the cursing!

    laying a good weld bead can be very satisfying but takes what's called "seat time" or "hood time".

    i think i'll pull out my little inverter welder tomorrow and run a few : )

  5. #20
    Join Date
    Nov 2004
    Location
    Port Pirie SA
    Age
    46
    Posts
    808

    Default

    When chipping slag attack the edges with a sliding motion
    Keep a small block of steel or a cold chisel handy(something with a little heft to it that is handheld) chip away the glass/flux by tapping the rod end on it to restart a used rod like its a freshy.

    "So you don't get the cold lumpy start ,strike on a waste metal strike plate - run for a few moments- and quickly break the arc and jump across to your start location while end of the stick is still red hot. Do It quick! do not dawdle." GC
    I'll add, put it right next in line to your weld and lead straight onto it without breaking the arc
    ....................................................................

  6. #21
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    3,779

    Default

    I have a couple of old AC arc welders and a cheap crap Mig welder. When welding thin tube, I end up using the arc welder because I get frustrated with the Mig. One thing I have learnt when welding thin tube with a arc welder, if you blow a hole in the tube and you want to fill it, use a thin sheet of copper plate to partially cover the hole and fill bit by bit.

    Also, if you are using stainless electrodes, wait until the weld has cooled before looking closely at it. As the weld cools down and the metal contracts, the slag has a tendency to spit in your eyes!

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  7. #22
    Join Date
    Jan 2004
    Location
    Mackay North Qld
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    4,421

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    One bead stops, the next one begins - can you see the join?

    Ok! This is a how-to for an invisible stop-start for when you electrode runs out and you have to change and start a fresh one.

    The first electrode bead ends with a crater-like depression.It is a place where cracks can start and generally if left unfilled doesn't look that great. On finer work, it is regarded as a defect.

    To look more like a gun welder strike your new electrode a bead width ahead of the crater-that's downstream - and lift then back up into the crater quickly to match the last of the ripples of the first bead with the new ripples made by your second electrode arc.

    Yes!! Of course, it does take some practice but after a while, where that restart area was, becomes very hard to pick (and with a polish from the wire brush) it often looks like one continous run.


    Grahame

  8. #23
    Join Date
    Mar 2008
    Location
    Brisbane
    Posts
    30

    Default

    Welding thick steel with a home welder can result in poor penetration, preheating the job before welding helps

  9. #24
    Join Date
    Jan 2004
    Location
    Mackay North Qld
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    4,421

    Default

    Quote Originally Posted by Gringo View Post
    Welding thick steel with a home welder can result in poor penetration, preheating the job before welding helps
    I feel the above is misinformation picked up on some American Welding Forums where they seem to have an obsession with the penetration characteristics of arc welding to the detriment of many of the other important factors. It is bad information to start with and then repeated by - the monkey see -monkey do's who post it on all other the other boards and when it is not corrected it then becomes "fact".

    Firstly a generalisation is being made about home welders. Some "home welders" these days, are far better than commercial welders of old.

    I feel that you are trying to say that low powered or underpowered welding machines should not used on an overly thick plate. That I will go along with to a certain extent.

    The electrode diameter and the current it should be run at, is usually geared to the plate thickness and it follows, the amperage capability of the welding machine to hand.

    Preheating heavy plate is not related to penetration of the electrode. However as the plate is cold and a freshly started electrode won't fuse for the first few millimetres as the arc energy (read heat input ) is being absorbed by a huge metal heat sink- the heavy plate.The arc energy does catches up after a few millimetres of travel and the metal adjacent to the arc comes up to welding temperature.That is, of course, if the electrode is of a size capable of taking the amps setting required for this to happen


    (From the TWI welding site)

    quote-
    Preheating is the process applied to raise the temperature of the parent steel before welding. It is used for the following main reasons:


    The slower cooling rate encourages hydrogen diffusion from the weld area by extending the time period over which it is at elevated temperature (particularly the time at temperatures above approximately 100C) at which temperatures hydrogen diffusion rates are significantly higher than at ambient temperature. The reduction in hydrogen reduces the risk of cracking.


    To slow the cooling rate of the weld and the base material, potentially resulting in softer weld metal and heat affected zone microstructures with a greater resistance to fabrication hydrogen cracking.-end quote)

    If penetration is so greatly desired a far better way of gaining measurable penetration is to reduce any steep drag angles and keep a shorter arc lengths.Having performed hundreds of fillet bead penetration break tests, I can personally assure you that the above two measures are by far and away the most effective means of securing penetration.

    Regards
    Grahame

  10. #25
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    4,421

    Default

    The hot start
    With reference to above post #22, #23. #24 this post is very pertinent.

    Starting a stick weld bead from cold on the edge of a section or plate, strike the arc downstream 6-10mm and then flick back to the edge and start the weld bead. The electrode and surrounding metal will be brought up to welding temperature with better sucess of fusion from the beginning of the bead.

    The other parameters such as arc length, correct electrode drag angle and amperage settings will need to be correct.

    Grahame

  11. #26
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
    Age
    67
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    2,607

    Default

    Just to confirm or dispel my belief, Grahame: I have welded structures as thick as 1-1/2" (38mm) thick with my 130A AC welder without any apparent issues. I understood that the edge preparation was the critical prep. Because I could only hope for something like 1/8" (3mm) penetration with a 3.2mm rod, I left about 1/4" (6mm) unbevelled and a small gap in the setup - maybe 1/16" (1.6mm). Did the root passes from both sides (where possible) first and then filled the large V layer by layer with butting beads alternating fronm the sides. Where I could get access to the other side, I did the same thing there after about half-way and then returned to the first side to finish off - then finish the other side. Took a while in each case, but appeared good and has lasted ever since.
    One of those jobs involved fabricating the entire tailstock of my first lathe. Thinnest piece of steel was 3/4" (19mm) thick, the barrel part was 2" square bar. Obviously the whole thing was quite distorted at the end and I annealed/normalised it over 12 hours in our fireplace before machining. It's still in daily or so use.
    Should I have not attempted that or should I preheated to a few hundred degrees? I'm quite likely to attempt something like that again on my hydraulic press in progress with 1" x 3" flat bars but-welded. With a lot more at stake than a tailstock, I'd like to know.....
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  12. #27
    Join Date
    Jan 2004
    Location
    Mackay North Qld
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    Default

    Hi Joe ,

    There was not a thing wrong with the way you tackled your tailstock.

    Should I have to do the same the only thing I would change is to get a larger capacity welder-ie bigger amperage. I can fully understand in your case another welder may not be been justified.

    The reason is that multi passes of smaller diameter electrodes have more heat input into the weldment and consequently more distortion. The post heat was useful in helping to equalise any stresses built in by the welding and subsequent distortion. Unless your tailstock plate was a high carbon alloy any preheat would have had little or no effect.

    The use of larger electrodes giving a smaller over all heat input seems counter-intuitive, I know, but that's how it is. The only time I had to work out the kilojoule input into a job out was in my exams for Welding Supervisor Certificate and have not used it since.

    When you are dealing with the higher carbon steels it can be critical. Pressure vessels and steel subject to high loads, crane booms and gantries etc.. are quite different to the low carbon steel that most of us weld all the time.

    I jumped into the post above as I see this sort of thing all the time in the overseas boards. Statements like preheating manganese alloy steels ( you keep that alloy to minimum heat input ) and the real gem was about placing cellulose electrodes in a hotbox.Anyone that uses them should know that there is 2% moisture content in the flux-the moisture is what makes them bite in.

    Is there any chance of a picture of your tailstock as it may inspire the chap who bought the red Colchester Bantam lathe without a tailstock?.

    Cheers
    Grahame

  13. #28
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
    Age
    67
    Posts
    2,607

    Default

    Thanks for the instructions and explanations, Grahame.
    Here are a couple of old pics of the tailstock.
    The second one shows the size of the fillet at the bottom of the vertical 1" thick plate, because I wanted that 'look' and did most of the preparation on the rear.
    Oh, and I may have a tailstock for the Bantam - we've been communicating by PM....

    Tailstock.jpg

    Tailstock1.JPG
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  14. #29
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    66
    Posts
    3,380

    Default

    Thanks for the pics Joe, looks just like a bought one, make that a cast one.
    Thanks to everyone for the comments and tips, most I'd forgotten.
    Kryn
    To grow old is mandatory, growing up is optional.

  15. #30
    Join Date
    Mar 2008
    Location
    Brisbane
    Posts
    30

    Default

    Grahame, my post isn't based on something I've read, it comes from experience, I'm an old boilermaker,
    I started my a apprenticeship in 1972

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