john87

ha ha!! I have often been asked to write a book, but not on welding!! Yes, as you say, preparation is EVERYTHING. When i was out and about welding many years ago, i would have people say stuff like "How slow are you, my mate could have done that in 10 minutes" I always used to say that, "yes, but it would fall off ten minutes later too.." As you know, leaving aside the type of joint [so the preparation as regards plate edge prep] there is the matter of cleanliness. All mill scale and anything else MUST be removed.. You see, apart from the fact that we do not want random shit floating about in our weld pool [and the fact that thick mill scale can make life difficult as regards fusion at the edges of the weld] mill scale is iron oxide, when you heat it up, it will liberate oxygen, not a great idea.. Same goes for rust, that will liberate oxygen, and water too.. Why do we not want water or rust?? For the same reason that we do not want oil or paint or anything else. You see, water [and much else] contains hydrogen. Hydrogen is possessed of the smallest of atoms. It/they, are in fact, the smallest atoms of all.. The hydrogen will dissolve in the weld metal, this then cools and solidifies, leaving the tiny hydrogen atoms trapped in the interstitial spaces between the atoms of our base metal. Especially, in higher strength steels, over the next few hours or days, this hydrogen will attempt to "escape" generating HUGE pressures as it does so. These pressures will literally tear the steel apart, creating what is known as "cold cracking". The joint appears to be perfect at first, and then, some hours or days later, BANG, and a crack appears, parallel to the weld and in the heat affected zone, although it can be in the weld metal itself. This obviously is not good!! Out of interest, one of the tests to demonstrate this sort of thing, involved cutting out a portion of a welded joint, and immersing it in paraffin. The bubbles of hydrogen can clearly be seen rising... Ok, how much hydrogen we talking about then?? Well, it can reach 40ml of hydrogen per 100 grams of weld metal, so 8 teaspoons of hydrogen for a piece of metal that weighs only a few ounces.. Anything above 15ml per 100g is considered high though, with the attendant risk of cracking.. What can we do about this then?? Well, there are two sources of hydrogen to consider; The first, is contamination, but we have covered that, the next is the hydrogen that emanates, or presents itself, as a consequence of the welding process we use. Gas shielded processes are better in general, so long as the gas is dry. The biggest process related factor is moisture in MMA consumables [welding rods] There are three basic types, these are, cellulosic [i will not talk about these, as unless you are doing pipe roots, you will not come across them] rutile, and basic [basic refers to the chemistry of the things..] As i said earlier 15ml of hydrogen per 100 grams of weld metal is considered high. 10ml being "medium" and less than 5ml considered low.. A rutile coated rod contains quite a lot of hydrogen, above 15ml, but not much you can do about it.. Obviously you need to protect them from moisture and you can dry them out to some extent by "baking" them. Do not go above 100c though, as you will damage the coating of the rod.. The "basic" coated rods, your "low hydrogen" ones, these, unless you get them direct from one of them "vac pack" things you can get now, are ALWAYS redried [according to the makers directions on heat and duration] For example, the makers might state, that for a dissolved hydrogen content of less than 5ml/100g redry at 250c for 1 hour. Having done this and removed them from the oven, they then all had to be used within about half an hour, or you had to redry them all over again.. This is why the makers came up with "vac packs" You would open them, use what you needed and chuck the rest in the bin.. Unless you are welding high carbon steel or very thick sections, forget all about hydrogen in the consumables though, just make sure there is no moisture, paint, oil, mill scale or rust [or anything else] contaminating the weld area.. As you can see then, the gas shielded processes have a bit of a built in advantage so far as hydrogen is concerned, so why use MMA?? [stick welding] Ok, leaving aside the convenience, there are a lot of other advantages.. Say we want to weld an alloyed steel?? We obviously want our weld metal composition to match that of the parent plate.. Problem is, it might be impossible to manufacture MIG wire of this composition, it might be insufficiently ductile to draw into wire for example. This problem can be got around by means of the "metal cored" MIG wires you can get now. They are formed from a strip that is folded up and contains metal powder alloying elements inside.. With MMA [stick welding] we can VERY easily get around this though, by adding our alloying agents to the flux coating instead. This is a HUGE advantage of MMA, the flux acts as a "vehicle" for the transport of alloying agents.. What else does the flux do then?? Well, FIVE things all in all; These are; 1, Creates a gaseous shield to protect the weld metal DURING welding to prevent atmospheric contamination. 2, The slag forms a shield to protect from atmospheric contamination AFTER welding and during cooling.. 3, The slag slows the cooling rate of the weld thus reducing "quench severity" and helping to reduce undesirable hardening and/or cracking. 4, The slag acts as a convenient "mould" for the weld metal that is found to be helpful during vertical welding etc. 5, Finally, the slag acts as a vehicle for out alloying elements as i discussed earlier.. As you can see, there is a tendency to "write off" MMA welding as "old fashioned" but it has its advantages.. I have not written so much about welding in decades!!! john

Wish i could plaster!! The best welding process to learn with [by a mile] is oxy/acetylene. This teaches you lots of things, heat input, the distribution of heat [think welding a thin sheet to a thicker one], forming and maintaining a weld pool, controlling penetration etc. MMA [stick welding] would come next, then MIG/MAG. Reason being, unless you are skilled at "manual" welding processes, a "semi automatic" process [like MIG/MAG] will just lead you to turning out crap faster!! People with tell you that MIG/MAG is the "easiest process to learn" It is not, it is the easiest process [by a mile] with which to turn out welds that LOOK good, but which are in fact total crap.. Take stick welding... Get the rod angle more or less correct, but note that this is just a starting point, you may well have to vary a LOT from the "text book" angles to control the weld pool. Then, [and this is where most people get it wrong] you, do not just strike the arc and "set off" as it were. You have to deliberately form a "weld pool" to your satisfaction, THEN start your travel. Go along smoothly, not too slowly though, as if you do, the weld metal you are depositing and the slag will "catch you up" You do not want this, as, if the slag catches you up you will end up with slag inclusions, and, if the metal catches you up, you will not be able to play the arc on the material you would seek to weld [thus melting and fusing it] but you will end up lengthening the arc [as you are now busy trying to stop the rod getting overtaken] and letting the deposited metal get under you as it were, you will them not be able to fuse the plates then.. The arc MUST stay at the leading edge of the pool you see.. Travel too fast and you will have the same problems as you would if you travelled too fast using a silicone gun.. It is EXACTLY like using silicone. With silicone you form the shape of the bead when you start, you keep the nozzle VERY close to the work, you vary the angles to place the silicone where you want it, you travel at an appropriate speed, not too slow [as the silicone will catch you up] not too fast [as your bead will be too small and not formed correctly], and, at the end, you do a little twirl to finish off the end of the bead nicely [just as you do with welding!!] You need to keep a short arc too. [this is VERY important] Once again, think if you were using silicone, what would happen if you pulled the nozzle away from the joint about 5 or 10 mm?? EXACTLY!!!! Now, i have to say, that the quality of the welding set plays a good part too. My first welder was an SIP 160 that i got from my mums mail order catalogue. I did AMAZING things with that.. Moving on many years [and much better welding sets, Miller, Lincoln, Hobart and the like] and i saw an SIP 160 [like mine] for sale on Ebay. I had to buy it!! When i tried it though, OMG, i could barely weld with it!! Keeping a short arc was just about impossible. Not nice at all!! Form a weld pool [a sort of circular movement to establish the arc correctly and make a little pool where you want it] and after that, short arc and think silicone!! Weld humped up?? More current. Weld too wide and undercut and lots of spatter? Current too high. Oh, yes, butt welds, unless it is thin plate [when you could just leave a gap] grind out a "Vee" to place the weld metal in.. Use 6013 rods. You willl see on youtube that crazy americans are obsessed with 7018's but two problems there; 1, unless you are welding 1" thick plate or higher carbon steels it is not needed. 2, none of your "diy" type sets have a high enough open circuit voltage to run them properly.. On the usual AC output sets.. 4mm use 160 to 180A [For fillets use 180] 3.2 use 120 to 140A [For fillets use 140] 2.5 use 90A If you have a DC set you could often drop these currents down a bit, ESPECIALLY for butt welds. john..

Well that is good to know. I think i will get them to provide the saw though, not messing about with mine for no good reason. Is there anything that says that the saw you take to bits has to be the same one as you use for the rest of the course?? I am sure i will figure something out.. john..

Yes i do, but i blow all the shit out of the thing first with an air line. Doubt they have one of them in the middle of a field. john..

What i mean is, apparently, for example they want you to remove the air filter and clean it. Well, others can do as they like, but; 1, I am not taking the air filter off unless they have an air line so i can blow out all the internals of the saw first, and 2, i am most certainly not brushing the dust off the thing. The saw i would use, has a funny papery sort of filter. I DID try to brush it once, but all you do is to smear the oily stuff that accumulates on it into the filter medium.. john..

Hi all, I have been offered the chance to do a chainsaw course [for free]. I would do it, but am a bit concerned... I have read a little bit about what is expected of you, and apparently they expect you to take your saw all to bits, taking out the plug, removing the air filter and taking off the recoil starter etc?? Is this correct?? Not being funny, i am not taking one of my pristine saws all to bits unnecessarily and very definitely not in the middle of some field. What if you just tell the assessor how you would do it if you wanted to?? Can you get them to supply THEIR saw for you to take to bits?? I will gladly do that.. john..

Can i tell you why?? Because nobody ever showed you what you were trying to achieve. It would be like trying to play darts with the numbers missing off the board.. I am sure that if someone spent half an hour with you and then left you to it for a few hours, that you would AMAZE yourself with your new found skills.. john..

Oddly enough, the "good" one, is actually crap too.. All this "stack of dimes" shit, is just that, shit. It is merely a fashion. It was explained to me once [by a SERIOUSLY qualified chap] that all this came about thanks to the chinese and their cheapo bike frames. You see, a robot welder cannot weld properly like a person can, as it has no judgement, it cannot see what is happening and react accordingly. Therefore, the thing gets set to lay down what are really, more or less a series of overlapping tacks.. People saw this and thought that this appearance represented "good" welding, and so they all decided to copy it. In reality, for any serious purposes, the thing would fail visual inspection for "excessive ripple" and not blending smoothly with the parent plate. The smoother the weld, and the smoother the transition to the plate, the better, in fact, one commonly used method of increasing fatigue resistance, is to grind the toes of the weld with a die grinder, blending them in.. Every single ripple acts as a stress raiser, not to mention the effect of fatigue life caused by the rough interface between the toes of the weld and the plate. Then you have the effect that the excessive ripple will have on corrosion resistance, with the ripples all setting up various types of "corrosion cells" Lots of internet "experts" will disagree with me, but ask yourself this. Ever looked at the welds on a pressure vessel??? They were lovely and smooth, yes?? There is a reason for this.. john..

You are right. I used to love welding [hated fabricating though!!] but when my eyesight went a bit i lot all my confidence. Different world now though!! I bought a Bosch cordless drill once. Cannot remember the price now as it was about 15 years ago i think. Was in the hundreds though.. As i walked out of the shop i thought "what the heck did you buy that for" but it turned out to be one of the best things i have ever bought. The use it has had... Batteries are starting to lose capacity now, but what a drill.. john..

Hi Roys, I used to try it wearing glasses, but it is awkward as everytime you take the helmet off you knock your glasses off too. I usually wear a leather flash hood too even if only doing a small bit of welding [had a close run in with skin cancer] so i do not want the rays on me. For some reason having the lens in the mask works so much better, perhaps with glasses as the welding lens is a distance away, there is some optical interaction?? I have no idea. I could not get on with doing it like that anyway. Your eyesight getting worse creeps up on you slowly. I had a speedglas helmet years ago, but i thought that the lens must have been going wrong, so i gave it away and got an Esab one. That was not much good at the best of times and only lasted about 2 years before packing in. £250 down the drain. I had a long think before getting another.. I know someone that has a £60 helmet from screwfix. I had a quick go and was very impressed to be honest. One thing though, i know the automatic lenses go dark and light again, they all do that, but the UV protection is there all the time if you understand me, even in "light" mode?? I was worried that with all the counterfeit and other chinese crap, could the rays still get through and do your eyes in over time, as, the only think the chinese make properly are viruses.. Therefore i decided to get another speedglas one, as they are the best without any doubt at all. I have had it for about a month i think, i got it from BOC. When i tried it though, as i said, it was unbelievable. Would i buy another?? YES, if were twice the price.. I was worried what if i bought it and i still could not see clearly, but that was a risk i had to take. You can buy the lenses and maybe stick them in any helmet with double sided tape i suppose. They are about £20 the lens and come in 1, 1.5, and 2 diopters is it?? I woud imagine there are lots, but i would get a speedglas one.. It is like a different world, like having the welding ability i used to have back. Makes me feel all young again! It IS a lot of money, but as my first speedglas helmet was still working fine when i gave it away [it was about 20 years old] i have no reason to think that this new one will be any different. Speedglas do cheaper ones, but the 9001 series are wider and deeper and better suited to overhead welding and stuff. I love it.. john..

Is it your tree?? No?? then move along and forget about it, none of your business. john..

Hi All, I know quite a few of you get yourselves involved with welding, so i thought that this might help.. Now, i am a properly qualified welder, so it follows that i am quite good. [or was] Not worked as a welder for years, but with getting old and your eyesight getting worse, i lost all confidence. As you know, with welding, confidence is everything, i would be so stressed everytime i went to weld anything.. So, a few weeks ago i bought a speedglas 9100V helmet complete with the optional magnifying lens [you get the lens that matches your glasses strength] Anyway, it was expensive, about £400 all in all, but i went to try it out for the first time yesterday. OMFG!!!! Within literally two seconds of striking the arc, all confidence back!! The difference is like night and day, best £400 i have ever spent... So, anyone else think their welding has gone crap, get one of these!! BEAUTIFUL quality, just brilliant in every way.. john..

Thanks all!!! Great advice as usual!! john..

Hi All, What would cause this to happen to the top of a Cherry tree?? It is only about 7 feet tall. The idiot neighbours planted it actually touching my garden wall, so hopefully the thing is doomed.. john..

How you going to remove the powder coat?? It is terrible stuff to get off. You will struggle to sand blast it off. They use chemical baths to get the stuff off or burn it off [not recommended] john..

I do not have a CLUE about TPO's, but if what the council are doing is a statutory function, then no, they cannot charge for it unless this is provided for in the legislation. An example would be that they cannot charge to empty your bin as they have a statutory duty to do this.. john..

Now i do not know much about these things, but that looks like a good deal to me... john..

I would certainly not buy anything Chinese... You would be better off buying a decent secondhand british make.. I too was looking for a chipper once. I was looking at chinese stuff, when i found a reply on this very forum to someone else in the same position. They were advised to go buy something like a secondhand Timberwolf 13/75G [which would be about the same price range] This is what i did. I got one in BEAUTIFUL condition for a very good price too. The thing has been absolutely faultless and does everything the makers claim and more.. Ok, it is a bit of a twat when things get stuck in the feed chute and for regular use [as in tree surgeons] you would want something with a hydraulic feed, and bigger capacity [mine does 3"] but if you are not doing it all the time, one would be great.. If and when i sell it, i will get every penny back to as the first to see it will snap my arm off. Would i be saying the same for a chinese machine..?? john..

Wonder if he will come back??? john..

That is because you are white..

Do not understand what you mean??? Looks pretty dangerous to me! john..

The planning people will already have tipped off the tree lot.. If no TPO, best act quickly then.. How do you know the council lot will not do a "backdated" TPO as the law and councils are two entirely separate things.. john..

Awww, It thinks you are its mum!!!! john..

How amazing is that!! I doubt it will fly away. Probably will be really tame.. Well done you.. john..

Yes, we are clever arnt we.. tell you what, you go and unstabilise the tree without firstly informing the neighbour of the risks and agree to indemnify the householder against any claims.. Hmm, thought not..