Here's how I joined a tube to a plate, with a sort of muti layer approach, piling on new metal until it looked strong enough. I was careful to remove every trace of slag from each weld before moving forward. I guess it's a form of root and cap. Is this approach a reasonable one, leaving appearance aside? I took it further on the other side of the plate, as can be seen in another image on the 'arc welding a bicycle frame' thread.
- Thread starter GeorgeB
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Dogbreath23
The legend of the black bogey...
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is this your bike frame that you are weldiding George? take care when you ride it mate, you've got some nasty looking blow holes and cold laps( molten metal laid over the top but with little penetration)This means the weld will have some weak points deep into it and may fail under stress! Maybe grind the whole lot back to see whats going on underneath before doing anythig else!(the gold paint looks pretty cool mind)
I'm fairly sure there's no blow holes or cold laps. The 'holes' are from where different layers of weld have ended up. I ground back a similar weld and there's no evidence of low penetration as far as I can tell.
zzr1200
Working at 650 ft on open steel work.
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scarecrow
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first you should have welded a piece of round bar to the plate and then slip the pipe over that and then weld the pipe to it that will take the wait off the weld
ark welding is very hot for welding light pipe and can under cut and weaken the pipe very easily even for an experience welder
ark welding is very hot for welding light pipe and can under cut and weaken the pipe very easily even for an experience welder
scarecrow - thank you for your helpful comment. Yes, I'm more interested in the nature of the joint on this thread, than I am in the application (bicycle) or risk (road safety). I guess there's no easy means of determining if the pipe/tube has been weakened. I assumed that if the weld penetrates but doesn't blow right through (which is what happened) that's good enough but, from what you say, perhaps not.
I'm in the process of grinding back the main bead, which looks as if it could be a 'cold lap', to check the penetration. I'll take photos of that, tomorrow.
Dogbreath23
The legend of the black bogey...
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yeah honestly George, I'm not dissin' you or anything but from where Im sitting I can see at least six possible weak points on that weld! Hey do you know how to use dilute nitric acid to test the HAZ on a weld?
Dogbreath23
The legend of the black bogey...
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Its a form of destructive testing.
Dogbreath23
The legend of the black bogey...
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The gold paint does look cool tho'.
It would be useful if you could indicate where they are. Not easy to describe, I know! I'll try and take a clearer photo tomorrow, in natural light. It's not gold paint but a photographic quirk from the use of a light which looks yellow. I'd be interested to know more about the use of dyes, acids or whatever to test a weld, and what does HAZ stand for? Also, is the use of these dyes/acids followed by slicing up the joint, i.e. destructive testing?
the snooper
getting older by the day
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i think you would have done a lot better using your mig
i started out arc welding on cars going on 30 years ago and athough like a lot of people i could do it no trouble, given the choice it would be mig every time unless i had a tig which i dont
.
also as earlier mentioned some of the welds look a little cold (in red) they are just sat on top of other welds no penetration, unlike your weld underlined in blue which has penetrated well.
bit of an expensive bike using 24 carat gold though
i started out arc welding on cars going on 30 years ago and athough like a lot of people i could do it no trouble, given the choice it would be mig every time unless i had a tig which i dont
.also as earlier mentioned some of the welds look a little cold (in red) they are just sat on top of other welds no penetration, unlike your weld underlined in blue which has penetrated well.
bit of an expensive bike using 24 carat gold though
Many thanks for marking up the photo - that's great. After the earlier comment, I could see the (top left red marked) weld bead looking a bit proud of the surface, so I've started filing it back to see what I uncover. Perhaps 80A arc is not enough power for running a bead over a thick bed of underlying steel (4mm plate plus perhaps 3mm of earlier weld).
the snooper
getting older by the day
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in think alot of it is down to experience and technique if i were you i would practice using 3 or 4 mm steel so you have no worries about blowing through and wrecking anything i like using arc on heavier stuff but easier and better results with mig on thinner material.
practice makes perfect so they say
ive practiced alot on the lottery and still cant master it
practice makes perfect so they say
ive practiced alot on the lottery and still cant master it
Dye penetrant inspection is non destructive however the welds on the forks aren't going to test well as they are due to all the crevices that'll trap large amounts of dye (like the gussets did in the link). Search the forum for 'DPI' and/or 'dye penetrant' been a few threads on the subject, Hitch posted one a little while ago but this one shows what it's not supposed to look like! Obviously weld could be ground smooth first but that can hide cracks and the like as DPI only works on flaws that reach the surface i.e. grinding/sanding can smear material into/over the finer flaws
Acid etching/macro etching is destructive. Again been mentioned a few times on the forum and google will turn up a bunch of hits too. With the correct reagents will highlight HAZ (heat affected zone) and show a lot of other detail. Nowhere near as much detail but battery acid will highlight weld fusion. Weld needs to be sectioned and polished before applying a drop of acid and waiting (cup of tea or beer if using battery acid, much quicker with nital). Example of a fillet etched with battery acid here, clearer in real life than in the pic but you can just make out the weld
Acid etching/macro etching is destructive. Again been mentioned a few times on the forum and google will turn up a bunch of hits too. With the correct reagents will highlight HAZ (heat affected zone) and show a lot of other detail. Nowhere near as much detail but battery acid will highlight weld fusion. Weld needs to be sectioned and polished before applying a drop of acid and waiting (cup of tea or beer if using battery acid, much quicker with nital). Example of a fillet etched with battery acid here, clearer in real life than in the pic but you can just make out the weld
I've filed back one of the uppermost weld beads to see what it looks like. I can't see any evidence of poor penetration. It looks like everything is bonded perfectly well but perhaps I don't know what I'm looking for. The whole purpose of these welds is to bond the plate to the tube, to reinforce or replace the original brazing. I could use more than 80A for the plate but once I get near the much thinner tube, high power wouldn't do at all.
cookie munsta
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did you get the pipe from an aged/ existing bike? if 4140 then it is now stuffed.bike frames are made from a higher tensile steel,or here they are. tig or not to tig?
It's off a bike from the 1980s. I don't know the steel type. Why should it be 'stuffed'? If so, will it snap, or what?
Drains
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Hang on there boys. Why does anyone think that weld is going to crack? It's not, no way, no how. It might look a pretty ropey series of welds, but the important point here has to be, surely, where is the weakest point on those forks? It's far more likely to be the fork tube immediately North of the welds.
If a crack's going to happen, it'll be there. Ever welded an exhaust pipe/silencer joint - when it goes, again (they always do), it's not the weld that breaks.
If a crack's going to happen, it'll be there. Ever welded an exhaust pipe/silencer joint - when it goes, again (they always do), it's not the weld that breaks.
cookie munsta
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My body weight has not been on a muffler part before but it has on a bike. can tell you in no uncertain terms that when they go they hurt. that weld won't give way right away, it may crack slowly cause the weld is strong and the pipe is strong but the Heat Affected Zone in between is weakened.
I'll proceed with caution, and assuming I live to tell the tale, will report back each year, if it lasts that long, or sooner if it breaks. I will follow the advice of checking the forks and welds quite regularly for any signs of fracture. This must be a very vulnerable type of steel tube, if it's seriously damaged by welding and adjacent heat. I've never heard of that concern being expressed over any weld on a car, but I'm no expert on different steel types. Thank you for the various suggestions.
