Yes, I deleted the 'final' photo when I realised there was more work required. I'll post an updated 'final' image in due course. I've welded a small plate on to the rear forks, from which to hang the brakes. I'm getting over-confident with this arc welding lark, but had my first 'blow outs' for ages - not through the bike tube but 'nibbling' away at the edge of the plate I added, of about 1.2mm thickness. It looks a right mess but it's functional and, as I said, the worse the bike looks, the less likely it is to be stolen.
- Thread starter GeorgeB
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chunkolini
celebrity artiste
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Just watch that you done get sued by the bike thief with no face.
Good luck, Chunko'.
Good luck, Chunko'.
Dogbreath23
The legend of the black bogey...
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You've gone very quiet the past few days George. You havnt fallen off your bike have you?
I'm waiting for the paint to dry before posting a final photo. Having looked at various websites on different types of steel, I can understand your concerns but I'll still be gob-smacked if any of these tubes break as a consequence of my welding. My best hope is that it's a basic, cheap bicycle frame and they used basic, cheap steel, possibly better suited to welding than the more esoteric types.
clem dog
Its just not fair!
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George, I would not like that one bit at all. I have marked the weld that looks, quite frankly, scary. It looks cold with no penetration to the tube, at all, plus I have drawn a line where there seems to be no fusion to the plate. The weld below it also does seem to be cold too.
You seem to be trying to keep the heat down so as not to change the metalurgy of the tube which seems sensible. But at the expense of safety? In an application such as this, I would be afraid to use it.
Maybe we have all gone mad here talking about how this and that could go wrong and you could cause yourself an injury, but then most of us have taken a tumble from a bike at some stage or another in our lives. All the replies in this thread are just opinions for you to take into consideration. If you are happy with it then its your call......
Clem
You seem to be trying to keep the heat down so as not to change the metalurgy of the tube which seems sensible. But at the expense of safety? In an application such as this, I would be afraid to use it.
Maybe we have all gone mad here talking about how this and that could go wrong and you could cause yourself an injury, but then most of us have taken a tumble from a bike at some stage or another in our lives. All the replies in this thread are just opinions for you to take into consideration. If you are happy with it then its your call......
Clem
Dogbreath23
The legend of the black bogey...
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phew! thank goodness you're still with us George! By tghe way did you look into doing a spark test to determine what type of steel you are dealing with?
Drains
Yeah, nah.
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Yep!
It sounds too small a difference in spark colour to be able to obtain a conclusive result. In addition, my spare tubing is off a different bike and could be a different type of tube, so no meaningful test is possible.
Drains - I'm logging sceptical comments like yours. If the bike holds up for several years, I'll remind you of what you said. Of course, the reverse is also true.
Thank you for your observations and for marking up the photo. The only purpose of the plate is to hold the rear brakes. Now, that might sound quite important but, there's always the front brakes! This isn't a car. The joints seem very strong. If the joint is a bit cold, it's to my advantage, as you say, in keeping the heat effect down on the tube.
How strong is a slightly cold weld with minimal penetration? Isn't it still stronger than a brazed joint?
BChild
SIP - enough with the mods!!!!
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You owe me a coffee (I'll clean my own keyboard and moniitor ) as I can't drink it when it's on the screen and keyboard
You owe me a coffee (I'll clean my own keyboard and moniitor ) as I can't drink it when it's on the screen and keyboard
It's more about having a good laugh then! I'm sure that if this work had been done with a Lorch, some of you would be far more reluctant to express doubts, even if the joint quality was no different (in my unskilled hands).
BChild
SIP - enough with the mods!!!!
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Hey I've not said a word about the welds
but seeing as you you prompted I personally I reckon you'll be fine - I had a face tarmac "conversation" when a set of un modified braised forks failed - sure I understand the concerns raise by others but hey ho experience is what you get when you don't want it so I'd say go have fun and live a little
clem dog
Its just not fair!
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In case you had not noticed George nobody has made any comment on your equipment here, just that you are trying tm weld something that may compromise the integrity of the metal and that is probably too thin for arc welding. Most on here have recommended brazing for this purpose and not welding for that reason. Like i said, if you are happy.....
Clem
Clem
You're right about the equipment aspect and I should be grateful! This frame tubing is not too thin, though. It can't be, given the ease with which I can weld it without blowing holes. Other than the possible/probable threat of heat damage, it seems ideally suited to arc welding. There's no part of that bike that I wouldn't arc weld, if I needed to.
cookie munsta
Member
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forgive me if I am mistaken, but have you posted pictures of similar projects in other threads, does a push bike require that much re-building or is this an enterprise consisting of more than one bicycle?. you have been advised that this is not a wise, safe/ recommended way in which to weld bicycle parts, and as a project the rebuild looks ok and if you comfortable with the weld quality then thats ok too and people welding and making projects and having fun creating things is what it is all about. As an enterprise it is not advisable.
other wise have fun on your bicycle
other wise have fun on your bicycle
chunkolini
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Go with it George but do keep an eye on that fork.
Oh and keep us updated if there any developments.
Your next mission is to build a tallbike.
Chunko'.
Oh and keep us updated if there any developments.
Your next mission is to build a tallbike.
Chunko'.
I certainly will! I must say I wasn't aware that there are many incidents of bicycle accidents through frame failure, but the ones that people here have reported do seem to relate to failure of a brazed joint, or other factors, and are nothing to do with any welding HAZ. I'm sure weldequip is well meaning but his scare story is a bit like when salesmen knock at the door and try to persuade you to have a new roof or something, saying the old one is about to collapse.
I'm only building/modifying one frame. The other thread related to the specific aspect of multi layer welding.
A lot of the failures are due to fatigue. One of our materials lecturers' pet hobby-horse is fatigue failure in bikes. He's been involved in several court cases (as an expert witness) where it's been necessary to prove whether the failure of the bike caused the person to be injured or whether it was the person falling off that caused the bike to fall and break. Things that apparent go commonly are cheap cranks and, believe it or not, handlebars. There was, again apparently, a case where minute rings machined into the handlebars for nothing more than visual or tactile effect were acting as stress risers and led to eventual failure. My point is, George, that although the join may look strong over many load cycles it may still fail. A lumpy weld with abrupt changes in geometry will concentrate stresses to a far greater extent than a smooth one, so it's not just about the aesthetics. The fact that the bike is made from steel as opposed aluminium works in your favour as steel has a 'fatigue limit'; a stress below which failure will not occur regardless of the number of cycles. It's entirely possible the stresses will be below this level. On the other hand... I'd just keep an eye on it.
