Advice please on some welds :)

[Faaluke]

So i've had a mig for a couple months now, and have welded up a few things to get the hang of it. My latest project being a tandem bike. I've welded it all up and just want to see what people think of it. Every weld was at a different angle with different gap etc, so it is rather messy. I just want to know if they look sound or not. I will probably cut some triangle sections of steel to fit in the corners to further strengthen the section i've added in.

Any advice would be good thanks. Areas that have a lot of weld are where I had slight issues with blowing a couple of holes. But I thought the penetration I was getting was worth the couple of holes I blew / welded back up. Keen to know if they look solid or not though.

This section is 1 tube inside another, with triangles cut out of the bigger tube to allow more join area.

I would have preferred to do nice single run welds, but the tubing is 1mm or so, so I used the method on this forum for thin metals and just layered the welds to fill (at times) some decent gaps between the metals. Basically I just want to know if the welds look strong or not, and if extra strengthening is required or not. I will most likely add the plate sections in anyway, but want to know from some pros for future projects.

Cheers, Luke

 

[Barney1973]

Think you may be getting a few words of warning from fellow members,the more weld you put down doesnt mean its stronger,you have seriously weakened the surrounding steel tubing by laying so much weld down.
Not sure which pic scares me the most,not trying to put you off but that bike would be a death trap.
There is a thread on welding bikes that you should read,lots of good advice that will give you an idea of the pitfalls.

 

[Faaluke]

Hmm thanks for the thoughts. I didn't do it all in one hit, I would do a some welds then move to another section of the bike allow it to cool. Especially the one with big weld build up, that was probably 5 separate welds over an afternoon, short pulse welding on most of it. I just assumed that giving it time to cool down would mean I could safely do some more welds on it Will watch this for more advice cheers

 

[bigbadbugga]

Sorry to be the second bearer of bad news but there looks to be very little strength in those welds.

You can weld 1mm wall tube with a continuous bead, you just need to cut lots of samples and practice practice practice, play with the power and wire feed until you get a good weld.

 

[Faaluke]

Sweet as Ah well, was a good lesson I guess..

 

[McFarmer]

I think you did just fine. Report back on how it held up.

 

[cookie munsta]

Mate there is a thread already going on bicycle welding in the arc welding section. it is um, thought provoking, and might answer some question on the topic regardless of stick / mig preference.
Cheers CM

 

[Faaluke]

Yeah I read that one before actually, cheers.

 

[Dr pepper]

Despite other comments seeing as you've only had the set a couple of months what you have done doesnt look all that bad, not professional but I dont think it'll all fall apart on your first ride out.
One bead is a better idea, all in one go, if you need less power then wind it down, nuking the metal with loads of amps is not the best way, a long weld with nice continuous penatration is what were looking for rather than super hot spot welds.
Weld a couple of test tubes in the same manner as you've allready done, stick them in the vice and wrive them till they break, to see how good the weld is, if the tube bends substantially without the weld breaking you have effective welds, this isnt an aerospace test method but were not buiding planes.
One thing of note here, your better welding cheap frames, expensive alloys such as 531 are tricky to weld, the carbon content makes the weld brittle.
One of my first projects was a recumbent, I had a nasty sip weld set and hardly any experience, I sold the 'bent years ago and its still going.

 

[Faaluke]

Thanks for the insight, I have left the welder setup with the settings I did the bike with so I will do some welds on some tubing I have left over and see how much it takes to break. Next time I will try and trim the settings down on the welder so that I can get a bead going. I took down one photo which I felt was not representative of my welding as I had done a few runs over a few hours and so the original weld wasn't shown. So the weld was built up but I didn't do it in one hit as I think some people thought so heat didn't look to be a problem. I did manage a couple of bead runs, but used the method from this forum used for thin sheet. All a learning curve really as local to me there aren't many courses in welding. The course I want to do is once a year so my options are limited.

Anyways, i'll take everything on board and will work on getting my settings set better on my welder. It has adjustable amps, volts and wirespeed, so getting it bang on right is hard while learning. They aren't options like 1,2,3,4 etc either, its infinitely adjustable anywhere from 30A to 180A, 14-24V and wirespeed is similar.

Cheers Luke

 

[pedrobedro]

Grind the weld smooth and get some paint on it, it looks plenty good enough to hold two pushbike frames together. Put it between two blocks and stand on it to see if it creaks or bends, that's my usual test

 

[Alfaman]

layered the welds to fill (at times) some decent gaps between the metals.

If you get the tubes nicely prepped before starting to weld, you'll find it much easier to get a good result. Gaps are bad, that's when you start blowing holes and then you end up having to use weld to fill the gaps.

Pedro is right, they look strong enough to me. Weld in some gussets to put your mind at ease, then see how it looks.

 

[Faaluke]

Yeah that was half my problem, I tried grinding the ends so they slotted up nice and tight, but with all the tubes fitting at angles they didn't end up perfect. In future I now to make them fit nice and tight so that's a good bit of advice. Yeah I will have a practice welding on some spare tube to get the settings right then will add in some gussets and make sure I do the welds in a single bead.

I supported the frame at both ends and jumped up and down on it and it didn't break, so thats a good start :P Considering most of the strength is going to be in the triangles when its standing up and not sideways if that makes sense.

Will try get the gussets done during the week and will post up results. Thanks

 

[GeorgeB]

Yeah I read that one before actually, cheers.

What did you make of the good advice against welding bicycle tubing on that other thread, which I started? Unless you know for certain that your tubing is definitely a type which can be welded, then it must be high risk.

I know it's good advice I was given but I'm going to proceed with caution, on a wing and a prayer that my bicycle is made of cheap, basic steel, and not anything fancy. On a tandem, it must be more risky because there's always a second person to consider and I guess the forces could be rather greater from the combined weight of two persons.

 

[chunkolini]

Hmm
I think starting on something like a tandem is a bit optimistic, I started on bikes that could only kill me.

Practice on yourself before you involve other people's lives.
A picture of the whole project would be good, is that welded tube in a load bearing area? I would never have a spliced tube as part of a main structure, well dodgy. Also try to avoid welding on the sterer tube, this is most highly stressed area of the whole caboodle, I would original factory welds here on a tandem.

Then again I did make a tandem,
Back to back, both pedallling forwards, there is a clip on Utube v=but I cant remember the link. Called The Longpig. It has been on the public road and has not killed anybody.


Chunko'.

 

[Faaluke]

What did you make of the good advice against welding bicycle tubing on that other thread, which I started? Unless you know for certain that your tubing is definitely a type which can be welded, then it must be high risk.

I read it after I had done mine I'm not welding anything to do with the wheel areas like in your thread. I will post up a photo tonight to give an idea of what I have done so far. Bit hard to explain it. At the end of the day if its deemed to be unsafe I won't use it, but i'll still have fun welding it all up and chalf it up to experience.

chunkolini, I browsed you-tube and saw that video actually, but had to rush out so didn't watch it, I will do now!! Though i'm not sure I would want to ride that bike as it looks a bit flimsy haha

 

[chunkolini]

A bit flimsy?
A bit flimsy?
A bit flimsy?
How dare you, It is a quality piece of engineering so there.
Ok Ok maybe the bridge tube is a piece of 30mm tubing and the bottom joint is a length of 12mm studding and a few nuts. But hell it did not fail. Also if it had it would have collapsed gently and elegantly in the middle.

Post a linkto the video, it is short but long enough to titllate.

Chunko'/.

 

[Faaluke]

No offense was intended at all I'm sure your welds are many times better than mine, just the size of the bars looks thin Also didn't realise you didn't weld those thin parts, but instead used a bolt system, so my mistake

That's a sweet photo btw. Anyone not knowing how bikes work wouldn't know which way you're heading

In regards to the video, I may have seen a different one, probably this one: http://www.youtube.com/watch?v=5unMlXg6WL4 so may have not seen your video while browsing.

Will add photo tonight of full bike to give people an idea of what i've done.

 

[Faaluke]

Hopefully these will give you an idea of my design etc.

With this photo being what I will look at doing with some gussets (probably sounds wise due to my welds). Any suggestions more than welcome I have set up the frame to span from one end to the other and have jumped up and down a lot, but nothing gives and i'm not sure how to stress it more really.

 

[McFarmer]

That looks to be a sweet weld where the pink joins the blue. I don't know if the gussets where the gray joins the blue are needed, the force looks to be mostly directly line line. No harm though I imagine.