Slightly annoying thing: 2 (spine frame weld fail)

Just a few little things that no one seems to have thought about here.
Regardless of how great the welding looks or not, that is no guarantee of strength!  OK, if it looks shit it is shit and if it looks good in "MAY BE" applies but the "may be" is very important!
As someone mentioned inox filler rods, yes this is great if you are not interested in the ultimate strength and integrity of the finished weld, but looks are more important. But, it will generally not be as strong as it should be and you should NEVER use inox fillers with most high carbon steels as carbon precipitation will weaken the weld enormously!  Even though it may look good!  (PS in my opinion the sexy rollcage X weld pictured is done correctly (other than the pinhole due to too fast power release) and with the correct filler wire as far as one can tell from a pic)
I used to be welding certified in ferrous and non ferrous metals for airplanes. (stopped biyearly re-certifying due to lack of time) and in numerous tests the welds were tested to distruction and always Xrayed etc,  the welds were also tested for carbon embrittlement and other brittleness tests.

In my opinion the shock bracket broke, just as Lothars side stand bar, due to embrittlement of the material and / or weld , not penetration as you can see no elongation of material to suggest even a slight deformity before fracture.
If the frame is made in something like T45 or Reynolds 531 or latest spec 953 then it will surely need to be fully heat treated after welding to at least normalize it.  This is why people like Harris use Brazing techniques that use far less heat and end up being superior to welds for many reasons and in many instances.  

I do agree though that if you are selling items to the public that could endanger their lives if not done perfectly, you have a responsibility to make your quality controll of the highest standard!  This should have never happened!  Not even on a home build!

Julian
 
Ah, bugger. I'll fix it, I have to cut the welds to break them off!
Not always pretty, because I can't see what I'm doing, but strong as an Ox(an)
 
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I see I commented on this thread a couple of times so I'll add a bit more.
As Julian says, Harris use a brazing technique which at this point for steel tube frames is probably the best way to do joints.
It's bronze welding done with a TIG torch.
My local craftsman TIG welder who I've mentioned previously, had to make two sets of F5000 Lola wishbones recently. The owner wanted them done as original - bronze welded. So he read up on the TIG technique - and spent a day practising - and swearing.
They finished up as good as those Harris pics. Everybody happy.
 
Thank you chrisk.

At first I thought you were poking fun at my annoying questions in the other topic but I think I've now figured out that you're building a bike based on the Bruehl frame and a Breganze twin motor "SFQ", have some frustrations with that and helpfully pointing me to that history? Excuse my absence from this forum for many years so I reappear now as a "newbie".

I am of course very interested in experiences with building bikes around that frame. I'm debating with myself (and that depends on how many beers or glasses of wine consumed as to who wins!) whether to try to improve the old and unique Trackmaster frame I have or replace it with something more suitable for the loads coming from modern tires on the paved racetrack.
 
chrisk said:
Yes it is, now cut into lots of bits and resting in a jig. Waiting for my welder man to get into it.

TThe whole debacle happened in 2012, how time flies.
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Yeah mate time does fly. Can remember when you first go it and the bad welds that came with it. If I had the time id love to make my own for the spare motor I have.
 
motoddrob said:
Hey CK, that spine frame you brought, was it a Bruehl??.
As far as I'm aware all spine frames are a copy of Eglis
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No, Rau also made spine frames and the Brühl frame is more a copy of the Rau design: Egli put the headstock tube in front of the spine tube while Rau cut the spine open and put the tube through the spine, which is the major and obvious difference. There are some more, but I'll leave it to that.
 
I have taken many welding tests and retests, never forget that the apearance is only 5% of the marks achievable, its 90% in the post welding testing, and the other 5% ??
CLEM
 
I must agree that the quality of the welds do not look good, however in the case of the shock mount this tube mainly acts as a spacer and the bolt, which I assume is a through bolt and as such would transfer the load to the gusset on the frame.
Just thinking.
 
Exactly what Burkhardt told me when I made him aware of what happened... That said, he meanwhile changed this spacer from cylindrical shape to a T-shape, sticks it through the hole in the bracket from between the 2 rear subframe tubes and welds it to the bracket from between the subframe tubes and from outside . This way, it is even more solid than it was before... ;-) He clearly stated that it is not necessary to do it this way, but he wanted to avoid any discussions for the future on this part.
 
Now I know what I can do with all my bike magazines and I should ask my wife Eva to move the bikes in the sitting room.
Can‘t bring the magazines in the garage, it‘ s to wet.😰
 
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to be honest, I have to move all parts to my shed this weekend as I want to mount a complete engine for exact measurements.:)
 
Is that a Bruehl frame? The steering head tube and top engine mounts do not look what we have seen of his frames previously here?
These are a couple of pictures Burkhardt sent to me recently when I asked for information but I am still waiting for some words to accompany the photos.
Or perhaps each of his frames is unique and built as requested?
 

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some words to what Burkhardt does to maybe balance a bit of what was written before: The hole in the spine tube gets machined by a CNC Machine to make sure the angle is accurate. He then fills in the steering head tube, welds it in and closes the spine tube on both ends, then he returns that to the machine shop to CNC machine the bearing seats, then it gets mounted into a rig that is set up by cross-lasers to make sure everything stays in line etc. etc. etc.

Burkhardt pays huge attention to accuracy and straightness. where ever possible, he uses a spirit level to get it as accurate as possible. Any failure (just like the one with the shock distance pieces, which even wasn't a real failure as the distance-pieces should never see that kind of load as it was given here and were only welded in place not to drop off the frame really) he looks to improve his design. I think it really evolved over time and makes for a very good and stabile frame system. The one I rode around the block was one of his first frames that he is still racing.

Burkhardt is also doing Porsche 917 space frames for the french Porsche club out of light weight, very strong alloy (used for Mountain bikes or down-hill bikes normally). This frame is even put under pressure to make sure when a crack appears, you will recognize it right away. He also re-designed the frame to have two oil tubes incorporated to make it possible to have an oil-cooler mounted at the front which is connected to the engine through these tubes instead of flexible oil-lines, which is not allowed on the event they race the 917 in.
 
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