Frame strengthing gussets

[Lane]

[quote="CalScot"]
I might have to post pictures of my frame failures and the repairs because they are not anyhwere near the failure areas Randy has had.
[/quote]

Please do!

[Radowick]

[quote="DarthChicken"]
[quote="Spanky"]

  These images are of my using measurements than from my car as close as I could measure it. I really think I got it very close. So why your "lower longtitudinal frame members do not extend (more than 1/4 inch or so) beyond the crossmember shown in blue" is something I can't explain. But these images are what my car does look like for sure.     
[/quote]

here is what mine looks like, it's basically a strait down shot on that joint.

[img width=450 height=600]http://i255.photobucket.com/albums/hh12 ... 47a255.jpg[/img]
[/quote]

That looks just like my car's frame and the images posted here. One of your tubes even matches the color in my images (really, really tiny amount of humor here). 

[Radowick]

I found this:


This shows just enough heat being added to melt the wire - called brazing. I don't see any first pass weld material there as some have said was done by Brammo. I am glad that according to Randy that Brammo got away from this techique and went to a true weld with MIG. 

[DarthChicken]

So are you saying that demo joint is how brammo did it? Because if you are, you're wrong.  I took a tour of the factory, and visited my car multiple times during production, and yeah.... They did braze with copper, but over top of a weld.

The floor in the backround honestly doesnt look like brammo, and that bid was added to YouTube less than three weeks ago... I really doubt this is brammo

[Terry Kennedy]

[quote="DarthChicken"]The floor in the backround honestly doesnt look like brammo, and that bid was added to YouTube less than three weeks ago... I really doubt this is brammo
[/quote]

It definitely isn't Brammo. At the point where the full welds were done at Brammo (as opposed to the tack welds on the jig) the frame would be on a rotisserie. Also, the background music isn't nearly loud enough. Perhaps member "thewelder" can comment on whether this weld was done at Arch (UK frame fabricator).

[Radowick]

Yes, this video was just posted last month and I have no idea where it was shot.  
Darth, I remember you said you saw first-hand that Brammo made a weld pass first and then covered it with the brazing pass. And that is why I pointed out "I don't see any first pass weld material there as some have said was done by Brammo". If this video was from a early Brammo car, we should see the weld there and some discoloration of the tubes from the first weld pass. Brazing doesn't create a weld puddle where the two pieces and the filler rod all become one like a weld does. Brazing just barely penetrates the surface of both parts. Not close to being as strong as a true weld.

[CalScot]

[quote="Spanky"]
Yes, this video was just posted last month and I have no idea where it was shot.  
Darth, I remember you said you saw first-hand that Brammo made a weld pass first and then covered it with the brazing pass. And that is why I pointed out "I don't see any first pass weld material there as some have said was done by Brammo". If this video was from a early Brammo car, we should see the weld there and some discoloration of the tubes from the first weld pass. Brazing doesn't create a weld puddle where the two pieces and the filler rod all become one like a weld does. Brazing just barely penetrates the surface of both parts. Not close to being as strong as a true weld.
[/quote]

I am pretty sure this is from the UK.
AFAIK, on all UK Atom frames, the main frame is bronze brazed, as shown in the YT vid. The engine box frame section is MIG welded and some joints are MIG welded with a "cosmetic" bronze braze cover pass.

As for a bronze brazed joint not being as strong as a "true weld", well it's just not that simple.
Technically, that statement is true. A given joint to be joined will have more strength if welded by any standard method (MIG, TIG, SMAW) as opposed to a bronze brazed joint. However, both methods have good and bad attributes for a given application.

The bronze brazed frame on the Atom has been tried and tested. It has had a number of serious crashes in addition to countless thousands of hours of use amongst all Atoms. I've never heard of any issues with a bronze brazed joint failing and I have pictures of Atoms wrapped around light poles, bus shelters and all the others documented on here over the years. Simply put, the design and application of a brazed joint is successful and is strong enough for the Atom application. On the other side, the engine box section that is MIG welded has had several failed welds. Mine included and I know of more. There are likely more than one reason for each of these, but in my case, I put out too much power for the design and it simply needs beefed up. In other cases, it's probably because of crashes, bumps, off's or whatever that have loaded a weld beyond it's limit.

The brazed main frames on the Atom have many benefits. Minimal heat input is the big advantage. A fully MIG or SMAW (Stick) welded frame requires a seriously strong jig to hold all the pieces in shape during welding. Otherwise, the warping and distortion from the heat and cooling would make close tolerance frame fabrication almost impossible. This rigid jig method, means the residual stresses created by the welding are retained within the frame. This can be relieved by heat treatment but that cost's money. A bronze brazed joint has almost none of the same stresses of an equivalent welded joint due to significantly less heat input but also the speed it is heated up and allowed to cool as well. This means the frame can flex and probably absorb more bumps and stresses. So it's quite possible that your MIG welded Brammo frame has enough residual stress at the joints where it might fail as easily or even easier that a bronze brazed frame under a given load or over time.

The fact that there is still the skill and passion to make the frames the old fashioned way is not only comforting from a nostalgic sense, but it make sense too. Those Brits still have a few things they can teach us over here!

I'm sure that makes most folk go to sleep but there you go!

[FourFather]

Excellent post, CalScot! Thank you for your contribution