Greg Smith

"Trigger" welds should be avoided at all costs, people do it because it's easy for a novice welder to make a decent looking(looking!) weld using that method. People equate the "stack of dimes" look to be a good weld, regardless of process. The below weld does have the tell-tale pinhole in the center of each crater, but I have seen continuous "cursive e" welds that leave the same pinhole if there's insufficient overlap, so I wouldn't say with 100% confidence that it was "triggered", but it is/was a cold weld.



I was very surprised to see this "trigger" welding on an early 996 cup that I looked at a few months back(let me know if the pic doesn't show up). The same technique was also used on tube to tube welds.



Over what time period?

Matt Romanowski

IMHO - that cage is a total failure. The person driving is lucky to be alive. The main hoop failed. The harness bar failed. The A pillar bars failed. Welds failed. The guy should have bought a lottery ticket.

People on this forum are all about safety and buying suits, helmets, FHR, harnesses, containment seats, etc. Without a good cage all of that is useless. Check out these photos from a NASCAR crash. The cage was find and the safety cell not comprimised - all at over 200 mph.

KnowSomeStuff

+1

Anyone watching the BGB CaymanS build for Daytona?

That EXACT car had this guy's cage in it.. they cut it out.. and the one they went with was marginally better.

fatbillybob

Start stop triggering forming a cold weld I 100% agree.

This is what Miller advocates : http://www.millerwelds.com/resources...G-welding-GMAW

It is a stack of dimes weld or MIG like TIG. IMO the reason for doing MIG like TIG is because one of the vital skills learned with good TIG welding is to know what to look for when you look into your weld puddle. When you transfer those skills to your MIG welding you fully understand the process. The problem is too many self-taught welders start with MIG and just shoot spagetti.

kcpaz

+2

Mark Dreyer

I thought I'd post a plug for Titan, the shop that did the cage in my Boxster S. They also did the cage work for Rum Bum and BGB's race cars.

Take a look at these pics. Pretty awesome cage eh? I hope I never get a chance to verify how good it is. You could do much worse than having this shop handle cage work for your race car, in my humble opinion.

And no I have no financial interests in that company, I'm just a very satisfied customer.

kcpaz

WOW, there's a lot of good ideas in that cage that are poorly executed.

sbelles

Yes, but that "stock" car is a roll cage.

Matt Romanowski

Sorta. Take a look at how they are built and from the sills up is applicable to one of our cars.

But the point was that lets not convince ourselves that a cage that rolled a few times at 100 mph, had a failed main hoop, A pillar, harness bar, and various welds was good. Cages are built everyday that survive bigger impacts - that is what we should shoot for (IMHO).

333pg333

You can't leave it at that...

mglobe

Such as... If you're going to criticize, give us some substance so that we can learn from it.

J richard

triangulation and load path

multi21

I don't know a thing about cages, but there appears to be many varied thoughts when it comes to the theories about making one when actually talking to the people who put them together. On the surface there appears to be no consensus. This this a black art of some sort?

kcpaz

Well first of all, I don't know how long ago that car was built, but over three years ago, I started building my Boxster cages like this...






The design is surprisingly similar, but the details are different.

If you are going to go through the trouble of building x-braces in the rear section and roof section of the cage, you may as well build it with correct load paths. I understand it makes the notching process slightly more difficult, but it's not a big deal and the finished product is a lot stronger. I have circled the tubes in question here...



There are slight misalignments in the passenger side door bars too, which isn't a huge deal really, but it you are going to go through the trouble of building a relatively high X-style door bar, you may as well align the tubes with the harness and "knee" bars. Also, the braces on the upper driver's side door bars seem pretty pointless without continuing down to something else on the lower bar. And if you're going to go through the trouble of doing that, why not create some triangulation at the same time to add rigidity to the chassis?



I'm not saying the cage is unsafe or not legal, I'm just saying that it seems like someone went to a lot of trouble to build an "excessive" cage with extra bracing in ways that aren't exactly correct.

friscocayman

kcpaz - that's one awesome cage!

Saved my butt twice and still going strong.