Oh if it were only this easy

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

I figure we will have, oh, about 120 or so hours in the cage. Maybe more.

Any advice for a first-time cage builder? Things I have learned (or already knew from other welding projects):

- Molten seam sealer smells nasty at first but you grow to like it
- Contamination sucks. The cleaner, the easier it is to weld.
- Gaps suck. Yes, it it always worth it to grind that last little bit off before welding
- Sheet metal sucks. How the f*ck do you cleanly weld to sheet metal?!?!?! My joints look crappy but they are strong
- Tubing benders are fun

Bernie Baake · **Posted:** Sun Apr 24, 2011 5:51 am

How the f*ck do you cleanly weld to sheet metal?!?!?!

start on the thicker metal plate that you are welding to the sheet metal. Spot weld in three or four different locations, then return to the first weld when it has had time to cool add another spot weld to the first and then mov e to the next, spend less that two second on each spot weld always starting on the heavier metal lapping onto the sheet metal and about half of the earlier spot weld. One second bursts are the rule But it's almost impossible not to get over ambitious and burn through.

Vincent Keene · **Posted:** Sun Apr 24, 2011 7:07 am

I'd go with the NASCAR bars in the drivers door area vs. the X-bars. They will definitely give you more protection in a side impact situation.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Vincent Keene wrote:

I'd go with the NASCAR bars in the drivers door area vs. the X-bars. They will definitely give you more protection in a side impact situation.

That was the original plan, but after looking at about a million cage pictures from some really good fabricators, it sounds like to current "trend" is bent x-bars. There have been some points made about this style being better than nascar bars since the load path is angled, and there are no unsupported bends.

Here's what we're going to try to end up with:

Donnie Barnes · **Posted:** Sun Apr 24, 2011 7:43 pm

How do you make your gussets like that?

--Donnie

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Donnie Barnes wrote:

How do you make your gussets like that?

--Donnie

Trick question? They're just taco plates. Rough cut a piece of sheet steel then push it into a taco shape in a press with a jig. At least that's the theory, haven't done one yet. I borrowed Chris Shimmel's jig, it's pretty simple.

We'll probably add a big taco plate at the driver's side A-pillar top bend also for roof "pancake" strength. And if possible add a gusset along the entire A-pillar to the cage.

I remember the first time I went to Chris's shop years ago, and was amazed at how few pieces of equipment are needed to make a cage. It's 90% craftsmanship.

Back to double-fishmouthing my diagonal to make it fit the node at the main hoop top bend...

Donnie Barnes · **Posted:** Sun Apr 24, 2011 10:20 pm

MikeWhitney wrote:

Donnie Barnes wrote:

How do you make your gussets like that?

Trick question? They're just taco plates. Rough cut a piece of sheet steel then push it into a taco shape in a press with a jig. At least that's the theory, haven't done one yet. I borrowed Chris Shimmel's jig, it's pretty simple.

Not a trick question. I assumed there had to be a "jig" for it, just haven't seen anything. I mean I've seen press brakes and such, and even brakes for use in normal hydraulic presses, just nothing that specifically did that. But obviously it exists.

Just didn't occur to me it was something you could just pick up somewhere easily, I guess.

Looks damned nice done that way, and I like the strength component of that versus NASCAR bars, especially some I've seen.

--Donnie

Carl Fisher · **Posted:** Sun Apr 24, 2011 11:35 pm

Not like I'm any expert on it, but I've heard so many people telling horror stories about how their cages failed tech because they didn't weld all the way around their roof joints. Some people cut the roofs off and reattach them to get the access they need, others cut holes in the floor to drop the legs through. But that's for rally- I don't know if road racers care so much about that. If it's for Lemons, why not just use PVC?

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Carl Fisher wrote:

Not like I'm any expert on it, but I've heard so many people telling horror stories about how their cages failed tech because they didn't weld all the way around their roof joints. Some people cut the roofs off and reattach them to get the access they need, others cut holes in the floor to drop the legs through. But that's for rally- I don't know if road racers care so much about that. If it's for Lemons, why not just use PVC?

I don't like the hole-in-the-floor option, and there is too much structure in the pillars to chop the roof off. We debated all the options. I am pretty sure we are going to be able push the cage forward and off of the pads (which are 2-3" tall) for the access we need for the roof welds, then up and back onto the pads. IF that doesn't work we're going to sawzall access panels in the roof to weld, then rivet aluminum plate back on top.

As you said, hey it's a Lemons car, who cares what it looks like!

BUT I will mention, even if the roof junctions had 1/2" of unwelded seam, if they are properly braced the welds wouldn't take that much load in a hard inpact. It's ALL about taking shear stresses off of the joints, and putting them into load paths through nodes. With enough bracing and triangulation a tacked cage would be stronger than a simple one with full welds.

Ryan Holton · **Posted:** Mon Apr 25, 2011 7:43 am

MikeWhitney wrote:

I am pretty sure we are going to be able push the cage forward and off of the pads (which are 2-3" tall) for the access we need for the roof welds, then up and back onto the pads.

That what we did for our car.

Carl Fisher · **Posted:** Mon Apr 25, 2011 8:00 am

MikeWhitney wrote:

BUT I will mention, even if the roof junctions had 1/2" of unwelded seam, if they are properly braced the welds wouldn't take that much load in a hard inpact. It's ALL about taking shear stresses off of the joints, and putting them into load paths through nodes. With enough bracing and triangulation a tacked cage would be stronger than a simple one with full welds.

I'm not the one you have to convince... :roll:

Vincent Keene · **Posted:** Mon Apr 25, 2011 8:25 am

MikeWhitney wrote:

I am pretty sure we are going to be able push the cage forward and off of the pads (which are 2-3" tall) for the access we need for the roof welds, then up and back onto the pads.

As I told you at VIR, that is the very reason we used the plinths. Here is a picture during our construction with the nose of the cage dropped off the plinths to be able to do a 360 degree weld at top.

clinehall · **Posted:** Mon Apr 25, 2011 9:28 am

Vincent Keene wrote:

"Oh. looking at my welds gets me hot"

Michael Westerfield · **Posted:** Mon Apr 25, 2011 10:51 am

clinehall wrote:

Vincent Keene wrote:

"Oh. look at my welds gets me hot"

"Are my balls on fire? I should look down and check!"

Michael Westerfield · **Posted:** Mon Apr 25, 2011 10:51 am

Michael Westerfield wrote:

clinehall wrote:

Vincent Keene wrote:

"Oh. look at my welds gets me hot"

"Are my balls on fire? I should look down and check!"

"You should see the sweet thong I'm wearing right now!"

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