wtibbit

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I swear, it's like no one has ever cleaned a crab around here.

-Crissa
I haven’t cleaned a crab, but I have cleaned my bowl of crab chowder, using some bread to get those last bits. Does that count?
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JBee

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You asked, JBee delivered:

Stainless EstimatesMass kg/sqmsqmmasslbCost
SS 3mm
24​
279.2​
616.4​
$977.26​
SS 2mm
16​
11.634​
186.1​
410.9​
$651.50​
Frunk (w Grill)
2​
48.0​
106.0​
$168.00​
Tailgate
1.26​
30.2​
66.8​
$105.84​
Total ends
3.26​
78.2​
172.7​
$273.84​
Front door
1.02​
24.5​
54.0​
$85.68​
Rear Door
1.103​
26.5​
58.4​
$92.65​
Front fender
0.37​
8.9​
19.6​
$31.08​
Rear Fender
1.532​
36.8​
81.2​
$128.69​
Cabin Frame
0.162​
3.9​
8.6​
$13.61​
Total 2x Sides
8.374​
201.0​
443.7​
$703.42​
Total Opening SS
7.506​
180.1​
397.7​
$630.50​
Total Fixed SS
4.128​
99.1​
218.7​
$346.75​

Where's my cookie and milk? :ROFLMAO:

Note only 218lbs (99kg) of the SS skin is actually attached to the vehicle body, the rest are opening doors, tailgate and frunk, so how much would they improve the structure? BTW this also means that EM moved most of the SS structure to the door skins, and NONE of it would help the vehicle structurally....except for crash ingress protection on those openings.

A couple of pointers:

MY casts are heavier (but stronger) than the plate assemblies they replace
F150 Stripped Frame 450lbs
But...frame geometry is king!

And seriously, if there is no load on the fenders or skin then how can anyone claim its structural?

Silly talk.
 
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Bill837

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I agree, but being no longer depending on an exoskeleton for structural strength, they could easily have reduced the thickness from 11 to, say, 12 gauge to save weight. The edge of a panel could also have been folded back on itself. I'll be fascinating to see what they've done when all engineering, manufacturing, and economic factors were considered.
There's no evidence of this being changed. None.


Maybe it is, or maybe it isn't, but it could be scored to create crumple zones. At impact level forces, the metal has no problem folding. It needs that under support to connect to other panels.

-Crissa
See, I was thinking about that. With 90° folded edges around the perimeter of the panel, they probably wouldn't have needed the stamped sections for torsional rigidity. But I think Chris has got it right that since you need attachment points for things like latches and hinges and the LED strip. I also think that it still might be 3 mil which would allow them to reduce all aspects of those stamp sections. But it might not be man that tear down on this thing is just going to be so much fun for everybody
 

Cybergirl

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The question can’t be answered. Not enough information. You appear to assume that the heavier panels don’t offset a weight reduction in the castings and actually weigh more..

Let’s just throw out random numbers for an example.

A Generic brand truck has a 700# ladder frame. The body panels weigh 300#. The internal panels 100#. Frame to support cab and doors-250# Frames to support body panels 250# Truck structure weight is 1600# (no, these are not accurate weights, or even proportional, just making a point)

The CT has 700# of 3mm skin. The castings are 200# each for front and rear. (Remember, they are AL-You-Min-EE-UM) Mounting stuff is 200#. Inner panels are 100#. You now have a 1400# structure.

So the answer to the question is, if utilizing the 3mm SS allows you to reduce the same or a larger amount of weight elsewhere in the vehicle, then YES the benefits “outweigh” everything by providing a strength and possible weight ADVANTAGE. And even if it is a little more (which I doubt) I think there is a strength advantage that exceeds the weight advantage.



You’re beginning an argument with an assumption for the foundation.

Look all, if you think that the entire truck was going to use 3mm SS with no substructure, then you have no idea about metal strength. Like I said in another thread, EM said this was moving the structure to the outside LIKE A PLANE (which has a structure beneath the skin that supports the MAJORITY of the load) He never said it was only the skin, and he used a PLANE as his example, and not a CRAB! (Or a lobster, or a shrimp, or even a jumbo shrimp, or a Bubba Gump shrimp, or a king crab, or any other crustacean) If it were the skin alone, I’m not sure 10mm would be thick enough.

As for the frunk lid, even the sacred 3mm SS in a single sheet with no bends or creases is going to twist over 70+ inches without reinforcement of some kind. When I see that, I think of it being extra stout. And if there is power close of any kind, you’re going to want to make sure there is no twist from wind or whatever during closing.

Here’s a project for the class. Can you look at the CT without any bias and assume what was announced is what is inside, until proven otherwise? Can you listen to EM’s words exactly as he said them, not as you wanted to hear them? There’s a difference between “not later than” and “around”, just as there is a difference between “like a plane” and “like a crab”.
I'm not assuming anything, I'm suggesting that after 4 years since the original prototype was unveiled, a lot of engineering and economic analysis went into what we see today. The result of that intense effort is not fully known to us at this moment. No information has come confirming the use of 3mm SS, super strength glass, or an optional solar roof/tonneau cover. The vault was originally stainless steel, but doesn't appear to be now. The first giga castings for the Model Y were not deployed for another year after the Nov 19th unveiling of CT. Elon commented on how difficult they found it was to build an affordable Cybertruck. All I'm suggesting is that if it turns out that tradeoffs were made that reduced the thickness of the SS skins, or limited its application, don't be shocked.
 

PilotPete

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I'm not assuming anything,

All I'm suggesting is that if it turns out that tradeoffs were made that reduced the thickness of the SS skins, or limited its application, don't be shocked.
But you are assuming.

You are assuming that something HAD to be changed as a result of all that analysis. And that the assumed changes HAD to be in the skin thickness and structural design, as well as the glass. No information confirming the 3mm SS??? Other than the pictures? Well, there is no information coming out confirming it doesn’t have 496 V-8 either. But there has been no denial that it is NOT 3mm SS. Do they have to confirm everything it still has? If so, how often? There was never a promised solar roof or cover, and the vault cover is still there for all to see. The Gigacastings for the Y have nothing to do with the CT. Castings they got figured out for the CT. EM didn’t say he found it hard to build an affordable CT, he said it was going to cost more than the release amounts. He has also said this will be a technical flagship, and it will be next level. As for the bed, it has a coating over whatever is beneath the coating. Are you certain it isn’t SS? What evidence do you have for that? A bare SS bed would not be a good idea, and I think most people would get a rhino liner sprayed on right away anyway.

Don’t be a Debbie Downer here. Chin up and all that stuff. Don’t discount anything until there is real evidence of a change. (Like 5 seats) Then we can all lament what could have been.

Tesla Cybertruck Unassembled fender quarter panels stainless steel parts on Giga Texas factory floor 1696525847285
;)
 


Cybergirl

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But you are assuming.

You are assuming that something HAD to be changed as a result of all that analysis. And that the assumed changes HAD to be in the skin thickness and structural design, as well as the glass. No information confirming the 3mm SS??? Other than the pictures? Well, there is no information coming out confirming it doesn’t have 496 V-8 either. But there has been no denial that it is NOT 3mm SS. Do they have to confirm everything it still has? If so, how often? There was never a promised solar roof or cover, and the vault cover is still there for all to see. The Gigacastings for the Y have nothing to do with the CT. Castings they got figured out for the CT. EM didn’t say he found it hard to build an affordable CT, he said it was going to cost more than the release amounts. He has also said this will be a technical flagship, and it will be next level. As for the bed, it has a coating over whatever is beneath the coating. Are you certain it isn’t SS? What evidence do you have for that? A bare SS bed would not be a good idea, and I think most people would get a rhino liner sprayed on right away anyway.

Don’t be a Debbie Downer here. Chin up and all that stuff. Don’t discount anything until there is real evidence of a change. (Like 5 seats) Then we can all lament what could have been.

1696525847285.jpeg
;)
Wow, talk about thin skins.
 

PilotPete

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Wow, talk about thin skins.
Don’t worry, my skin is plenty thick.

Not sure where you took my response as personal, but it wasn’t. I don’t care enough about any forum, message board, bulletin board, bbs, whatever, to take it personally. I have been around this block more than once. I’m very unemotional and uncaring, just ask my ex, :devilish:

I’m just trying to make the point that too many people inject their own reasoning and then start talking about stuff that has been changed, and we don’t know that yet. Believe what you want, doesn’t matter to me. (I think I’ve said that before) If anything, I’m just offering a different perspective. You and everyone reading this are free as a bird to side where they will.
 

Coolbreeze704

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HaulingAss

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Well I'm glad we've finally managed to get you to eat your humble exoskeleton sandwich at least.

Previously, not so long ago, your position was that the CT was purely gutless and was all just held together by the skin of it's teeth. Lol.
That's your fantasy, and it's exactly what I was speaking of when I said you were not open to learning. The skin of the Cybertruck was never designed to provide the only structural strength as evidenced by the presence of driver and passenger doors because the relatively thin margins around them precluded not having additional structure beyond the stainless steel skin. It's only in your fantasy that I thought otherwise.

Make no mistake, the cold-rolled stainless steel skin is very structural and the chassis could not be loaded to its GVWR and driven over irregular ground without the stainless panels attached. It would fail in dramatic fashion.

So It's unclear what you appear to be crowing about. Me thinks the waiting game is affecting your psyche in an unflattering manner.
 

HaulingAss

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The question can’t be answered. Not enough information. You appear to assume that the heavier panels don’t offset a weight reduction in the castings and actually weigh more..

Let’s just throw out random numbers for an example.

A Generic brand truck has a 700# ladder frame. The body panels weigh 300#. The internal panels 100#. Frame to support cab and doors-250# Frames to support body panels 250# Truck structure weight is 1600# (no, these are not accurate weights, or even proportional, just making a point)

The CT has 700# of 3mm skin. The castings are 200# each for front and rear. (Remember, they are AL-You-Min-EE-UM) Mounting stuff is 200#. Inner panels are 100#. You now have a 1400# structure.

So the answer to the question is, if utilizing the 3mm SS allows you to reduce the same or a larger amount of weight elsewhere in the vehicle, then YES the benefits “outweigh” everything by providing a strength and possible weight ADVANTAGE. And even if it is a little more (which I doubt) I think there is a strength advantage that exceeds the weight advantage.



You’re beginning an argument with an assumption for the foundation.

Look all, if you think that the entire truck was going to use 3mm SS with no substructure, then you have no idea about metal strength. Like I said in another thread, EM said this was moving the structure to the outside LIKE A PLANE (which has a structure beneath the skin that supports the MAJORITY of the load) He never said it was only the skin, and he used a PLANE as his example, and not a CRAB! (Or a lobster, or a shrimp, or even a jumbo shrimp, or a Bubba Gump shrimp, or a king crab, or any other crustacean) If it were the skin alone, I’m not sure 10mm would be thick enough.

As for the frunk lid, even the sacred 3mm SS in a single sheet with no bends or creases is going to twist over 70+ inches without reinforcement of some kind. When I see that, I think of it being extra stout. And if there is power close of any kind, you’re going to want to make sure there is no twist from wind or whatever during closing.

Here’s a project for the class. Can you look at the CT without any bias and assume what was announced is what is inside, until proven otherwise? Can you listen to EM’s words exactly as he said them, not as you wanted to hear them? There’s a difference between “not later than” and “around”, just as there is a difference between “like a plane” and “like a crab”.
I think you misunderstood Crissa's point about the crab, and my point about the exoskeleton of an airframe being a composite structure. The point is, an exoskeleton does not have to be a single layer that is laminar, it can have it's own 3D structure within the exoskeleton. Exoskeleton denotes a structure that is exterior to the structure, not centralized like a traditional truck chassis that is body on frame.

And, yes, no one ever said the hood had to be 3mm thick, that depends upon the need for strength in that area.
 


JBee

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Do you need glasses?

I swear I saw a skinned Cybertruck BIW that held together just fine the other day.

How do you explain the right angle brackets and tiny little brackets on the top where the load would be, on the rear skin fender photos on this thread?

They have no capacity to transfer load into the skin, from between the cabin structure and the suspension, that is attached to the cast on the inside of the wheel arch. Remember all loads are carried by the suspension, except for crash ingress protection.

Even if there where more meaningful attachment points underneath that we can't see, it would only be in a physical position to attach to the cast, nothing more, not the cab or structural pack. So the cast would be supporting the rear fender, and not the other way around.

And all this ignores the fact that the cast is aluminium and the skin is stainless, and they have different thermal expansion properties that require the panels to be mounted on soft bushes, otherwise the panels would warp as soon as it sits in the sun. (ALU 17 - SS 21-24)

That's why it has right angle mounting brackets, so the thermal tension can be relieved between the BIW and the SS panel, by slightly bending the thin mounting bracket instead of the expanding and contracting length warping the SS panel. Note the thermal cycling would produce greater loads on the cast than loading the bed and lead to fractures over time.

And still, after a nearly a year of discussion, you haven't provided me with any explanation of where a load originates from on the skin. Is it from supporting all that ego you carry on that chip on your shoulder? ;) 😋 🤣
 

HaulingAss

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My prediction? Door skins and quarter panels will be thick. Frunk skin and front fenders will be a thinner gauge to allow for a crumple zone during a frontal collision.

Being a Tesla we know it’s going to achieve a 5-star crash test rating.
I think 3mm thick, cold-rolled ss will crumple just fine. In fact, it will reduce the need for as much supporting structure as would be necessary with thinner panels. That said, the exterior panels can only provide a fraction of the crash energy absortion because the strength it provides is so planar, in other words, so much stronger in some directions than others and it's shape is fixed by the shape of the truck, not the requirements of absorbing crash energy.

Crashes are very violent things and, even as strong as 3mm hardened ss is, it's not enough, there will be much more structure added for the pupose of absorbing more crash energy.

The hood may be thinner for reasons of weight and pedestrian safety, the hood is not structural to the chassis, it's attached with hinges and a latch. It can only contribute so much to absorbing crash energy. The only real reason to make it 3mm thick would be for resistance to hail damage, but I doubt that would pencil out economically. It would likely be better to have a thinner hood that could be replaced if it succumbed to hail damage than have 100's of 1000's of Cybertrucks carrying around an extra XX number of pounds, just incase it was subject to a hailstorm.

Tesla will use the thickness of steel that their engineering analysis informs is a beneficial use of materials. It may be the front quarter panels only need 2mm thick ss, while the doors and rear quarter panels get 3mm for the benefits they provide. We just don't know yet. What we do know are those quarter panels will be structural to the strength of the chassis. The door panels will be 3mm for the side impact protection and allowing the passenger safety compartment to be thinner (since the more rigid doors will transfer side-crash impacts more evenly over a larger area).
 

Crissa

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My prediction? Door skins and quarter panels will be thick. Frunk skin and front fenders will be a thinner gauge to allow for a crumple zone during a frontal collision.

Being a Tesla we know it’s going to achieve a 5-star crash test rating.
I think this is a fair guess, but I don't think it's impossible that the front is also the same thickness.

-Crissa
 

Sirfun

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When I look at those fenders I see how it could be fairly reasonable to get a replacement fender in the event of a crash. Also, those clip attachment points may be part of the crumple zones. They are the weakest link, and the fender just releases at the attachment point.
 

HaulingAss

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And still, after a nearly a year of discussion, you haven't provided me with any explanation of where a load originates from on the skin. Is it from supporting all that ego you carry on that chip on your shoulder? ;) 😋 🤣
The load on the skin is the direct result of the flexing of the rest of the structure, as it is loaded. Period.

I've explained this before, but you refuse to try to understand. That's how superior load and tow capacity is achieved. The structural skin stiffens the entire structure and causes localized loads on the underlying structure to remain more uniformly distributed around the underlying structure as the loading increases.

Put another way, as the loads on the chassis increase, generally through the transfer points of the suspension or the tow ball, the chassis flexes and the skin resists. This causes the skin to transfer forces to different areas of the underlying structure, making that structure do more with less. Unitized construction is much stronger (for the weight) but most unibody vehicles cannot take as much advantage of the strength of the skin because typical bodypanels, even on unibody vehicles, are made from metal that is too soft and too thin to assist much compared to the strength of a thicker, cold-rolled steel.

Without seeing more than we have (like the backside of the quarter-panels) we don't know how many load transfer points there are. And without doing a full engineering analysis, we don't know how many load transfer points per panel are needed. Or whether the panels use high-strength adhesives to transfer loads. I don't even know for sure what the purpose of the two visible tabs on the back of the quarter panel in the photos are for. If they are to transfer skin loads around the chassis, we don't know how many other tabs there are or where they are located. I do know that steel tabs that size can handle very significant loads in terms of stiffening the structure and reducing metal fatigue from repetitive load events.

I don't really expect you to try to understand, I'm writing this more for people who are actually curious about how Tesla plans to use the inherent strength of harder, stronger body panels to reduce the required weight of the rest of the chassis, without causing excessive flexing which, when done repeatedly, can induce metal fatigue. Spreading the forces around is an excellent strategy and will result in a very rigid chassis that doesn't weigh too much relative to it's abilities.
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