6 ms·

Where's the evidence of danger?

whymauri 6y ago
Laziness at one point of a design process could imply a theme, is what I think they're getting at. I still think about this Twitter thread, for example: https://twitter.com/atomicthumbs/status/1032939617404645376 https://twitter.com/atomicthumbs/status/1032939617404645376
- jrootabega 6y ago
  So it's the brown m&ms
xattt 6y ago
It’s indirectly implied with the juxtaposition of cooling, wood and Home Depot in one sentence.
happytoexplain 6y ago
Surely the burden of proof is opposite for manufacturers of big consumer machines? I'm not sure how regulation works here.
- gpm 6y ago
  I think there are two sets of burdens of proof here. The engineer who made this decision has a burden of proof to his boss (and maybe regulators, don't know) to show that this is safe. The random internet commenter suggesting it is unsafe has a burden of proof to show that either it is actually unsafe, or that at least that Tesla didn't internally meet it's burden of proof.
- sokoloff 6y ago
  This seems like a perfectly good solution to me. You're trying to stabilize the cooler, spread the clamping force, and avoid sharp edges and wear. The part chosen seems perfectly suitable for that, albeit slightly unconventional looking. (I say this as someone who is short $TSLA right now [and a non-practicing Mech E]; this looks perfectly reasonable to me.)
  - jeffbee 6y ago
    I agree that if you dug into the engineering the math probably works[1]. It's just a weird culture to be out on the floor substituting random materials in a load-bearing, if perhaps not life-safety-critical, part. 1: Compressive strength of wood perpendicular to the grain varies but you can estimate with a healthy safety margin about 200 PSI. 100x - 1000x weaker than metals, but still not zero.
    - sokoloff 6y ago
      I (pretty strongly) suspect that engineers were involved, rather than this being an assembly line worker floor-level decision. The same company that erected a factory-in-a-tent (unconventional but also appropriate) to hit aggressive production targets seems like one that would consider and execute appropriate but unconventional substitutions.
    - hcknwscommenter 6y ago
      "Compressive strength of wood . . ." I guarantee you that the materiel is not "wood" and is indeed much weaker in all relevant parameters. And I suspect that no one at TESLA has any real handle on the compressive strength of this material.
      - jeffbee 6y ago
        You think so? MDF is stronger than wood in compression and isotropic which is nice.
  - themaninthedark 6y ago
    The standard pieces have more surface area than the wood edge trim, I doubt the clamping force is spread as much.
gerbler 6y ago
The fact that it's needed in a precisely made complex machine, suggests something is wrong. I think a better question is where's the evidence this is safe?
- dragonwriter 6y ago
  > The fact that it's needed in a precisely made complex machine The fact that it's needed in a complex machine shows that it's not one that is precisely made, I would think.
SideburnsOfDoom 6y ago
Where's the evidence of safety?
Nition 6y ago
Well, the even more basic plastic corner piece used on this person's one in the same thread has started to break: https://teslamotorsclub.com/tmc/posts/4976933/ https://teslamotorsclub.com/tmc/posts/4976933/ > The LCC (Liquid Cooled Condenser) was probably not designed to be mounted horizontally so they added the cinch strap which needed edge protection to prevent crushing the condenser contact surfaces... enter corner molding from Home depot. Will be interesting to see if that corner molding holds up over time. The cheap stuff is mostly air, the better stuff has more plastic content. If you do 3D printing you know what "fill" means..... look how the strap crushed the plastic corner molding in this photo. If it crushes/compresses it more over time.. the strap will be lose and the condenser will shake/possibly stress crack at it's base? I did like this sarcastic response to it: > See OP??? The Home Depot wood trim on yours exceeds the factory spec! At least it will not get crushed by the strap because it's not cheap plastic corner trim from Lowe's like others have.
themaninthedark 6y ago
Looking at the part and where it is used, I would guess that the purpose is strain relief to keep the strap off the metal assembly. There are a couple things I notice when I look at the shortage workaround. 1.Fake wood pieces are longer than the proper plastic piece(Why?). 2.Fake wood pieces are wrapped in green tape, proper plastic piece is not.(Speculation, metal strap edge cuts into fake wood. If so, how long will tape hold up with vibration?) 3.At least 2 different materials were used as a substitute, are these materials equivalent? Is there confidence in the supply chain of these parts that there was not a bad batch that will fail under heat or stress? 4.Overall quality of workmanship. In two of the 3 pictures, the lengths of the 2 fake wood pieces do not match. This points more to a production line workaround than a sanctioned fix. 5.The proper plastic piece has a larger area in contact with the cooler assembly than the fake wood pieces. This will result in more force being transferred to a point and possibly resulting in crushing damage to the assembly. I work in a facility that assembles heavy off road equipment, we do sometimes use BOM parts if we encounter a shortage. Unless the part is identical in fit and function i.e. using a slightly oversized hose clamp, we will go back and rework the machine so that it conforms to our quality standards before we ship it. If I was tasked with coming up with a replacement for the missing part, I would propose something like this: https://www.grainger.com/product/GRAINGER-APPROVED-Edge-Protector-2CXP7 https://www.grainger.com/product/GRAINGER-APPROVED-Edge-Prot... Rather than use something that looks obviously out of place.
awad 6y ago
People have had their car AC blowing out hot air which can be annoying to downright dangerous in parts of the country. At least one has had his car refuse to start due to battery overheating. I can't for sure say THIS is the reason for any of those issues or that THIS is a dangerous bit unto itself but HVAC generally for an electric car is pretty important to get right given the battery powered system and this particular model's new "Octovalve" Thermal Management setup.

Laziness at one point of a design process could imply a theme, is what I think they're getting at. I still think about this Twitter thread, for example: https://twitter.com/atomicthumbs/status/1032939617404645376 https://twitter.com/atomicthumbs/status/1032939617404645376

jrootabega 6y ago
So it's the brown m&ms

xattt 6y ago

It’s indirectly implied with the juxtaposition of cooling, wood and Home Depot in one sentence.

happytoexplain 6y ago

Surely the burden of proof is opposite for manufacturers of big consumer machines? I'm not sure how regulation works here.

gpm 6y ago
I think there are two sets of burdens of proof here. The engineer who made this decision has a burden of proof to his boss (and maybe regulators, don't know) to show that this is safe. The random internet commenter suggesting it is unsafe has a burden of proof to show that either it is actually unsafe, or that at least that Tesla didn't internally meet it's burden of proof.
sokoloff 6y ago
This seems like a perfectly good solution to me. You're trying to stabilize the cooler, spread the clamping force, and avoid sharp edges and wear. The part chosen seems perfectly suitable for that, albeit slightly unconventional looking. (I say this as someone who is short $TSLA right now [and a non-practicing Mech E]; this looks perfectly reasonable to me.)
- jeffbee 6y ago
  I agree that if you dug into the engineering the math probably works[1]. It's just a weird culture to be out on the floor substituting random materials in a load-bearing, if perhaps not life-safety-critical, part. 1: Compressive strength of wood perpendicular to the grain varies but you can estimate with a healthy safety margin about 200 PSI. 100x - 1000x weaker than metals, but still not zero.
  - sokoloff 6y ago
    I (pretty strongly) suspect that engineers were involved, rather than this being an assembly line worker floor-level decision. The same company that erected a factory-in-a-tent (unconventional but also appropriate) to hit aggressive production targets seems like one that would consider and execute appropriate but unconventional substitutions.
  - hcknwscommenter 6y ago
    "Compressive strength of wood . . ." I guarantee you that the materiel is not "wood" and is indeed much weaker in all relevant parameters. And I suspect that no one at TESLA has any real handle on the compressive strength of this material.
    - jeffbee 6y ago
      You think so? MDF is stronger than wood in compression and isotropic which is nice.
- themaninthedark 6y ago
  The standard pieces have more surface area than the wood edge trim, I doubt the clamping force is spread as much.

gerbler 6y ago

The fact that it's needed in a precisely made complex machine, suggests something is wrong. I think a better question is where's the evidence this is safe?

dragonwriter 6y ago
> The fact that it's needed in a precisely made complex machine The fact that it's needed in a complex machine shows that it's not one that is precisely made, I would think.

SideburnsOfDoom 6y ago

Where's the evidence of safety?

Nition 6y ago

Well, the even more basic plastic corner piece used on this person's one in the same thread has started to break: https://teslamotorsclub.com/tmc/posts/4976933/ https://teslamotorsclub.com/tmc/posts/4976933/ > The LCC (Liquid Cooled Condenser) was probably not designed to be mounted horizontally so they added the cinch strap which needed edge protection to prevent crushing the condenser contact surfaces... enter corner molding from Home depot. Will be interesting to see if that corner molding holds up over time. The cheap stuff is mostly air, the better stuff has more plastic content. If you do 3D printing you know what "fill" means..... look how the strap crushed the plastic corner molding in this photo. If it crushes/compresses it more over time.. the strap will be lose and the condenser will shake/possibly stress crack at it's base? I did like this sarcastic response to it: > See OP??? The Home Depot wood trim on yours exceeds the factory spec! At least it will not get crushed by the strap because it's not cheap plastic corner trim from Lowe's like others have.

themaninthedark 6y ago

Looking at the part and where it is used, I would guess that the purpose is strain relief to keep the strap off the metal assembly. There are a couple things I notice when I look at the shortage workaround. 1.Fake wood pieces are longer than the proper plastic piece(Why?). 2.Fake wood pieces are wrapped in green tape, proper plastic piece is not.(Speculation, metal strap edge cuts into fake wood. If so, how long will tape hold up with vibration?) 3.At least 2 different materials were used as a substitute, are these materials equivalent? Is there confidence in the supply chain of these parts that there was not a bad batch that will fail under heat or stress? 4.Overall quality of workmanship. In two of the 3 pictures, the lengths of the 2 fake wood pieces do not match. This points more to a production line workaround than a sanctioned fix. 5.The proper plastic piece has a larger area in contact with the cooler assembly than the fake wood pieces. This will result in more force being transferred to a point and possibly resulting in crushing damage to the assembly. I work in a facility that assembles heavy off road equipment, we do sometimes use BOM parts if we encounter a shortage. Unless the part is identical in fit and function i.e. using a slightly oversized hose clamp, we will go back and rework the machine so that it conforms to our quality standards before we ship it. If I was tasked with coming up with a replacement for the missing part, I would propose something like this: https://www.grainger.com/product/GRAINGER-APPROVED-Edge-Protector-2CXP7 https://www.grainger.com/product/GRAINGER-APPROVED-Edge-Prot... Rather than use something that looks obviously out of place.

awad 6y ago

People have had their car AC blowing out hot air which can be annoying to downright dangerous in parts of the country. At least one has had his car refuse to start due to battery overheating. I can't for sure say THIS is the reason for any of those issues or that THIS is a dangerous bit unto itself but HVAC generally for an electric car is pretty important to get right given the battery powered system and this particular model's new "Octovalve" Thermal Management setup.