heinzboehmer's 2002 Topaz 6MT Coupe

[bigjae46]

You know, I think this would be a good use case for the material. I'm still a bit worried about it shattering under high impacts, but that might not be a real concern with the load that these will see.

That being said, I really want to try the 3D printed metal thing, so gonna try aluminum first. And as mentioned earlier, I'm a sucker for maximum OE-ness and the texture of the 3D printed parts should match the OE parts quite nicely.

Carbon fiber in general has better material toughness than aluminum...not sure about forged carbon. Send me a set of 3D prints and I can make some! Would need a base piece that the part will sit in, has a flat bottom with a slight draft angle on the side to aid in release.

Or let me know how much chopped carbon you need to DIY it.

[Obioban]

Even if you go through with an infill, I’d think not gyroid? It’s optimized around strength while not shaking the printer— which is of no value here.

[heinzboehmer]

Busy week, so slower progress, but I did manage to find the time to get the weight savings features modeled in.

Had to learn some basic blender skills for the gyroid infill version. Hollowing the part out in parametric CAD was easy enough, but modeling the infill proved to be too much. Here's some Blender screenshots:





As cool as this seems, I don't think I'm gonna go forward with this as the final design. Seems like a bit of a pain to post-process and, crucially, I can't run FEA on meshes. I'm super tempted to lump one of these into my real order and run it just as an experiment, but we'll see.

So with the gyroid version off the table, pockets were next. Thankfully these were parametric CAD-able:




Just like before, the analysis on the version with the bosses does not close with the brace-buckling load. And just like before, not concerned. Analysis on the other version looks good.

Weight for the two no bosses, pocketed brackets made out of AlSi10Mg should be around 730g (+ weight of the studs). Stock brackets are 612g all in, so not bad at all. Muuuch better than the 1869g (!) for the sheet metal versions.

Worth pointing out that the pocketed versions are specifically made to be 3D printed. A 5 axis CNC might be able to get in there, but they are not designed for that, so it would likely be expensive. Any manufacturing method that involves a mold will for sure not work, since the draft angles are all wrong. Should be fairly easy to fix the drafts, but I didn't want the extra weight.

Just do pockets. The powder is packed in there and very hard to remove.

Also, stealthy is the way for sure. Cover carbon stuff in paint too

Yeeeah, I was stubborn with the gyroid version, but ultimately reached the same conclusion.

IMHO it's easy to make something that looks different, especially when adding/changing functionality. It's much trickier generally to add functionality while keeping the same packaging. That's exactly what I admire so much about this solution, as you say, unless someone was really looking they'd never notice it wasn't original, to do that, while also achieving the necessary functional requirements, is very cool.

I ordered a pair of second hand Z4 braces today

Hell yeah! That's exciting. I'll get these 3D printed brackets ordered and stress tested very soon.

It's great work. I was just curious as functionally it's fairly simple part but becomes quite complex with the OE cast (off chance that it's forged? I haven't looked that closely) design.

They look cast. Funnily enough, getting the angles and interfaces between the two brace pickup points correct was more work than recreating the stock bracket geometry.

Carbon fiber bro...

You know, I think this would be a good use case for the material. I'm still a bit worried about it shattering under high impacts, but that might not be a real concern with the load that these will see.

That being said, I really want to try the 3D printed metal thing, so gonna try aluminum first. And as mentioned earlier, I'm a sucker for maximum OE-ness and the texture of the 3D printed parts should match the OE parts quite nicely.

[Obioban]

You know, a friend was just telling me the other day that it's hard for her to comprehend why I would spend so much time designing something just to make it look like I didn't change anything at all. And to be honest, she has an excellent point.

But there's just something I find so cool about the stealthiness of this. It's a significant upgrade over stock, but it's invisible to anyone who doesn't know exactly what to look for.

Same reason why I painted my 996 calipers matte black and went with no decals. Guess my brain is just wired weird

100% agreed.

IMO the best mods are the ones where someone who isn't intimately familiar with the car can't tell what is stock and what is aftermarket.

[bigjae46]

Now, the big question is fatigue. No good way to model this, but the mounts will eventually fatigue because they'll be made of Aluminum. It's just a matter of how fast that happens. Hopefully not until the end of the cars service life!

I think it's time to stop messing around and just get these parts ordered. I'm running analyses with made up loads, which is unlikely to get me anywhere useful. Also, I've been thinking and, surprisingly, I don't think I care if these parts fail? They're dead easy to swap out, the price of manufacturing is super affordable and I've been dying to give metal 3D printing a shot. If they do fail, there's always CNC 7075 or printed Titanium

Carbon fiber bro...

[discoelk]

It's great work. I was just curious as functionally it's fairly simple part but becomes quite complex with the OE cast (off chance that it's forged? I haven't looked that closely) design.

[karter16]

But there's just something I find so cool about the stealthiness of this. It's a significant upgrade over stock, but it's invisible to anyone who doesn't know exactly what to look for.

IMHO it's easy to make something that looks different, especially when adding/changing functionality. It's much trickier generally to add functionality while keeping the same packaging. That's exactly what I admire so much about this solution, as you say, unless someone was really looking they'd never notice it wasn't original, to do that, while also achieving the necessary functional requirements, is very cool.

I ordered a pair of second hand Z4 braces today

[Bry5on]

Just do pockets. The powder is packed in there and very hard to remove.

Also, stealthy is the way for sure. Cover carbon stuff in paint too

[heinzboehmer]

It is solid, no infill fanciness

Bummer. I wonder if I can model the infill in and have them manufacture it like that.

I could use a continuous volume infill like gyroid and add a couple drain holes to drain the powdered metal that will get trapped when printing.

Maybe I'm trying to approach the problem in too much of an FDM way and I should just do pockets instead? I don't know.

I'll give the modeled gyroid infill strategy a shot just cause it sounds novel and neat. Will report back once I've given up and decided to go back to the tried and true weight saving strategies.

Any reason you want to make them so similar to the OE part?

You know, a friend was just telling me the other day that it's hard for her to comprehend why I would spend so much time designing something just to make it look like I didn't change anything at all. And to be honest, she has an excellent point.

But there's just something I find so cool about the stealthiness of this. It's a significant upgrade over stock, but it's invisible to anyone who doesn't know exactly what to look for.

Same reason why I painted my 996 calipers matte black and went with no decals. Guess my brain is just wired weird

[discoelk]

Any reason you want to make them so similar to the OE part?

[Bry5on]

Infill!

But actually, I have no idea how that works when getting a part printed in metal...

It is solid, no infill fanciness

[Obioban]

Oh come on, you've got to pocket them for weight savings!! You're killing me smalls

lol. Read my mind.

[heinzboehmer]

Oh come on, you've got to pocket them for weight savings!! You're killing me smalls

Infill!

But actually, I have no idea how that works when getting a part printed in metal...

[Bry5on]

Oh come on, you've got to pocket them for weight savings!! You're killing me smalls

[heinzboehmer]

This is great, flat stock brackets would be great, I would love some of those!!
Just as long as the bar would still clear, I'll do some measurements to get a rough idea.

I don't have any information to prove otherwise but I would think the completely flat surface would protect the towers better than the OEM setup with the much smaller surface area.

I would like to go all the way someday and triangulate but I think my D.S tower has moved unfortunately. I hope to find that I am wrong there.

Those brackets with the flat bottom are identical to stock, except for the flat bottom, of course. The bar will stay in the exact same spot where it is now, so should clear just fine!

Let me know if you want the .step files. Looking like ~$150 per side for printing the flat bottom stock brackets in aluminum: