heinzboehmer's 2002 Topaz 6MT Coupe

[bavarian3]

Update from the manufacturer:



So cool.

Now just have to wait for them to get to me. I'm excited!

you're the mad scientist. this is awesome

[heinzboehmer]

Man, we're really living in the future.

Right? I'm constantly blown away that regular consumers can just do this type of thing now.

That was fast. Protolabs or somewhere else? I want to re-design all of this myself but ultimately I guess I'll just copy your stuff 1:1.

Got these through Craftcloud. 3DPnxt is the manufacturer making them.

And go for it! Would love to see others iterate on this design. The original CAD document is linked in the documentation I wrote up (https://drive.google.com/corp/drive/...ib65e2dj8d9FKH). It's got a bunch of scans and other references that will likely make your life easier if you want to redesign it

[discoelk]

That was fast. Protolabs or somewhere else? I want to re-design all of this myself but ultimately I guess I'll just copy your stuff 1:1.

[Bry5on]

Man, we're really living in the future.

Many No Longer Available parts almost no longer matter

[0-60motorsports]

Update from the manufacturer:



So cool.

Now just have to wait for them to get to me. I'm excited!

Beautiful

[Obioban]

Man, we're really living in the future.

[heinzboehmer]

Update from the manufacturer:



So cool.

Now just have to wait for them to get to me. I'm excited!

[heinzboehmer]

The three pockets around the bolt holes would need to go. The threaded insert may not fit and probably want some material there to take up anu torque stresses. The others aren't an issue as far as releasing the part.

Yep! Those three pockets are gone in the carbon version.

But cool, I'll get these printed in plastic and sent over to you. No rush or anything, just think it's cool to have some material choices.

[bigjae46]

Let me know what you think of the manufacturability of the design bigjae46

The three pockets around the bolt holes would need to go. The threaded insert may not fit and probably want some material there to take up anu torque stresses. The others aren't an issue as far as releasing the part.

[heinzboehmer]

Never knew about draft angles until I watched this video:

That's exactly the scenario I want to avoid

3 degrees is the good rule of thumb for mold release draft angles. It’ll be cool to see both options! You’re making me want to swap out the Slon brace to make maintenance easier.

Hell yeah! It is quite nice to be able to remove only a few components to get to the engine. Still a bit finicky to deal with the cabin air filter plastics, but I don't think there's a good way around that with how tightly everything is packaged back there.

Removing the Slon firewall mount point sounds like a huuuuge pain though.

The pockets just need to be less than 90 degrees to aid in the release. Maybe 87-88 degrees? It is a compression mold so the pockets are fine except for the smallest pocket near the bolt hole. I can still work around it but that one would be a pain.

Had a go at this and I think all of the pockets on the brace pickup points are gonna have to go for the carbon version. It's kinda hard to show in pictures, but the issue comes from the fact that the three mounting faces are at completely different angles to one another.

Hopefully this is appreciable in the following pics of the 3D printed aluminum version.

Viewing normal to the strut tower mounting surface:



Viewing normal to the stock strut bar mounting surface:



Viewing normal to the E86 brace mounting surface:



For the CF version, I modeled the pockets so that they're all normal to the strut tower mounting surface, since I think that makes the most sense. Unfortunately, after making the pockets at the brace pickup point normal to the strut tower surface AND modifying them so that there's still enough wall thickness around the fastener holes, they become too small to be practical for manufacturing.

I guess I could make ALL the pockets normal to some other surface (e.g. the stock bar mounting surface), but probably not worth the hassle. The volume of the pockets around the brace pickup points in the aluminum versions is ~15 cm3, which would roughly translate to tens of grams in CF. I bet that would be even less once you take into account the now-crooked pockets in the strut tower mounting surface.

Anyway, here's what I came up with for CF. 3 deg draft angle added to all the surfaces that are normal to the strut tower mounting surface (hard to tell, but trust me, the angles are there):



Let me know what you think of the manufacturability of the design bigjae46

Incidentally, I noticed this small oversight in the design I sent out to manufacture:



Min wall thickness there is 0.6 mm, which is not ideal. Fortunately the orthogonal surfaces are more than thick enough, so it doesn't actually impact the strength of the part:



I've since fixed this problem area in the CAD for both the aluminum and CF versions.

I did also try reaching out to the manufacturer to get the fixed version manufactured instead, but I was too late. Oh well. Again, strength of the part isn't affected, so as long as it prints out nicely (i.e. no holes), I'll be happy.

[Slideways]

Never knew about draft angles until I watched this video:

[Bry5on]

3 degrees is the good rule of thumb for mold release draft angles. It’ll be cool to see both options! You’re making me want to swap out the Slon brace to make maintenance easier.

[bigjae46]

Down! You think the pocketed version would lend itself well to being made in CF? Not sure if the features are too small/pointy to get a nice part from. I can add a small draft angle to the ribs to aid in mold release, but maybe it's simpler for you to work with the non-pocketed part.

The pockets just need to be less than 90 degrees to aid in the release. Maybe 87-88 degrees? It is a compression mold so the pockets are fine except for the smallest pocket near the bolt hole. I can still work around it but that one would be a pain.

[heinzboehmer]

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.

Down! You think the pocketed version would lend itself well to being made in CF? Not sure if the features are too small/pointy to get a nice part from. I can add a small draft angle to the ribs to aid in mold release, but maybe it's simpler for you to work with the non-pocketed part.

[heinzboehmer]

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.

I choose a TPMS surface as a proof of concept because the negative volume in there is continuous, which means the powder can be removed post-print. Specifically went with gyroid because it's used everywhere in FDM printing and the wide availability of 3D models online (even the wikipedia article has one) made it easy to implement in Blender.

If I were to actually go this route, I would likely choose something more like a skeletal, D type TPMS surface. Stiffness to weight is better than gyroid and it uses slightly less material for the same volume. Skeletal would make post processing easier as well.

There's other surfaces with continuous negative volumes, but the TPMS surfaces seem to have attracted the most research for use in materials (NASA has done a bunch), so there's less uncertainty with them. This route involves sitting down and figuring out how to mathematically generate the surface in Blender/Python though, sooo I didn't spend any time on it