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The Buchka 242 Fake Racecar

Red is the new purple. Just had the latest rev of the Stack circuit board delivered. It's got smattering of mods and simplifications. Fewer button inputs, larger mounting holes, two layer PCB instead of four, LDOs instead of switch mode regulators, software controllable CAN terminations, 5V level switching for the display, pinout that matches the stock Stack, improved microcontroller pin assignments, and I baked in the bodge wire changes I had to make on the previous version.

Oh, and the software has been updated so the CAN messaging, display page configs, and alarms are entirely defined with a text file that you load on to a micro SD card. No more recompiling to alter the setup.

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This thread was my first stop after my 6 year Turbobricks hiatus. Made me smile just like last time! Good stuff, love it.
 
This thread was my first stop after my 6 year Turbobricks hiatus. Made me smile just like last time! Good stuff, love it.

Thanks, Bob!

Mocked up the new driveshaft adapter today. It fits very nicely. This will let us run the standard Corvette torque tube input shaft, but with an exposed flange. The transmission will get a similar adapter dongus. At that point we can run a conventional driveshaft between the two. The rigid torque tube had to go since the Xtrac input shaft is much lower than the crank centerline of the engine.

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Exhaust manifolds just came out of the printer today. Total machine time was around 55 hours. They are Inconel 625 with 1mm walls, twin scroll collectors, and EGT ports.

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Very impressive and beautiful result. Does the 3D design program itself determine the most efficient composition/layout of the print surface or does the designer do that? 55 hours of machine time. Compared to a welded manifold not only a time consuming but also pretty expensive object, I guess. If I may ask, what amount should I roughly think of for only the 3D printing?
 
It’s amazing what DMLS can do. We’ve been running some dmls copper bus bars in custom e-motors and it always blows my mind to see how well dmls can come out with awkward metals like inconel and copper. Also, the machinability of it. We have several aluminum parts that are have machined faces and the porosity is nonexistent and better than most castings we get.
 
Thanks dudes. Karl and I are really excited to get these on the car

Very impressive and beautiful result. Does the 3D design program itself determine the most efficient composition/layout of the print surface or does the designer do that? 55 hours of machine time. Compared to a welded manifold not only a time consuming but also pretty expensive object, I guess. If I may ask, what amount should I roughly think of for only the 3D printing?

The entire process is very manual and can be quite time consuming. While modeling the part you have to keep the limitations of the printing process in mind and design the part accordingly. The manifolds took me two or three major revisions to finalize, so probably 30-40 hours of CAD. Preparation for the printing itself is also done mostly by hand in the slicing software. 55 hours was the total machine run time which is completely unattended.

Obviously the whole process costs a lot of time. In this case because the packaging was very tight and with the twin scroll v-band turbine housing it would have meant fabricating by hand would have been very time consuming as well.

The final cost ends up being less expensive than a fabricated manifold considering the material is Inconel 625.

It?s amazing what DMLS can do. We?ve been running some dmls copper bus bars in custom e-motors and it always blows my mind to see how well dmls can come out with awkward metals like inconel and copper. Also, the machinability of it. We have several aluminum parts that are have machined faces and the porosity is nonexistent and better than most castings we get.

Agreed, the process is very impressive. I'm simultaneously amazed at how fickle and sensitive it is. The machines are always almost-but-not-quite broken in some way or another.
 
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Agreed, the process is very impressive. I'm simultaneously amazed at how fickle and sensitive it is. The machines are always almost-but-not-quite broken in some way or another.
Interesting, do you think there are factors/influences that affect the machines that are not yet considered or understood? Does it work better on full moons? Could other electronics in the surrounding area be messing with stuff?
 
Is "the red" (looks like male / female spherical rod ends) the support of the turbo, besides the manifold?

I was thinking back to a car I saw years ago at the Baltimore GP. Supported from above with this structure...and I was thinking about what the difference would be between a pivoting support like this from above vs. holding up the turbo from the bottom. I don't recall seeing other examples of a pivoting support like that from underneath the turbo, so I was curious about how the turbos will be mounted on The Fake Racecar.

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If the engine is rigidly mounted to the chassis, is there any need to hang the support off the engine like that one above, or could you hang/support the turbo off one of the tubes of the chassis that's nearest the turbo?
 
Interesting, do you think there are factors/influences that affect the machines that are not yet considered or understood? Does it work better on full moons? Could other electronics in the surrounding area be messing with stuff?

Our former quality engineer was lead "Build Plate" engineer for a shop that only did DMLS. He was the guy that would position your models on the build plate to ensure it wouldn't collapse, or have weirdness during the process. He said that there are hundreds of variables that are still being found. At the time he left they were doing some in house R&D on electrostatic charges, chamber pressures, and the influence of contaminants to get list of problem/cause.
 
Our former quality engineer was lead "Build Plate" engineer for a shop that only did DMLS. He was the guy that would position your models on the build plate to ensure it wouldn't collapse, or have weirdness during the process. He said that there are hundreds of variables that are still being found. At the time he left they were doing some in house R&D on electrostatic charges, chamber pressures, and the influence of contaminants to get list of problem/cause.

Awesome. Thanks for the response. These are the things that tickle my brain.
 
Interesting, do you think there are factors/influences that affect the machines that are not yet considered or understood? Does it work better on full moons? Could other electronics in the surrounding area be messing with stuff?

The technology is still early in its development. A good example of how sensitive the machines are is that a loud stereo in the same room as the machine will vibrate the machine enough to leave visible artifacts on the surface of the parts.

Is "the red" (looks like male / female spherical rod ends) the support of the turbo, besides the manifold?

I was thinking back to a car I saw years ago at the Baltimore GP. Supported from above with this structure...and I was thinking about what the difference would be between a pivoting support like this from above vs. holding up the turbo from the bottom. I don't recall seeing other examples of a pivoting support like that from underneath the turbo, so I was curious about how the turbos will be mounted on The Fake Racecar.

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If the engine is rigidly mounted to the chassis, is there any need to hang the support off the engine like that one above, or could you hang/support the turbo off one of the tubes of the chassis that's nearest the turbo?

You are correct, that is the support bracket. The lower end of the rod end assembly will attach to the engine mount bracket. I don't have a ton of experience with designing turbo supports but all the people I know that are better at this than I am didn't have any issues with supporting it from the bottom. I tried packaging something that would hang the turbo instead but that area is so crammed full of stuff already it just wasn't practical.

You definitely want the support to be tied to the engine itself. Even with a rigidly mounted engine the suspension loads from driving will deflect the chassis enough to potentially cause issues if the hanger is on a chassis tube.

Our former quality engineer was lead "Build Plate" engineer for a shop that only did DMLS. He was the guy that would position your models on the build plate to ensure it wouldn't collapse, or have weirdness during the process. He said that there are hundreds of variables that are still being found. At the time he left they were doing some in house R&D on electrostatic charges, chamber pressures, and the influence of contaminants to get list of problem/cause.

This is consistent with my experience as well. The influence of all those factors are also material dependent, so what works for one nickel alloy won't translate to any others.
 
The machines are always almost-but-not-quite broken in some way or another.

Like most good Volvo 240s.

You definitely want the support to be tied to the engine itself. Even with a rigidly mounted engine the suspension loads from driving will deflect the chassis enough to potentially cause issues if the hanger is on a chassis tube.

Agreed, turbo support should be attached to the engine, ideally only the cylinder head. In addition to chassis deflection don't forget that the turbo will move with respect to both the engine and the chassis, due to thermal expansion of the exhaust manifold and turbine housing, and you'll also get displacement from vibration. Even if your hanger bracket is attached to the head alone, a strut with two rod ends to allow unconstrained lateral growth of the manifold is a must.
 
Got some additional printed parts that wouldn't fit with the manifolds. These are turbo oil drain flanges with support brackets built in. The hole in the bracket gets tapped to 1/4-28 and holds a rod end that runs down to the engine mount. We're having to support the turbos from the bottom since there's no room up top. I got a chance to program these parts for the printer and I'm happy to report that they came out as expected.

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Oh damn that's super cool! It's awesome to see 3D printed parts actually being used for the intended part application instead of a proof of concept or non-functional prototype.

Man I'd love to learn how to operate a DMLS machine. I currently work with carbon DLS machines. They're cool, but there's something extra cool about fusing metal dust into a solid.

It's interesting that they still need supports even while suspended in the powder. But I guess it makes sense since the metal parts are presumably heavier than their plastic counterparts in SLS machines
 
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