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Edited Date/Time
6/14/2022 5:21am
It seems all the speculation and arguments about the range of the new Stark have overshadowed some of the other details of the bike... It's interesting that no one has noticed they're using a 3D printed top triple clamp on the bike.
We looked into this a couple years back, but the only viable material for 3D printing was titanium. By the time you add all the parts of the clamps that need to be there (fork tube clamps, steering stem area, bar mount area, etc.), then attach them to each other, even with minimal material, they ended up heavier than our machined aluminum clamps. So we abandoned the idea.
You can see the Stark integrates the top clamp and the bar mount into one piece. This is terrible for an ICE bike as the vibrations kill your hands. But an electric bike doesn't have this problem... Regardless, a solid bar mount sucks for absorbing track bumps and shock, though. I wonder if the bike pictured was a "show bike" or on all of the actual test bikes?
Manufacturing at volume makes 3D printing clamps difficult (expensive, time consuming), so it will be interesting to see what comes on the production bikes. It's also worth noting that the bottom clamp on the bike pictured is machined, which is what I would expect them to do (for manufacturing costs and time), plus the bottom clamp sees most of the load.
Anyway, just thought I'd point out an interesting detail that seems to have been missed so far (though I haven't been through all the reviews, so it may as well be out there).
We looked into this a couple years back, but the only viable material for 3D printing was titanium. By the time you add all the parts of the clamps that need to be there (fork tube clamps, steering stem area, bar mount area, etc.), then attach them to each other, even with minimal material, they ended up heavier than our machined aluminum clamps. So we abandoned the idea.
You can see the Stark integrates the top clamp and the bar mount into one piece. This is terrible for an ICE bike as the vibrations kill your hands. But an electric bike doesn't have this problem... Regardless, a solid bar mount sucks for absorbing track bumps and shock, though. I wonder if the bike pictured was a "show bike" or on all of the actual test bikes?
Manufacturing at volume makes 3D printing clamps difficult (expensive, time consuming), so it will be interesting to see what comes on the production bikes. It's also worth noting that the bottom clamp on the bike pictured is machined, which is what I would expect them to do (for manufacturing costs and time), plus the bottom clamp sees most of the load.
Anyway, just thought I'd point out an interesting detail that seems to have been missed so far (though I haven't been through all the reviews, so it may as well be out there).
Pinch bolt alert!
WeeoooWeeooWeeoooooooooo!
From what I've been reading it sounds like they're getting closer and closer to being able to print aluminum reliably. We actually had a few parts quoted in 3d printed aluminum, and while the material specs were really impressive, the cost was still orders of magnitude higher than would make sense for any production part. I don't know if it will ever truly become a viable manufacturing process at scale but the possibilities are fun to think about.
The Shop
On the printing of Metal thing, I'm currently seeing what sort of price I'd have to pay for the front of my Swingarms and the Bottom Bracket / Swingarm Pivot unit, and the Rear Axle Plate holders on the Bicycle frames I make. The first two are made of multiple parts and weldments, and take a Lot of time for me to make, the third; well, why not price them at the same time? There's an OZ company: https://www.spee3d.com/ that I'm getting some quotes from, and well, a few others around to try.
It would be quite a change for me, having fanatically made All of my frame parts for decades now myself, but it's getting down to what my time is worth, and making things easier for me. And, it probably wouldn't hurt to have something a bit 'Gee Wiz' for people to get excited over.........
It looked like a spiders web.. scary and only as good as the guy who X-Rays it.. will try and find pictures.
It is awesome to see it progress. About once per year I quote some tooling parts in 3d printed materials. Eventually it might make sense to print -> heat treat -> grind -> wire edm, effectively skipping the machining step (especially for parts with internal porting). But we’re not quite there yet.
Also, as far as I can tell, 3d printed parts have physical properties similar to cast (with possibly more cleanliness). So they’re still outclassed by most conventionally produced wrought materials.
Plastic is another story. I have all sorts of parts printed in Nylon 11 (either laser sinter or MJF) and they’re incredible. Basically full strength Nylon with 40% elongation at break. Reliably print down to .040” wall thickness with great resolution. It’s a godsend for making air blast manifolds, coolant nozzles, and robot grippers for high volume production.
So 3d printing presumably offers much less material usage than machining billet, how does casting compare? I would imagine you waste some material during casting, surely it's not excessive?
Can casting, 3D or machining be employed to optimize for smaller material use?
No next is energy... how much power is needed to print, cast or machine (and then recycle the waste) of a part?
It might be a while before you see them replacing forgings though. Grain structure still matters in some applications.
Casting and forging both have some waste as well with sprues, runners, risers, flash, etc. that need to be cut off (and recycled). But it's not nearly as much waste as machining. Additive (3D printing) has some waste, but it's minimal in comparison to other manufacturing techniques.
I haven't looked at energy costs or anything, aside from knowing what my electricity bill is. It doesn't jump through the roof when the machines are running or anything, though. Forging takes a lot of energy as well as casting. Likely more than machining, but that's just a semi-educated guess on my part. Don't forget that the forged and cast pieces need top be machined to final size on bores, threaded holes, etc. Casting and forging tooling is REALLY expensive too. Machined parts need fixturing, but that costs hundreds of dollars where forging dies and casting molds cost tens (or hundreds) of thousands.
3D printing doesn't require fixturing or tooling at all, but you may need a wire EDM to cut off the parts from the build platform or other fancy tooling depending on the printer and the part design needs. You still need to finish machine bores and threads on a printed part.
3D printing and "Generative Design" go hand in hand these days with generative design software able to output the resulting models directly to print. It's easy to tell if that's the case as you can almost always see the defects in the analysis constraints in the resulting design. Like the stress risers present everywhere the design material (the organic looking spider web material) meets the non-design material (fork tube and steering stem bores, etc.). In the case of the Stark clamp, it's most noticeable on the left side of the steering stem bore.
Our clamps and other parts are designed with generative design technology too (more specifically topology optimization, see: https://www.luxonmx.com/technology.html), but we're machining the parts instead of printing. So we can't just use the software's automated results to CAD features. We have to physically model the resulting design so it's machinable. That's why our clamps look a lot different from anyone else's, but they don't have the organic spider-web looking design of the straight to 3D print parts.
It will be interesting to see how the 3D printing technology develops. As soon as they develop an aluminum material with comparable properties to billet aluminum, we'll be able to leverage it in triple clamp design. Maybe by that time the costs will have come down to get it at a reasonable cost, but that's still a ways out I suspect.
Pit Row
I'm excited to see where this ends up in a few years, just like with plastic 3DP it's become a materials science race.
Formula D team's 3DP Inconel header -
https://www.motorsportmagazine.com/articles/motorcycles/motogp/the-big-mugello-motogp-surprise-ktms-comeback
Sometimes you see the material data for different directions (in-plane or in the build direction, Z) as the actual properties will change dependent on how the part is oriented. Here's some pretty generic data, though it doesn't list different values by direction:
https://www.forecast3d.com/wp-content/uploads/2018/01/Metal-Powders-SLM…
The material is only as good as the process, though. You (your printer, really) are the one "making" the material from the powder. So your laser must consistently and thoroughly bond each layer to each other, otherwise, you're going to end up with a bad part. I'd assume they have this pretty well sorted out by now, but it's certainly something I'd be leery of until it's really well proven. And your powder must be really clean and not contaminated. If the operator gets lazy and things get dirty, oxidized, mixed up, etc. then things can really go wrong that way too. But I'm betting advancements are being made to foolproof that area of 3D printing as well.
Every part you machine from 7075-T6 , the one thing you know is that the material is correct and certified (as long as you have the cert).
With additive, every grain of powder is a building block that has to be melted into place, and any impurity or void it a potential weak spot.
As you may have seen on Air Crash Investigation , a defect the size of a grain of sand, that wasnt picked up at Xray, caused an engine failure in the rear of a Tri-Star.
My last job we did 3D printing R&D , and it took as long to validate the print as it did to do it on some jobs..
Where these things arent structural, there is less of an issue, but every single part is a unique build, there is no place where you can say 'this one is right so i dont need to check that one'.. you cant validate it like a tool path.
Exhaust pipes dont matter, they have been using them for year, at least the stubs, i dont see the benefit of full pipes, but there must be one.
We had 3D printed Turbo waste gates in 2003 in WRC but they never made it onto the car because of the porosity issues of the early method.
https://www.athertonbikes.com/
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