3d printed differentials

[Greatscott]

There will be a balance problem here, were the weight of your packs will slow you down, and going to a pack with less voltage will actually make you faster because of the weight you save. Also, in a straight line a 12S pack will be fine, but on a road course, you'll like run into issue. Also, the tuning is all wrong on solid axles for road use, it will be a hard row to how to get suspension performance on the track that comes anywhere close to a touring car. But, it will be interesting to see what you come up with.

Back to the diffs….
First, in the world of RC, when people start putting on ridiculous power, 4S +, they convert their spur over to metal, because the nylon spurs just can't handle the extra stress. It seems like in this process, you'll be bucking that trend. Second, I do not believe you will easily meet the required tolerances with an FDM printer, it will likely require a resin printer, and neither will get you close to what your after in a sub-$10k printer.

[jemelumadu2]

Originally Posted by Greatscott

There will be a balance problem here, were the weight of your packs will slow you down, and going to a pack with less voltage will actually make you faster because of the weight you save. Also, in a straight line a 12S pack will be fine, but on a road course, you'll like run into issue. Also, the tuning is all wrong on solid axles for road use, it will be a hard row to how to get suspension performance on the track that comes anywhere close to a touring car. But, it will be interesting to see what you come up with.

Back to the diffs….
First, in the world of RC, when people start putting on ridiculous power, 4S +, they convert their spur over to metal, because the nylon spurs just can't handle the extra stress. It seems like in this process, you'll be bucking that trend. Second, I do not believe you will easily meet the required tolerances with an FDM printer, it will likely require a resin printer, and neither will get you close to what your after in a sub-$10k printer.

I'm going with 1300 ovonic 100c 6s packs 2 for each motor is rated a 12s and 14000w. Next to the suspension i plan a active suspension that keeps the truck level at all times but doesn't sacrifice suspension damping. I know that I didn't mention this but I'm thinking about rear steering.
Lastly the diffs im going to make the gear teeth very thick and coat it in line x or go with a ball diff most likely test both.

Sent from my SM-G986U using Tapatalk

[Ninomaniac]

[jemelumadu2]

Originally Posted by Ninomaniac

Lol

Sent from my SM-G986U using Tapatalk

[QuesoDelDiablo]

While I fully encourage experimentation and innovation I also hate to see people waste their time and energy.

I don't have a ton of time to sit here typing so excuse the brevity of post.

3D printed plastics will absolutely not work for a 1/10 scale differential. As you're likely already aware nylon would be your best bet but even that wouldn't be adequate.

There's at least 2 major issues that come to mind right away - strength & heat.

Plastic isn't strong enough to support gear teeth at the loads you're going to be throwing at them and there's no way the output shaft will endure that kind of torque. I'd honestly be shocked if it went 1meter before if imploded.

And heat, at the speeds you're talking about there's going to be so much friction in the diff that plastic gears would probably melt.

And that's all after you've spent hours and hours on perfecting the design and refining it to be within the tolerances of what might actually work.

The advantage that Porsche has over you is size. The bigger parts are the stronger they are and the more heat they can tolerate. Oh yeah, and millions of dollars as well as the best engineers in the business.



Again, not trying to shit on your idea, but I think you'd be better off looking at other methods of reducing weight. Also consider that even if you did somehow miraculously make this work you're going to save a minimal amount of weight, I wouldn't be surprised if was only a savings of 20-30grams or less. Is 25grams worth the hours and hours of tedious design work?

[HumboldtEF]

I saw the new Cen F450 and thought of this thread, you're worried about weight and this thing is actaully listed a 5.5 lbs which is damn light. Seems like that could potentially be turned into something that may work with its open diffs and sway bars or atleast be fun while still being silly.

[jemelumadu2]

Originally Posted by QuesoDelDiablo

While I fully encourage experimentation and innovation I also hate to see people waste their time and energy.

I don't have a ton of time to sit here typing so excuse the brevity of post.

3D printed plastics will absolutely not work for a 1/10 scale differential. As you're likely already aware nylon would be your best bet but even that wouldn't be adequate.

There's at least 2 major issues that come to mind right away - strength & heat.

Plastic isn't strong enough to support gear teeth at the loads you're going to be throwing at them and there's no way the output shaft will endure that kind of torque. I'd honestly be shocked if it went 1meter before if imploded.

And heat, at the speeds you're talking about there's going to be so much friction in the diff that plastic gears would probably melt.

And that's all after you've spent hours and hours on perfecting the design and refining it to be within the tolerances of what might actually work.

The advantage that Porsche has over you is size. The bigger parts are the stronger they are and the more heat they can tolerate. Oh yeah, and millions of dollars as well as the best engineers in the business.



Again, not trying to shit on your idea, but I think you'd be better off looking at other methods of reducing weight. Also consider that even if you did somehow miraculously make this work you're going to save a minimal amount of weight, I wouldn't be surprised if was only a savings of 20-30grams or less. Is 25grams worth the hours and hours of tedious design work?

For the load on the plastic I'm planning on thick tooth, helical plastic gears coated in bed liner. The filament i want to use melting point is 230c and another filament is 180c there is going to be a temp sensor in the differential housing so if temps go near 150c I can always use a fan or switch to a metal housing. Personally I think anything is worth it to save weight even if it's 25grams for me its a achievement for my build. And everyone thinks it won't work so that's a bigger achievement.

Sent from my SM-G986U using Tapatalk

[jemelumadu2]

Originally Posted by HumboldtEF

I saw the new Cen F450 and thought of this thread, you're worried about weight and this thing is actaully listed a 5.5 lbs which is damn light. Seems like that could potentially be turned into something that may work with its open diffs and sway bars or atleast be fun while still being silly.

Yea it looks good tho

Sent from my SM-G986U using Tapatalk

[Greatscott]

Originally Posted by jemelumadu2

For the load on the plastic I'm planning on thick tooth, helical plastic gears coated in bed liner. The filament i want to use melting point is 230c and another filament is 180c there is going to be a temp sensor in the differential housing so if temps go near 150c I can always use a fan or switch to a metal housing. Personally I think anything is worth it to save weight even if it's 25grams for me its a achievement for my build. And everyone thinks it won't work so that's a bigger achievement.

Sent from my SM-G986U using Tapatalk

I hate to poke you in the eye brother, but what you are saying really doesn't make that much sense... Don't get me wrong, we love new thoughts and ideas for our hobby, and we love to be proven wrong, but it doesn't seems like all of the ducks are lining up here...

230C isn't that hot for filaments, in fact, it is right in the comfort zone for most of the common ones, including PLA, PETG, and ABS.... the exact ones that absolutely will not withstand the stress of 3S power, to say nothing about 12S.

How will coating the gears with bed liner help? That is not a smooth coating, it will increase weight, cause a lot more friction, and screw up the gear tolerances. If anything, they should be coated with a thin high temp polymer or ceramic coating.

I am very impress with the fine detail my printer can print, but, FDM has its limits. The print orientation will be key, to get the most strength out of the gear you'll have to print it vertical, or at a 45* angle, printing them flat will put the layers in line with the direction of stress, which makes for a weak part.

[jemelumadu2]

Originally Posted by Greatscott

I hate to poke you in the eye brother, but what you are saying really doesn't make that much sense... Don't get me wrong, we love new thoughts and ideas for our hobby, and we love to be proven wrong, but it doesn't seems like all of the ducks are lining up here...

230C isn't that hot for filaments, in fact, it is right in the comfort zone for most of the common ones, including PLA, PETG, and ABS.... the exact ones that absolutely will not withstand the stress of 3S power, to say nothing about 12S.

How will coating the gears with bed liner help? That is not a smooth coating, it will increase weight, cause a lot more friction, and screw up the gear tolerances. If anything, they should be coated with a thin high temp polymer or ceramic coating.

I am very impress with the fine detail my printer can print, but, FDM has its limits. The print orientation will be key, to get the most strength out of the gear you'll have to print it vertical, or at a 45* angle, printing them flat will put the layers in line with the direction of stress, which makes for a weak part.

The melting point for most filaments is around 220c even abs's melting point is 120c. Coating the gears in bed liner would hold the teeth together if it breaks but I would consider polymer or ceramic coating.

Sent from my SM-G986U using Tapatalk

[Greatscott]

I'm out... Recommendations requested, recommendations received, it is up to you to process the advice you have requested and proceed accordingly.

[jemelumadu2]

Originally Posted by Greatscott

I'm out... Recommendations requested, recommendations received, it is up to you to process the advice you have requested and proceed accordingly.

Yes sir

Sent from my SM-G986U using Tapatalk

[CNCist]

I know I'm harping on a beaten thread here. If you dont feel like reading a semi-rant, shear strength is the problem not heat. Make the gears big.

No plastic known to man will hold up as a differential, i know it was said porche 3d printed pistons, but thats rough metal with a final CNC portion to the process.

Heat in the plastic isn't the big problem, it's shear strength. If heat was a problem in a diff then carbon ceramic gears would be a thing. Keep in mind real diffs have oil to cool them down, we only have some grease, and grease doesn't add much benefits to cooling.
Its plastic, definition of plastic is that its maleable.

It is POSSIBLE, the density, and size you would have to make it would defeat the purpose. So ill leave on that note, work around shear strength of the material you would use and design around that.

[ScaleLifeNewbie]

Here to resurrect an old thread! How’d it go? Did the printed gears work?


Sent from my iPad using Tapatalk

[Voodoobrew]

Just reading this, but if you want to shave some weight I would just run one motor. A larger BLDC outrunner will produce more power with less weight. Team Brood make some long outrunners that should have crazy power density. or Just a larger sensored motor.
I am not aware of any reason why a dual motor setup would ever perform better except for independently modulating axle speeds.

[Greatscott]

Originally Posted by Voodoobrew

Just reading this, but if you want to shave some weight I would just run one motor. A larger BLDC outrunner will produce more power with less weight. Team Brood make some long outrunners that should have crazy power density. or Just a larger sensored motor.
I am not aware of any reason why a dual motor setup would ever perform better except for independently modulating axle speeds.

Dunno… I would like to see what he came up with and how it worked out. But, a lot of what he said just does not make that much sense. He is trying to shave milligrams off of the diffs, but is throwing the whole mess under a 12S pack? Active suspension? The weight cost of that alone would make any weight saving in the diffs moot.

I get the idea of doing something different to prove a point. This is a big reason I turned a Slash into track thoroughbred. It was awesome to see the Ofna, Losi and AE drivers' faces when they found out their race-bred SCT just got beat by a Slash. But, honestly, if I raced SCTs again, I would just buy one of the race-bred trucks, it would save a lot in both money and time. But, something tells me that a solid axle portalled 6x6 will be hard pressed to even get near the performance of an on-road factory racer. I could be wrong, but I doubt it....

[MOguy]

Originally Posted by jemelumadu2

I believe that if I get this light enough.

Sent from my SM-G986U using Tapatalk

Of all the places to save weight this is not one of them. You want weight low. The Diff is pretty low.

If you want to lower your center of gravity you need to shed every single once you can ABOVE the axles. You don't need allot of weight in your axles if you shed every single ounce you can above them but you still need weight in the axles.

[jemelumadu2]

Originally Posted by Greatscott

Dunno… I would like to see what he came up with and how it worked out. But, a lot of what he said just does not make that much sense. He is trying to shave milligrams off of the diffs, but is throwing the whole mess under a 12S pack? Active suspension? The weight cost of that alone would make any weight saving in the diffs moot.

I get the idea of doing something different to prove a point. This is a big reason I turned a Slash into track thoroughbred. It was awesome to see the Ofna, Losi and AE drivers' faces when they found out their race-bred SCT just got beat by a Slash. But, honestly, if I raced SCTs again, I would just buy one of the race-bred trucks, it would save a lot in both money and time. But, something tells me that a solid axle portalled 6x6 will be hard pressed to even get near the performance of an on-road factory racer. I could be wrong, but I doubt it....

Yeah u wrong


Sent from my SM-G986U using Tapatalk

[Greatscott]

Originally Posted by jemelumadu2

Yeah u wrong


Sent from my SM-G986U using Tapatalk

Proof?

I mean, its rare, but I do miss the mark from time to time. This whole thread seems like you REALLY wanted us to agree with you about the printed diffs, but none of us have. To put it bluntly, this is the point where you need to put up or shut up; lets see some video of this TRX6 spanking on road sedans.

[Tossedman]

Not sure about 12s but these guys 3d print the whole truck (except tires). So someone's doing it. Give it a try and report back. It's those that think outside the box that push development. There's also lots of failures to learn from along the way.