Scott Spark 1x10 lefty 18.98lbs (8572g)

[MattBeOne]

Shouldnt be too hard.
Look at your max power output and at which RPM this was. Then calculate the force on the pedal. Torque is this force times the crank arm length.
The force on the chainring tips would then be this torque multiplied with the outer diameter of the chainring (at the chain).

Something like this could give you a basic idea of the forces that are in play. Basic structural design should give you an idea of what thickness you need for chainring structure.

[andreszucs]

Yes, got some homework to do!
If my intention if to make a reliable product, I would actually need to consider the forces of the strongest athletes in the world...not me. lol

I'll also need to consider the material properties that I will be using to print this. Yield (mpa) I guess will be the primary spec to use? Just don't know how to enter that on SW...yet!


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[whilgenberg]

What materials are you thinking of getting it printed in?

Depending on what you are trying to do, FEA will get you a ways but it is so dependent on boundary conditions and your mesh that it is much easier to get wrong than it is to get correct. But give it a shot anyway, at the very least you'll get some pretty pictures. . .

As to what the loading case is, take a look at what the loads are for the CEN test case for crank fatigue. I can't remember them off the top of my head but they are pretty high. They should have a factor of safety built into them as well unless otherwise stated. Make sure that you do have some sort of factor of safety.

Lastly, if you are thinking of having such a simple profile for the tooth, might it not be easier to machine it? If easier, then it would also likely be cheaper and have the potential for better material properties too depending on what you want to use. I know laser sintering can be kind of limiting as far as the materials that can be used.

[andreszucs]

What materials are you thinking of getting it printed in?

Depending on what you are trying to do, FEA will get you a ways but it is so dependent on boundary conditions and your mesh that it is much easier to get wrong than it is to get correct. But give it a shot anyway, at the very least you'll get some pretty pictures. . .

As to what the loading case is, take a look at what the loads are for the CEN test case for crank fatigue. I can't remember them off the top of my head but they are pretty high. They should have a factor of safety built into them as well unless otherwise stated. Make sure that you do have some sort of factor of safety.

Lastly, if you are thinking of having such a simple profile for the tooth, might it not be easier to machine it? If easier, then it would also likely be cheaper and have the potential for better material properties too depending on what you want to use. I know laser sintering can be kind of limiting as far as the materials that can be used.

I guess I'm putting my efforts towards this side project to prove my point....or at least to answer my questions about the limits and possibilities of 3d printing. The only way this will work is if I manage to create a product that is competitive in price and weight with existing stuff in the market. The only material that can make this happen is stainless steel...not the ideal material but is the most affordable, yet to be confirmed if I can drop the weight down to our happiness lol.

I've already printed some small parts in stainless and I was impressed by the details so I'm confident that would work fine...not perfect but fine for cogs and chain rings. Regarding the laser sintering process and If I understand it right, after the particles are fused together, would create a very solid and uniform part correct? do you believe the mesh would still be a problem?

I'm not interested in machining it because is not part of my goal. I want to stick with 3d printing and potentially prove that can be a good alternative to the general population, freedom of expression...Industrial revolution!

CEN test...can I find that on google?

[andreszucs]

New addition: Ashima Worlds Lightest Ai2 140mm rotor for the rear...yes, they exist!
62g on my scale


New weight: 18.98lbs without pump and repair kit.

[andreszucs]

Shouldnt be too hard.
Look at your max power output and at which RPM this was. Then calculate the force on the pedal. Torque is this force times the crank arm length.
The force on the chainring tips would then be this torque multiplied with the outer diameter of the chainring (at the chain).

Something like this could give you a basic idea of the forces that are in play. Basic structural design should give you an idea of what thickness you need for chainring structure.

All right, I'll use your feedback to ask everyone these numbers.

If anyone knows...please post! I can perhaps start putting together a list with average numbers and apply this later to my models.

Thanks!

[BmanX]

great build

[andreszucs]

I thought I'd post here the culmination of my work Cad modeling a chainring...here is a successfully functioning 3d printed chainring after a test ride:



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[MattBeOne]

Looks awesome!
Smart how you applied 3D printing to step away from just a flat chainring and use out of plane stiffness as well!
How many miles are on there all ready?

[andreszucs]

Looks awesome!
Smart how you applied 3D printing to step away from just a flat chainring and use out of plane stiffness as well!
How many miles are on there all ready?

Lots of fun designing this. Very cool to be able to imagine things and translate that to the real world. The extruded structure is quite of an interesting concept, it does add lateral stiffness but its doesn't interfere on the overall yield strength on the part. Looks cool as well.

Its a whole different story after running all the simulations...it gave me confidence that it would work...an it did as predicted! Also nice to know (in theory) how strong it is. I don't have all the equipment to run real world tests...so I only have the computer regenerated data to back me up.

But anyways...it was a fun project, opening doors for a whole new chunk of ideas here...

Very little miles on it....just about 2 short rides....but going uphills riding as hard as I could! But I am not worried that is going to break, it won't (again...in theory)! Regarding durability....I thinking its going to last for a long time since is stainless steel...even if is 3d printed stainless, its certainly harder than Alloy rings commonly seeing on the market today.

[CulBaire]

Looks cool!

[CGT]

Wow, truly amazing!

[CamW]

That chainring is awesome! But key question here.... how much does it weigh?

[andreszucs]

That chainring is awesome! But key question here.... how much does it weigh?

Still a secret

[andreszucs]

Quite interesting to compare these gear ratio...and no, I didn't put this chart on my own (I'm not on that level of Nerdiness)...you can do it yourself with your bikes - http://sheldonbrown.com/gears/

This one is sorted as: Miles/hour at 90RPM (the result in black is the resulting speed riding at 90RPM for that gear).
First column - cassette config
Second and Third Column: Crank config



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