MixteForMen

hi everyone. just continuing my ongoing search to find another engineer on this bike forum or someone who has experience with cnc machining bike components...or anyone who has useful knowledge on track chainring tooth profiles

here's the actual chainring (brand spanking new model-3200 suntour superbe pro njs 51ct chainring)


here's my solidworks re-make: isometric view


top


bottom


side

xkillemallx16

https://www.flickr.com/photos/37220746@N06/5832980002/

try this one

fixedgear80

Wow looks good! If you have a rapid prototyping machine (3-d plastic printer) I'd print one out and try it on your crankset! (low speed with your bike in a stand) You will be surprised how strong abs plastic is. Unfortunately my Industrial Design shop is all out of plastic till midterms! You know design is all about making something 30-40 times till its right. If the plastic one works you will know if you want to spend the dough to have it CNC'd. Also my Shop teacher is always asking why are you making this? Wouldn't it be cheaper (timewise-materials-mental stress) to just buy one? But you already have one??

dsprehe89

My question is, what is the point in doing all of this? You never really asked any questions except if there are any engineers on this forum. What is you question? "Is the design correct? Will it work?" What is you ultimate goal with this? Are you planning on trying to build one with a different material or what?

Hothead286

Why didn't you make your circles round? I could make something like this, but you'd have to order it through my boss and buy at least $200 worth of chainrings.

dsprehe89

The circle probably are round. You can't create a truly round object on a computer screen seeing as the pixels are squares set up in square patterns. Many CAD programs will make a circle look like it has straight edges if you zoom in or out to just the right spot. I've seen this issue on AutoCad many times

MixteForMen

the question is what makes a superior tooth profile? beyond a special coating as seen in the sugino zen s3 or with eai gold medal lines...what's the specific points in which tooth profiles differ between a sugino gigas and an origin8 chainring. and its beyond whether i'll be able to afford to cnc my own chainring as of now...i would like to know more about a bicycle beyond taking it apart and putting it back together. pursuit of knowledge.

MixteForMen

yeah...i think im going to go ask around my college (stanford) to see if i can get my hands on something. but i doubt they'll let an incoming soph mess with 3D printer freely. btw...i know what youre talking about. i met peter enright of phil wood & co. for a little chat a while back and he showed me around including their "in-development products" and of course, they had a 3D plastic print of every component. very very cool

dsprehe89

On which is the better tooth profile. I like to think that the engineers that are being paid thousands by Shimano, SRAM, and all the other main companies have already came across it. I would have to have software similar to Pro E to really be able to tell you and it would take me along time to use the software seeing as I've only used software for drafting and not force placement or system mechanics. Software such as Pro E and Inventor are designed to be used to design system and can actually show you stresses and force locations on parts in a system, and to be able to create the optimal tooth design you would also have to create the optimal chain to match it in both you design and in the real world. The tooth has to match the chain obviously and even then if you design a new chain you will also have to design a rear cog set to match it. The current tooth design that is being used by the main companies was also designed to be used with the current chains that are also being made. On top of all of this design and testing work that you would have to put into this, it would cost alot of money to have a chainring CNC'd, unless you know someone that has a machine that they would run for you. I like how you are wanting to try and design you own parts (I often do homemade garage shop stuff myself). However, if you decide to continue with this, it will be a major investment both physically and financially. I am still in the middle of getting my engineering degree so I am not technically and engineer yet, but I did work as an intern for a year and can tell you that design work is very, very, VERY expensive and you don't always get the result you are looking for. Your best bet is to keep playing with solidedge and keep making some designs, but just buy parts for your bike online. It will save you alot of money and headache down the road.

BTW are you an engineer or just a very enthusiast DIYer?

MixteForMen

im a undergrad at stanford double majoring in chemE and art (drawing & painting). deciding to pick up solidworks on the side for fun...thats my second drawing i've ever made so far. and honestly, thank you for the information...i had a feeling that should be using such software. my dads a design engineer and he advised me that another program under the solidworks umbrella called COSMOS should be able to perform the same calculations you mentioned. I haven't had a chance to give it a try...have you ever gotten your hands on it? any advice? i doubt i'll have the funds to follow through with this project anytime soon though...

dsprehe89

No, I haven't messed with other programs. I've only ever used solidedge 2D and AutoCad. Hated SolidEdge BTW. I got to see some of the senior engineers where I worked use Pro E and it looks pretty advance but easy enough to be self taught. My advice is just get your hands on and try any and all Cad software available and don't just learn the basics, learn their little details that make them different and powerful in their own way.