Custom chainrings

[fpavao]

Anyone made them?

As I gather, you just adjust the pitch and bcd measures on a cad program, have them cut and then taper the tip of the theeth. Couldn't find anything regarding best taper angle and stuff like this, though.

Also, what material would be better? I'm thinking 7005 aluminum and maybe anodyzing it later for better finish.

I'm trying to make one for singlespeed/internal gears, so I don't have to worry about ramps and pins or shifting yet.

[Mike Mcdermid]

https://instagram.com/p/rz6ENJvEZX/

https://instagram.com/p/tbAGKGvEV9/

https://instagram.com/p/r7PKNUvEbD/

https://instagram.com/p/tbAGKGvEV9/

https://www.flickr.com/photos/compos...posted-public/

15068412841_6b02bc617c_k.jpg

14905697328_356639770c_k.jpg

[andrew]

Really Mike, is there anything that you haven't already done? And done very well? Happen to have a 40 in a 130bcd? Been thinking about a narrow/wide for the cross bike this season.
Andrew

[fpavao]

Those are beautiful, Mike. Is it all CNC machined?

I'm thinking about using water jet cutter, It will be a lot cheaper I believe, but without the 3d feel.

Do you have any info on the teeth taper?

[Allan Varcoe]

Waterjet would be cheaper but the chainring would be thinner as waterjet is, for the most part, kind of a 2D process. I say send it to some local shops and see what they'd charge. In Los Angeles most shops charge around $80-85/hr. For a 1 off part I'd expect to pay 2-3 hrs in labor plus materials and anodizing. You're going to have to really want a 1 off chainring.

[ParagonMachineWorks]

Waterjet would be cheaper but the chainring would be thinner as waterjet is, for the most part, kind of a 2D process. I say send it to some local shops and see what they'd charge. In Los Angeles most shops charge around $80-85/hr. For a 1 off part I'd expect to pay 2-3 hrs in labor plus materials and anodizing. You're going to have to really want a 1 off chainring.

Sadly it will cost you more than that. Add in programming, tooling and setup time and you'll easily be looking at a couple hundred bucks. Want 2? $400. Want 10? $414? Want 100? $500...you get the idea. It's a common misconception in the manufacturing industry that the more parts you make the cheaper it will be. This only really kicks in after your initial run of parts. With custom parts, it's not the machine time that the manufacture is charging you for, it's the machine downtime that occurs as you set it up and get everything dialed in. There is a lot of work that goes on between receiving a dimensioned/toleranced drawing and actually seeing a finished part.

[fpavao]

Actually, the one off chainring would be a very simple 2d design mostly for prototyping and for a cost estimate. Then, maybe if everything goes right, I'd try to sell them on a more standarized version.

There is a small supply on the market of chainrings here (Brazil), and as fixed gear is still a fad, people look for 'exotic' sizes, like 47 or 49 teeth. Also, local manufacturing is always better than the chinese crap most distributors sell.

[Mike Mcdermid]

Those are beautiful, Mike. Is it all CNC machined?

I'm thinking about using water jet cutter, It will be a lot cheaper I believe, but without the 3d feel.

Do you have any info on the teeth taper?

Tech Docs | bicycle manufacturing limited

you can download the basic tooth geometry here, if your using solidworks it is native

I have not uploaded the cad model shown in the photos we have a lot of time tied up in that tooth geometry to stop it dropping chains
they work we have had no failures and the ceramic coating i hear is still going strong

[Rody]

Thanks for sharing your work Mike, very selfless.

rody

[Allan Varcoe]

Add in programming

As a programmer myself I can't believe I forgot to add programming time! HAHA!

Heres a BMX sprocket I made when I was an apprentice. I made two and had the one I used anodized. I was (and still am) so proud to have made something like this for myself.
Sprocket.jpg