If you can't find it... custom chainring

Vintage, yesteryear and retro biking

If you can't find it... custom chainring

Postby Clydesdale Scot » Sat Jan 26, 2013 3:20 pm

I was wanting a chainring like this for a Malvern Star project I am slowly working on.
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as I have set out in the MS 'Coronation' thread
I drew it up in Illustrator by tracing a high resolution image kindly sent by cycles gitane, the key measurement is the PCD of 50.4 for the cranks. The teeth are taken from a free online creator using standard bike chain measurements of pitch and roller size, with my preference for 44 teeth. The file generated is exported as a DXF file, then converted with an online DXF to PDF converter, then the PDF was taken into Illustrator and resized to fit the size required. The Illustrator file can then be exported out as a DXF file which can be used as the input to generate the G code required in the laser cutting/engraving. Surprisingly, the laser cutting company was happy with the drawing and all I need to do now is to send the file so they can do the quote.

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My dxf file was then prepared by the laser cutting company
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and it was laser cut and lightly engraved using 3mm stainless steel.
Image
the path with the little ovals was lost but I think I know how to overcome that if I have anything else engraved.
The five mounting holes fit the crank arm position and need to be enlarged and sleeved, and threads tapped like the Williams chainrings, another project for a mate.
Running it along a 1/8" chain sees the teeth mesh smoothly.

very happy with the price and the result.
Philip
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by BNA » Sat Jan 26, 2013 3:26 pm

BNA
 

Re: If you can't find it... custom chainring

Postby HappyHumber » Sat Jan 26, 2013 3:26 pm

Nice... thanks for sharing.
Wouldn't be for a Coronation Special would it? :)
- Kym
Please don't assume I'm on Facebook.
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Re: If you can't find it... custom chainring

Postby GaryF » Sat Jan 26, 2013 4:30 pm

Great job.
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Re: If you can't find it... custom chainring

Postby amrjon » Sat Jan 26, 2013 6:17 pm

That's some serious DIY, well done.
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Re: If you can't find it... custom chainring

Postby silverlight » Sat Jan 26, 2013 8:10 pm

Very very Awesome Philip
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Re: If you can't find it... custom chainring

Postby Ph billet » Sun Jan 27, 2013 9:12 am

Great job,never seen a chain ring like that.
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Re: If you can't find it... custom chainring

Postby boyracer » Sun Jan 27, 2013 10:40 am

Nice work Phillip.
Deja vu....I was asked who would be good to speak to regards very custom chainrings just this week. I thought of you and your honking rubbers. I was just about to ask you about this scenario for said mate in Melbourne.

Mind if he Pm's you for more details?
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Re: If you can't find it... custom chainring

Postby Clydesdale Scot » Sun Jan 27, 2013 3:39 pm

thanks for the comments.
I am about to try to make some chainguard fittings inspired by Amrjon's excellent work

the chainring and the chainguard are both for the MS 'Coronation' for my wife, Liz. An appropriate bike for her!

Boyracer, please have you mate PM me, happy to help.

Philip
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