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

Posted: Sat Jan 26, 2013 4:20 pm
by Clydesdale Scot
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.
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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

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

Posted: Sat Jan 26, 2013 4:26 pm
by HappyHumber
Nice... thanks for sharing.
Wouldn't be for a Coronation Special would it? :)

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

Posted: Sat Jan 26, 2013 5:30 pm
by GaryF
Great job.

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

Posted: Sat Jan 26, 2013 7:17 pm
by Ferrovelo
That's some serious DIY, well done.

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

Posted: Sat Jan 26, 2013 9:10 pm
by silverlight
Very very Awesome Philip

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

Posted: Sun Jan 27, 2013 10:12 am
by Ph billet
Great job,never seen a chain ring like that.

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

Posted: Sun Jan 27, 2013 11:40 am
by boyracer
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?

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

Posted: Sun Jan 27, 2013 4:39 pm
by Clydesdale Scot
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