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

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

Postby Clydesdale Scot » Sat Jan 26, 2013 4:20 pm

I was wanting a chainring like this for a Malvern Star project I am slowly working on.
Image
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.
Image
My dxf file was then prepared by the laser cutting company
Image
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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HappyHumber
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Re: If you can't find it... custom chainring

Postby HappyHumber » Sat Jan 26, 2013 4:26 pm

Nice... thanks for sharing.
Wouldn't be for a Coronation Special would it? :)
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GaryF
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Re: If you can't find it... custom chainring

Postby GaryF » Sat Jan 26, 2013 5:30 pm

Great job.

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

Postby Ferrovelo » Sat Jan 26, 2013 7:17 pm

That's some serious DIY, well done.

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

Postby silverlight » Sat Jan 26, 2013 9:10 pm

Very very Awesome Philip

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Ph billet
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Location: Sydney

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

Postby Ph billet » Sun Jan 27, 2013 10:12 am

Great job,never seen a chain ring like that.

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

Postby boyracer » Sun Jan 27, 2013 11:40 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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Clydesdale Scot
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Re: If you can't find it... custom chainring

Postby Clydesdale Scot » Sun Jan 27, 2013 4:39 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

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

Postby Retro » Sun Aug 04, 2019 1:59 pm

Hi Clydesdale Scot,

I posted some years ago to try to locate a chain ring for my bike, with out success. I have just stumbled on your post, (which I missed at the time), about having one made. I know it is some years since your post on your custom Malvern Star "Coronation" chain ring, but would you still have the drawings you sent to have one made that you would be kind enough to share? I have no idea how to draw up something to have one made.
My bike is an Elizabethan, and I would have preferred the plainer ring, but I just want to get it going. I inherited my bike from my mother when I was 7 & rode it for many years before by sons stole my chain ring and attached parts, when it was stored, to use on their BMX bike, (which I did not realise till too late). I have never had a more comfortable bike to ride, so want to buy, or have made, a ring with the same diameter and number of teeth. (Along with pedals etc)
If you, or anyone else out there can help, I would greatly appreciate it.
Thanks, Sandra (aka Retro)

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Clydesdale Scot
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Location: Adelaide, SA

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

Postby Clydesdale Scot » Sun Aug 04, 2019 4:22 pm

I am a bit unsure as to the 'plainer ring' you mention.
If you want one of the same design as the one I drew, then I would recommend you contact the firm set out on the drawing image to see if they still have that file in their system. You would need to get the holes tapped out as I mentioned.
However, none of the Malvern Star series of this shape had the crown chainring. I did that as a folly.

The standard Williams set would be ideal. Unless you wanted to go very much over the top as I did.
Which city do you live? There may be suggestions as to where to get an appropriate set.

Any photos of your bike?

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

Postby uart » Sun Aug 04, 2019 8:26 pm

Clydesdale Scot wrote: Running it along a 1/8" chain sees the teeth mesh smoothly.

very happy with the price and the result.
Philip
Thanks for sharing Philip, very cool. :)


Old thread I know, but seeing as it's been bumped I'll ask a question. Just wondering if you ever put any chamfer (or profile) on the teeth, or was it all just left a uniform thickness throughout?

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Clydesdale Scot
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Location: Adelaide, SA

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

Postby Clydesdale Scot » Sun Aug 04, 2019 8:35 pm

When I fitted it the chain didn't always engage with the chainring teeth. So I hand filed a little of the leading edge and that worked.
It was an interesting exercise and I was surprised at how well it turned out.

Still contemplating on how I will do the Lytaloy cranks.

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