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GTaholic
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Discussion Starter · #1 ·
Hello everyone.

I just bought 3.75mm carbon fiber sheet, 2mm aluminum sheet and I should get 3mm titanium sheet soon.

I have drawn these in SolidWorks 2008.

I just cut out everything in 3 mm steel and looking if there´s some errors, it was none.

I cut out the inner ring in Carbon-Al but it doesn´t turn out good because of delaminating when I use a Abrasive Water jet machine, any tips, I have no CNC mill here.

Metals is no problem but Carbon and similar composites will delaminate..

But keep this thread alive so I can post my progress.
I just drawn a own Ti cassette and will try it in steel first and see if it´s doable with a good weight saving.
 

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GTaholic
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760 Posts
Discussion Starter · #2 ·
I will only comment, the first chainring in 3mm Domex is on my road/commuter bike with compact 94mm bolt circle, does work OK.
No fancy shiting ramps and like here.
 

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SUBLIM8er
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I will be following this thread. Very impressed with the drawings so far. Allow me to offer my services as a "test pilot." ;)
 

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You should be running all these designs in CosmosXpress and getting some FEA results on deflection. It looks like some of your designs are more cosmetic than functional, especially the first chainring, which has no bridges to transfer the load between the mounts.

Also, that 'bashguard' would be hell to machine, and would not stand up well in fatigue. Remember, you want to avoid making extra holes in a part, especially if they are not circular or radiused. Why don't you go for something a bit simpler, you don't need all that complexity.
 

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GTaholic
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Discussion Starter · #6 ·
Ginsu2K, yes my design is only for my pure free time and because it´s fun to make these drawings.
That´s NOT a bashgurd that´s pictured there, it´s a new inner section of Carbon-Al chainrings because of delaminationg in the carbon composite when cutting in a AWJ.

I will try them on my trainer and first sitting and powering on, then more upright and in a more controlled envronment than on the road with other cars.
 

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GTaholic
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Discussion Starter · #7 ·
Machine time is no problem when I run a water jet machine, all curves is the same not less than 1mm between lines because the beam is 1mm and at 4000 bar, it will cut anything, even titanium and tungsten.
 

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I think that inner section should be alu, not titanium. titanium just for teeth (more wear resistant)

where did you buy the carbon fiber sheet?
 

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GTaholic
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Discussion Starter · #10 ·
STS, you may have a point here.

I will try a little more combinations before I make a final production run for my own use.

Never abandon 5 bolt compact chainrings!
 

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Over on the Fair Wheel bike forum the owner of Fyber Lyte(think his name is Stephan) hangs out and post a good bit. I think he would be the most likely to have advise for you on the delamination topic. I'de throw it out to those guys, and Madcow is pretty smart too. Really nice stuff your working on, I'll be watching with interest.
 

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What type of waterjet are you running? I would think that a waterjet would be able to cut carbon without delamination. I used to own a business and we made cosmetic parts for cars such as interior trim kits. We used a waterjet exclusively. Most products were aluminum, but we had a few carbon parts. But maybe the reason we had no delamination was because the carbon material we used was for looks only and very thin. Since our parts were rather delicate, we would turn down the speed, run a much finer abrasive, and increase the pressure.

If the carbon is delaminating under a waterjet, it might delaminate with a CNC as well.

Mattias_Hellöre said:
Ginsu2K, yes my design is only for my pure free time and because it´s fun to make these drawings.
That´s NOT a bashgurd that´s pictured there, it´s a new inner section of Carbon-Al chainrings because of delaminationg in the carbon composite when cutting in a AWJ.

I will try them on my trainer and first sitting and powering on, then more upright and in a more controlled envronment than on the road with other cars.
 

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Team Captain
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If you're interested in cutting carbon with a waterjet, a secret trick is to sandwich it in between layers of aluminum and bolt that whole shebang together before running it.
 

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GTaholic
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Discussion Starter · #15 ·
Very good tips folks!
I will give it some tries before I decide to use a company like Fibre-Lyte to make my prototypes.

Sandwiching is the way to make this carbon stuff I think.
 

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It would seem to me that "water jet" is the wrong tool for cutting carbon fiber sheet when metal cutting tools do it so easily?

Good luck though :thumbsup:
 

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GTaholic
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Discussion Starter · #17 ·
Slobberdoggy, I wish I could choose a CNC mill but there´s no one on my job only a €130.000 abrasive water jet machine which I are familiar with.

I talked little with Fibre-Lyte and he said a mill or alathe is the best way to make these things.

I will give it some tries before I change my mind.
 

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GTaholic
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Discussion Starter · #18 ·
Hi everyone, here is my Carbon-Al chainring in 44T.

The weight is below 50 gr for this chainring but durability is a good question I will find out soon.

I can do the toothed outer ring in Ti and getting a cool chainring that WILL last.

I will do a similar in 30 or 29T config and see how far I can push this design.

Enjoy!
 

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