CNC Mill for a Mountain Bike Component

texas-two-step

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I'm looking for a Hobby CNCer here in Texas to help with a very small part that was only available for two model years on two different bikes from a single manufacturer. With each passing year, the part (a derailleur hanger) is getting more difficult to obtain. In a few more years, and it won't be available at all. The unfortunate aspect is this part is subject to failure in the course of regular use (and the bike gets used hard!)

This forum category seems like a good starting point. Any suggestions where else to look are certainly welcome.

Thanks!
 
I'm looking for a Hobby CNCer here in Texas to help with a very small part that was only available for two model years on two different bikes from a single manufacturer. With each passing year, the part (a derailleur hanger) is getting more difficult to obtain. In a few more years, and it won't be available at all. The unfortunate aspect is this part is subject to failure in the course of regular use (and the bike gets used hard!)

This forum category seems like a good starting point. Any suggestions where else to look are certainly welcome.

Thanks!

How soon do you want it? I'm heading out on vacation tomorrow and will be back mid-April. Although I'm not in Texas I'd be glad to take a look. Can you post a picture or a drawing?

Tom S.
 
Hello Tom,

I'm not in a rush (yet!) and will be working on creating a 3D CAD file of the part. Not a huge issue being out of Texas - was hoping to find someone close in order to learn more about CNC setups and working with materials for my own edification.

Here are pics of the failed part with a Quarter for reference. The larger end is 12mm that holds the axle in place, the smaller is standard (though I don't know the dimensions yet) mount for the derailleur itself. A small M8x3 fastener holds the part in place on the frame.

Thanks for the response.



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Question, are you hitting that part on rocks, or falling on it. Or is it just stress causing it to crack?
I don't have the ability to help, but I am curious about where the source of the fatigue is coming from. It could require a better metal. What is it made out of now? Cast Aluminum? Cast metal (pot metal). How much would you be willing to spend, I think titanium might make it impervious to future damage and shock. Or possibly 6061 if it is cast Aluminum
 
It looks like aluminum and shouldn't be difficult. There may even be a way to increase it strength so avoid the breakage depending on how it mounts/fitment.
While there is still a supplier available, see if you can track down the supplier and/or even better the manufacturer. Tell them your concern and ask them for the cad drawings of the part in case it becomes unavailable in the future. They may be willing to provide them to you. Many part and fastener suppliers post such data on their web sites.

It would make it much easier for someone to cut one for you if they (or you for that matter) didn't have to take the time to produce the cad drawings themselves. It can take longer to do so than actually cut/fabricate the part depending on it's complexity. If nothing else a pdf or drawing of the dimensions is better than nothing.
 
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Question, are you hitting that part on rocks, or falling on it. Or is it just stress causing it to crack?
I don't have the ability to help, but I am curious about where the source of the fatigue is coming from. It could require a better metal. What is it made out of now? Cast Aluminum? Cast metal (pot metal). How much would you be willing to spend, I think titanium might make it impervious to future damage and shock. Or possibly 6061 if it is cast Aluminum

Trail hazards come in many forms! In this case, the chain jumped the top sprocket and wedged between the spokes and cassette a few times - I really should have stopped and adjusted the low end limit, but was having too much fun up until that point. It weakened the joint to the point that when under heavy load (my weight, plus a gnarly hill climb) and it failed.

The part is designed to fail to protect the much more expensive derailleur. So, as much as I like the idea of Ti hanger, it would defeat it purpose.

From the break, it appears to be cast Aluminum. I suspect a part made of T-6061 would be much stronger and more flexible - hangers do get bent out of shape and need tuning from time to time- but I'm no materials expert, just making a presumption.

Thanks for your input!
 
It looks like aluminum and shouldn't be difficult. There may even be a way to increase it strength so avoid the breakage depending on how it mounts/fitment.
While there is still a supplier available, see if you can track down the supplier and/or even better the manufacturer. Tell them your concern and ask them for the cad drawings of the part in case it becomes unavailable in the future. They may be willing to provide them to you. Many part and fastener suppliers post such data on their web sites.

It would make it much easier for someone to cut one for you if they (or you for that matter) didn't have to take the time to produce the cad drawings themselves. It can take longer to do so than actually cut/fabricate the part depending on it's complexity. If nothing else a pdf or drawing of the dimensions is better than nothing.

Great idea to hit them up for the CAD drawing. I'm able to create a 3D .stl file, just can't convert to a cutting file. It would save me a ton of time if they offered it up.

Thank you for your idea!
 
That looks like a derailleur hanger. They break when you drop a chain and keep pedaling or try to bring the chain back onto the chainring.
I believe they are designed to break before you break your frame.
 
Oops. I was writing my response before I saw yours.
 
Hello Tom,

I'm not in a rush (yet!) and will be working on creating a 3D CAD file of the part. Not a huge issue being out of Texas - was hoping to find someone close in order to learn more about CNC setups and working with materials for my own edification.

Here are pics of the failed part with a Quarter for reference. The larger end is 12mm that holds the axle in place, the smaller is standard (though I don't know the dimensions yet) mount for the derailleur itself. A small M8x3 fastener holds the part in place on the frame.

Thanks for the response.



View attachment 228048 View attachment 228049 View attachment 228050

When you get the drawing done let me know.

Tlom S.
 
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