# CNC Mill for a Mountain Bike Component



## texas-two-step (Mar 6, 2017)

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!


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## TomS (Mar 6, 2017)

texas-two-step said:


> 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.


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## texas-two-step (Mar 6, 2017)

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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## woodchucker (Mar 6, 2017)

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


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## coherent (Mar 6, 2017)

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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## texas-two-step (Mar 6, 2017)

woochucker said:


> 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!


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## texas-two-step (Mar 6, 2017)

coherent said:


> 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!


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## ddickey (Mar 6, 2017)

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.


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## ddickey (Mar 6, 2017)

Oops. I was writing my response before I saw yours.


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## TomS (Mar 6, 2017)

texas-two-step said:


> 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.
> 
> ...



When you get the drawing done let me know.

Tlom S.


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## rwm (Mar 6, 2017)

If that part is cast it is not likely to be 6061 which is not a casting alloy. If I was machined from billet it may be 6061. Can you tell how it was produced?
How much does that part cost now?
Robert


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## ddickey (Mar 6, 2017)

The quality ones are billet.


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## adamgoldberg (Mar 6, 2017)

I assume, but have to ask, you've checked with Wheels Mfg?


Sent from my iPhone using Tapatalk


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## texas-two-step (Mar 12, 2017)

Looks to be billet as ddickey pointed out with pics of an NSB mfg hanger. 

The Mfg wants $50 for the part. Most hangers go for about $20. Even the local bike shop, who is a dealer for the Mfg, had a tough time getting the right part FROM THE MFG. It's disheartening.



rwm said:


> If that part is cast it is not likely to be 6061 which is not a casting alloy. If I was machined from billet it may be 6061. Can you tell how it was produced?
> How much does that part cost now?
> Robert


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## texas-two-step (Mar 12, 2017)

Yes Adam, I've scoured all sources. It must be there are so few of these bikes in the wild that there's not much opportunity to make it worth their effort.

BTW, used to live in Ashburn. Know your area well, but for all the changes in 16 years since leaving.  



adamgoldberg said:


> I assume, but have to ask, you've checked with Wheels Mfg?
> 
> 
> Sent from my iPhone using Tapatalk


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## texas-two-step (Mar 12, 2017)

dh stl file on dropbox

Can't upload to here - the .stl isn't in the allowed list of extensions. 



TomS said:


> When you get the drawing done let me know.
> 
> Tlom S.


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## TomS (Mar 13, 2017)

texas-two-step said:


> dh stl file on dropbox
> 
> Can't upload to here - the .stl isn't in the allowed list of extensions.



I downloaded the file into CamBam.  I'll also try opening it in Fusion 360.  In either case I'll need to create the CAM files and run simulation.  I'll report back.

Tom S.


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## texas-two-step (Mar 13, 2017)

It was created in Inventor Fusion (same product family as Fusion 360). I have an extension of .f3d for the native file if the .stl doesn't work.

Thank you!


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## DSaul (Mar 13, 2017)

Wheels manufacturing #237 certainly looks like the part.  http://wheelsmfg.com/derailleur-hangers/derailleur-hanger-237.html


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## texas-two-step (Mar 13, 2017)

DSaul said:


> Wheels manufacturing #237 certainly looks like the part.  http://wheelsmfg.com/derailleur-hangers/derailleur-hanger-237.html



Holy cow, it certainly is! I searched that site and NSB top to bottom. How is it they want $50 for it when everything else goes for $20 I wonder?


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## TomS (Mar 13, 2017)

texas-two-step said:


> It was created in Inventor Fusion (same product family as Fusion 360). I have an extension of .f3d for the native file if the .stl doesn't work.
> 
> Thank you!



With a work around I was able to open it in Fusion 360.  Is this drawn to scale?  When I open and measure it it is huge.

Tom S.


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## texas-two-step (Mar 13, 2017)

TomS said:


> With a work around I was able to open it in Fusion 360.  Is this drawn to scale?  When I open and measure it it is huge.
> 
> Tom S.



Something isn't correct then ... modeled in millimeters. 55mm long, 21.75mm at the widest point.

Try the native file:  https://www.dropbox.com/s/y1qbzksind6x0yb/derailluer hanger v2 copy.f3d?dl=0  Fusion should be able to handle this natively.


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## TomS (Mar 14, 2017)

texas-two-step said:


> Something isn't correct then ... modeled in millimeters. 55mm long, 21.75mm at the widest point.
> 
> Try the native file:  https://www.dropbox.com/s/y1qbzksind6x0yb/derailluer hanger v2 copy.f3d?dl=0  Fusion should be able to handle this natively.



The other file opened as a part 550mm wide by 1350mm long.  No matter as the f3d file works.  Like I said in my first post I'm on an extended vacation but in my spare time I'll play around with the CAM side of things.  I'm by no means a Fusion 360 expert so it may take a few iterations to get it right.

Tom S.


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## texas-two-step (Mar 14, 2017)

TomS said:


> With a work around I was able to open it in Fusion 360.  Is this drawn to scale?  When I open and measure it it is huge.
> 
> Tom S.



I'd say that  would be one huge derailleur!

I've ordered a 3D plastic part to test the fitness of the model in hopes of avoiding wasted machine time. Should be here early next week. Good to know it IS a native Fusion file. 

I checked out a few of the Cambam videos just to get a better idea of what that's all about. I've done 2D paths on a laser table for creating balsa parts and that was a real challenge having to create the tool paths while creating the drawing. Now I remember why I only did one project.


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## TomS (Mar 15, 2017)

texas-two-step said:


> I'd say that  would be one huge derailleur!
> 
> I've ordered a 3D plastic part to test the fitness of the model in hopes of avoiding wasted machine time. Should be here early next week. Good to know it IS a native Fusion file.
> 
> I checked out a few of the Cambam videos just to get a better idea of what that's all about. I've done 2D paths on a laser table for creating balsa parts and that was a real challenge having to create the tool paths while creating the drawing. Now I remember why I only did one project.



I like CamBam a lot but the challenge is getting Fusion and CamBam to cooperate with each other.  There isn't one file format that works with both programs so I'm having to learn the intracasies of Fusion CAM.  The curved transition surface will be particularly interesting because it is 3D.  I'll get there.

Tom S.


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## TomS (Mar 18, 2017)

Just a brief update on where I'm at with the CAM side of things.  As I mentioned in an earlier post I'm on vacation and can only work on this occasionally.  I do have the CAM done but I need to spend some time fine tuning it.  Starting out I knew just enough about Fusion 360 CAM to make simple 2D and 2.5D parts so this part forced me to dig deeper into how Fusion works.  I'm getting it, slowly.  Hope to have something to post soon.

Tom S.


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## texas-two-step (Mar 18, 2017)

Always fun learning new things. Let me know if I can assist in any way. Thanks Tom!


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## TomS (Mar 18, 2017)

texas-two-step said:


> Always fun learning new things. Let me know if I can assist in any way. Thanks Tom!



I'm anxious to post the file so I can get feedback from you and others but I want to correct known errors before doing so.

Tom S.


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## British Steel (Mar 19, 2017)

Were you closer I'd run the STL file into Rapid Prototyping and  have 'em print one in carbon-fibre loaded ABS...

Dave H. (the other one)


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## TomS (Mar 19, 2017)

TomS said:


> I'm anxious to post the file so I can get feedback from you and others but I want to correct known errors before doing so.
> 
> Tom S.



I'm fine tuning the CAM but have a few questions.  Your drawing specifies two very small radius' one being 1mm and the other .5mm.  There are other sections of your drawing where radial cuts meet flat surfaces and no radius is specified.  Looking at the part from WheelsManufacturing.com their part has radius' at all transitions.  What is the maximum radius you can live with at each of these transition points?  Can I assume the .093" hole is tapped M3x8?  Can it be a through hole? 

Tom S.


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## texas-two-step (Mar 20, 2017)

TomS said:


> I'm fine tuning the CAM but have a few questions.  Your drawing specifies two very small radius' one being 1mm and the other .5mm.  There are other sections of your drawing where radial cuts meet flat surfaces and no radius is specified.  Looking at the part from WheelsManufacturing.com their part has radius' at all transitions.  What is the maximum radius you can live with at each of these transition points?  Can I assume the .093" hole is tapped M3x8?  Can it be a through hole?
> 
> Tom S.



The .5mm is likely an errant artifact left behind from my tinkering to get the model generated. The hole will be tapped as an M3x8 - cut through is fine if that's easier! I just blew out a WheelsMan (the replacement hanger) on Thursday. The unit they produce now is x8 depth and doesn't go through completely.

I think I blew it and removed some of the sketches that had the radius markings listed. I'm not sure how to best answer the question about the max radius ... perhaps what the tooling allows? 

I have an acquaintance that did a quick draft from the file I created in order to help me learn more about modeling - he accomplished it in 8 steps. There is one image showing the diameter of the hanger as 27.5mm (radius of 13.75) at the transition. I'll check to see what the radius is on the axle portion - I'm sure he kept the file.


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## texas-two-step (Mar 20, 2017)

Printed part came in today. 

It's really, really close but a few dimensions are just slightly larger. Not sure yet as to why yet, will invest some time checking against the actual parts. It might have had to do with the conversion of the file to .stl - similar to what you experienced, just on a smaller scale. 

Busy next two days with biz projects. Should have time Wed night to get into the details.


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## TomS (Mar 21, 2017)

Here's a Drop Box link to the Fusion 360 file.  A couple of notes.  The CAM processes are not necessarily in order.  I'm still learning Fusion CAM and working on refining it.  All of the milling CAM is done with a 1/4" end mill.  If the inside corner radius is too big I can look at a smaller end mill.  I haven't looked at what size and flute lengths are available.  The holes are drilled not bored or reamed.  If a precision hole placement and size are required I can adjust the CAM to suit.  My initial plan is to machine the Z height to final dimension, rough out the profile, and machine the bottom features including the three holes.  Then use a fixture to locate the part using one of the two large holes and the small hole to machine the top features.  Any comments, suggestions and criticism are welcome.

https://www.dropbox.com/s/kocw9eif7z183pk/Deraileur v11.f3d?dl=0

Tom S.


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## texas-two-step (Mar 24, 2017)

TomS said:


> Here's a Drop Box link to the Fusion 360 file.  A couple of notes.  The CAM processes are not necessarily in order.  I'm still learning Fusion CAM and working on refining it.  All of the milling CAM is done with a 1/4" end mill.  If the inside corner radius is too big I can look at a smaller end mill.  I haven't looked at what size and flute lengths are available.  The holes are drilled not bored or reamed.  If a precision hole placement and size are required I can adjust the CAM to suit.  My initial plan is to machine the Z height to final dimension, rough out the profile, and machine the bottom features including the three holes.  Then use a fixture to locate the part using one of the two large holes and the small hole to machine the top features.  Any comments, suggestions and criticism are welcome.
> 
> https://www.dropbox.com/s/kocw9eif7z183pk/Deraileur v11.f3d?dl=0
> 
> Tom S.



I've managed to get access to Fusion 360. The model I generated in Inventor is certainly flawed to a degree and I suspect the issues you're experiencing in the CAM process are likely resulting from those errors. I'm working on creating a new model from the ground up but taking a more methodical approach and investing time in learning Fusion. It's significantly more flexible and feature rich than the Inventor product. I expect much better results.

Looking to having it ready by Sunday for review.

Thanks!


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## TomS (Mar 24, 2017)

texas-two-step said:


> I've managed to get access to Fusion 360. The model I generated in Inventor is certainly flawed to a degree and I suspect the issues you're experiencing in the CAM process are likely resulting from those errors. I'm working on creating a new model from the ground up but taking a more methodical approach and investing time in learning Fusion. It's significantly more flexible and feature rich than the Inventor product. I expect much better results.
> 
> Looking to having it ready by Sunday for review.
> 
> Thanks!



Sounds good.  The model you sent is workable but I did have some problems with the CAM but that could just be me.  No reflection on what you put together.  I'm still refining the CAM processes to get a more fluid machining cycle.  I've got a couple of ideas of how to get a smaller radius on the "fishtail" end. 

Tom S.


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## texas-two-step (Mar 24, 2017)

TomS said:


> Sounds good.  The model you sent is workable but I did have some problems with the CAM but that could just be me.  No reflection on what you put together.  I'm still refining the CAM processes to get a more fluid machining cycle.  I've got a couple of ideas of how to get a smaller radius on the "fishtail" end.
> 
> Tom S.



The 'fishtail' is one of those features I deleted. It's a revolute operation on the x axis. Almost finished with the newest rev of the drawing.


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## texas-two-step (Mar 25, 2017)

V3 now available.
https://www.dropbox.com/s/hm6vqv0akzicygg/Derailleur Hanger v3.f3d?dl=0


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## TomS (Mar 25, 2017)

texas-two-step said:


> V3 now available.
> https://www.dropbox.com/s/hm6vqv0akzicygg/Derailleur Hanger v3.f3d?dl=0



Got it.  I'll start working on the CAM.

Tom S.


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## cs900 (Mar 25, 2017)

what are the chances we could put radius' here:


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## TomS (Mar 26, 2017)

cs900 said:


> what are the chances we could put radius' here:
> View attachment 229718



Same questions I had.  See post #30.  Also take a look at post #19.  The link is to a vendor of this part.  The pictures show radius' at the points indicated in your drawing.  I'm setting up the CAM processes using a 1/4" end mill then will use something smaller for finishing the "fishtail" inside radius.  Haven't come up with a size yet.  Still working my way through learning Fusion CAM.

Tom S.


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## texas-two-step (Mar 26, 2017)

cs900 said:


> what are the chances we could put radius' here:
> View attachment 229718



It's no problem to add a fillet here, just an oversight on my part. Fillets are 2mm in size. Let me know if that's enough or if the cutting tool is larger and needs more radius in the fillet. Took advantage of this oversight and fixed up the revolute on the hanger face and cleaned up the appearance.

https://www.dropbox.com/s/o8zr90yxbeun1ad/Derailleur Hanger v4.f3d?dl=0

Let me know what you think! Thanks!


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## cs900 (Mar 27, 2017)

how large of a fillet can you put there? The larger, the easier it is to make. If you could get away with something like R.13-.15 that would be perfect for a .25 dia tool. If it hasto be smaller that's fine, it just increases machining time.


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## TomS (Mar 30, 2017)

I haven't forgotten this project.  I'm traveling in the southwest and wifi is intermittent at best.  

Tom S.


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