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frankenderailleur v2?

4130biker

4130biker

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May 24, 2007
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I have a question: Is it possible to weld cold forged aluminum? Here's why- I'm doing a "cheap" build for a 4" travel playbike, and have 4 shimano derailleurs in my toolbox in varying levels and conditions.
Anyway, I'll be running a SRS guide, and don't want to shell out for a sram short cage setup since I have all of these derailleurs. So I want to hack and re-weld the cage of one to make a short cage.
I know how to TIG weld, and have access to a welder. The xt long cage I want to try it on has an aluminum front plate, with a steel back plate. Has anyone tried this? It's more of an experiment than anything, but i'd hate to start hacking and find that forged aluminum isn't weldable.
Thanks in advance for any valuable input you may have. :)

PS- I was going to hack up the deore cage that I have (all steel) since I know it's weldable, but when I took it apart, the shaft that the cage rotates on is severely worn by the retaining pin and doesn't look worth the effort.
 
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4130biker

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If it is weldable, I'm pretty sure I can make it hold by doing the cut(s) at an angle to give me much more weldable length..
 
4130biker

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I know most people wouldn't/can't do it, but I enjoy trying things like this.
I'll give it a shot and report back.
 
4130biker

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haha, yeah, I started to think that when I started to weld earlier..
 
AngryMetalsmith

AngryMetalsmith

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Jun 4, 2006
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Forged metal is in a state called work hardened. This is the process of realigning the crystalline structure of the metal. When you heat it to it's annealing temperature the structure is scattered making the workpiece malleable. When you weld it it will lose it's work hardness in the area that it was welded but not necessarily for the entire piece.

As someone else said it would need to be heat treated.

Cold connecting would solve the problem of losing work hardness but makes more work for you. You could overlap the two sections and join them with at least two steel rivets. Nails with the heads cut off work well for rivets. You'll have to accommodate for the offset at the bottom pulley with spacers.

Cold connecting would also allow for a little more room for error in aligning the two plates for the pulleys. You could make sure everything lines up before setting the rivets.

As a smith, I say go for it.

As a rider I say don't waste your time if you can afford a rear derailleur.
 
4130biker

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First, I tried a "test" on an old xt cage. It worked, even though the metal appeared not to be forged, it may have been.


So I moved onto the xt long cage.. Prepped the S--- out of everything, brushed up on my welding, ready to go! Well, the cage didn't want to be welded. Forging doesn't seem like it should prevent welding, but I wonder if it's an un-weldable series of aluminum. It was night and day, pain in the ass compared to a. the other xt and b. the 6061 I'd done practice welds on.
This result is me throwing a tantrum and trying to melt the thing, I was so pissed at it.


I was frustrated, but I realized that the steel deore cage wasn't in as bad shape as I thought. So I went for it, because I was going to leave the shop with a short cage G-- D---- it!
Needs a couple of finishing touches, but it should work fine.
What a pain! :rofl:



http://photos-d.ak.fbcdn.net/hphotos-ak-snc3/hs151.snc3/17853_232147412922_521152922_3299858_3534216_s.jpg
 
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4130biker

4130biker

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johnbryanpeters said:
Of course, the steel cage is now a soft as overboiled pasta...

Next we need the ride report.
Click to expand...
True, but I'm guessing it will work fine. I'll let you know.

-although- I did "guess" that welding the new xt cage would work..
 
4130biker

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Holy crap- what an easy solution! My old cage is melted, otherwise I'd try it.
 
Icantdrive65

Icantdrive65

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Mar 21, 2005
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Before I embark on a project, I put it off for a few days to see what my subconscious can come up with. Sometimes I am amazed with the results and sometimes I kick myself for not getting a job done. Drilling the cage is one of those bright ideas that would not come to me until the brain had mulled it over on the back burner for a while. I have a few parts that are bouncing around the back of my brain right now.
 
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freeridefool

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Jun 17, 2006
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I totally dig it. I love the super super short cage that you welded. Im always trying to save, make new rear mechs with all my old ones. I currently am running an ancient 105 with a cage off something else. I also really like the drilling idea.
 
4130biker

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Icantdrive65 said:
Before I embark on a project, I put it off for a few days to see what my subconscious can come up with. Sometimes I am amazed with the results and sometimes I kick myself for not getting a job done. Drilling the cage is one of those bright ideas that would not come to me until the brain had mulled it over on the back burner for a while. I have a few parts that are bouncing around the back of my brain right now.
Click to expand...
Waiting was probably a good idea in my situation- two really good ideas popped up here after I did it :)
w00dy said:
Is it me or is the end result even shorter than a regular short cage?
Click to expand...
You may be right, it's really short. I went off of my very old xt short cage that I had and copied it. Unfortunately it's so old that it wouldn't bolt up to the newer xt, so I used it for practice welding. Now when I get my Howler built up, I'll ride it and let you guys know how well it works.
freeridefool said:
I totally dig it. I love the super super short cage that you welded. Im always trying to save, make new rear mechs with all my old ones. I currently am running an ancient 105 with a cage off something else. I also really like the drilling idea.
Click to expand...
Thanks! I have fun with it too since I have a hard time throwing down for something that will just get bent on a rock somewhere by me. Or cut apart :think:
 
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