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Discussion Starter · #1 ·
As I've posted previously, the left side seat stay is cracking just below the stay/rocker pivot on my 07 Moment. Since it was purchased used I have no warranty so I'm going to tear it down and try and have it welded before it completely lets loose. Since the frame is going to be torn down, I'm debating on whether or not to strip off the powder coat and have it bead blasted and polished. Anyone ever done this and if so any pics?

Thanks

E
 

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i thought they were all anodized and i'm not sure how you strip that off or if it can even be done. anodizing changes the top level of the aluminum. i think you would technically have to strip some of the aluminum away with bead blasting and that doesn't sound like a god idea here's something i saw on a thread before

http://forums.mtbr.com/showthread.php?t=547944
 

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Discussion Starter · #3 ·
Damn, I hate it when you're right. Sounds like Greased Lightning is the trick. Probably going to give it a try since I don't have much to loose. Thanks for the link Q.
 

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qbert2000 said:
i thought they were all anodized and i'm not sure how you strip that off or if it can even be done. anodizing changes the top level of the aluminum. i think you would technically have to strip some of the aluminum away with bead blasting and that doesn't sound like a god idea here's something i saw on a thread before

http://forums.mtbr.com/showthread.php?t=547944
qbert- Which Cambridge are you from, New York, Mass, or another?
 

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Hum, interesting.
Yea, you can strip annodizing. Annodizing does alter the chemical composition of the very outer layer of aluminum, however, it also adds about 0.001" of material. The stripping process is pretty effective and essentially removes this 0.001" layer. The odd thing is that when you then re-annodize the material it never seems to look quite as nice as the first time. Perhaps we should have done a polish first.

you cant remove annodizing by bead blasting. The anno is too hard. IT must be removed with the electro-chemical process (the stripping process that is). Doing the stripping has also been about the same price as doing the annodizing.

Just realize all the bearing surface tolerances are expecting this 0.001" additional anno thickness.

More importantly, what is of concern is the welding you plan to have done. If I were you I would probably fix the thing myself as well. But there are some concerns.

right at the weld joints you will have to remove the annodizing. Perhaps you can media blast away the anno right in this area if you are good with a media blaster. The problem is the anno is so hard so as bits of it finally start to wear off, you start to erode the actual parent metal underneath.... so by the time you get all the anno off you have a potential to remove much more actual aluminum than you want. Hope that makes sense.

the other bigger problem may be the HEAT TREATING. The flavor of aluminum that mtn bikes use requires a heat treating process to bring the welded area back to full strength.
unless you do this you are going to have a significantly weaker zone than the original part. So visually, you THINK you have repaired the crack, but in reality you have set yourself up for a potential catastrophic failure. Talk to the person doing the welding about this. MAybe it is possible to add some 6061 almuinum to the area to 'beef it up' then you may be able to get away with not heat treating it.

There are more details I can give ya if you are interested... I think I have rambled on long enough.
good luck, let us know what you plan to do.
 

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Discussion Starter · #6 ·
Ventana, thanks for all of the info. Based on the little research I have done, stripping the ano no longer seems to be a viable option. I had read that Greased Lightning will remove ano but is mostly used on small parts and not something as large as a bike frame. I had not previously considered the effect that removing the ano would have on the pivot bearings, and you make a good point and probably the best reason for not removing the finish. Now back to the welding. The crack is currently only a hairline, running the entire width of the stay and protruding only about 1/2 mm into the stay. I am aware that when welding aluminum, it must be heat treated. I was hoping that since the crack is so minor that all it would take to repair is a single weld across the crack. Regarding your comment about adding 6061 to the area. Are you referring to some sort of patch placed over the area? In your opinion, considering my description of the crack, that this area would still need to be heat treated if welded? Thanks again for the help.

E
 

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ricthedick said:
Ventana, thanks for all of the info. Based on the little research I have done, stripping the ano no longer seems to be a viable option. I had read that Greased Lightning will remove ano but is mostly used on small parts and not something as large as a bike frame. I had not previously considered the effect that removing the ano would have on the pivot bearings, and you make a good point and probably the best reason for not removing the finish. Now back to the welding. The crack is currently only a hairline, running the entire width of the stay and protruding only about 1/2 mm into the stay. I am aware that when welding aluminum, it must be heat treated. I was hoping that since the crack is so minor that all it would take to repair is a single weld across the crack. Regarding your comment about adding 6061 to the area. Are you referring to some sort of patch placed over the area? In your opinion, considering my description of the crack, that this area would still need to be heat treated if welded? Thanks again for the help.

E
can you post some pics? that might help someone make an edumacated guess
 

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Discussion Starter · #8 ·
Yeah I know, this thread is meaningless without pics. I'll try tonight but the damn crack is so small I'm not too sure it will even be visible.
 

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Discussion Starter · #10 ·
So how did you remove the ano? Did you have any issues reseating the pivot bearings or did you leave the ano on where the bearing sits?
 

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ricthedick said:
So how did you remove the ano? Did you have any issues reseating the pivot bearings or did you leave the ano on where the bearing sits?
I used Mr.Muscle sewer cleaning liquid with piece of old t-shirt.
Put liquid on piece of cloth and let be over ano for 2-3minutes
Take rag off and wipe surface with damp(water) clean cloth very carefully.If you leave any of stuff on frame it will eat aluminium. Rinse and wash with lots of water.
Repeat until aluminium is bare.
You can use abrasive wax to get rid off ugly dark spots on frame.
Do NOT forget use safety glasses and rubber gloves .
Do it outdoors or well ventilated room.Vapors and liquied itself are nasty.
I did not polish it but just brushed frame,no wax was added.Using wax you achieve chrome like shine that needs regular waxing to keep that shiny look.I personally preferred rawmetal.
You might want to try that method on something small object
like cranks or handlebar,just to see how it goes.
I did not remove bearings while deanodizing however i changed them to new ones before
building bike together.

Hey i guess could do it my bronze ano Nicolai too....
 

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ricthedick

I've done this many times to frames. There's a really easy way to do this...

Ano is simply a "stain" or dye that goes into the tiny pores of the metal.

Do a search for anodizers in your area, or more commonly called "metal finishing". Many of these place will anodize things other than bike parts. Strip the frame into front/rear triangle.
Those places have a "strip tank" which will (in about 1 second) take off your old ano color.

If you polish the frame first & then paint, your frame color will really stand out & glow.

There is a Powdercoat Q & A thread currently going in the general section. LenMcC really knows his stuff about PC.

I stripped my frame, polished it & then powdercoated it candy red & it glows!
Good luck & post your pics when done.
 

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Hey man you should give Donald a call at Ellsworth he may be able to help you out before you get that welded.
760 788 7500 ex 206
 
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