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PostPosted: Wed May 15, 2013 9:09 pm 
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Joined: Tue May 14, 2013 3:59 pm
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If you are intersted in having a cracked aluminum frame repaired, then read on.

1) Dissassemble and clean the entire frame with a good cleaning solution like micro 90 or simple green. Once all grease and grime is gone, dry it thouroughly.

2)DO NOT USE ANY FORM OF GRINDING OR MEDIA BLASTING!!!
Strip the paint off all the way around the cracked area so that there is about 3 inches from any portion of crack to any paint. Chemically remove the paint. Chemical/liquid form of paint remover is key! Once the area is clean of any paint, wash with soap and water to remove the stripper.

3)Drill the ends of the crack out with about an .125" or 3mm drill. Debur the drilled holes using a small chamfer tool or a countersink.DO NOT USE A FILE OR SANDPAPER!!!

4)Take to your local electro plating shop and have them Ultra High Vacuum clean the frame and wrap it in foil. When you return to the platers to pick up the frame, be sure to bring hospital type clean room gloves with you. When you get the frame back, and before you leave the plating shop, PUT ON THE CLEAN SURGICAL TYPE RUBBER GLOVES and inspect the crack and around the crack up to the paint and verify it is clean.

5)Take the frame to a Ultra high vacuum experienced tig welder and request them to weld the frame for you. Make it known the cleaning procedure you have had done to the frame. An EXPERIENCED ultra high vacuum tig welder should be more than happy to weld.


Last edited by webphut on Thu May 16, 2013 3:49 pm, edited 2 times in total.

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PostPosted: Wed May 15, 2013 9:44 pm 
Retrobike's #1 Comedy Genius
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And your point is, caller..........?


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PostPosted: Wed May 15, 2013 11:47 pm 
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Joined: Tue May 14, 2013 3:59 pm
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My point is:

I noticed forum threads on cracks in the seat post mount on GT XCR I Drive frames, but none so far on how to repair the crack.

With this in mind, I thought it might be nice to have one that not only worked on the GT XCR I Drive bike frames but all aluminum frames.

:)


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PostPosted: Thu May 16, 2013 12:09 am 
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PostPosted: Fri May 17, 2013 8:34 pm 
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Location: Herts UK
webphut wrote:
An EXPERIENCED ultra high vacuum tig welder should be more than happy to weld.



Don't mean to offend but what is the source of this?

TIG = tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by an inert shielding gas (argon or helium) so no vacuum to be found.

For this reason alone I would question your other statements, yet the section to be welded need to be clean but to the extend that you descibe.

The following is quoted from the Lincoln electric site - USA (?) manufacturer of TIG equipment.

To overcome these challenges, operators need to follow the rules of thumb and equipment-selection guidelines offered here...

Base-metal preparation: To weld aluminum, operators must take care to clean the base material and remove any aluminum oxide and hydrocarbon contamination from oils or cutting solvents. Aluminum oxide on the surface of the material melts at 3,700 F while the base-material aluminum underneath will melt at 1,200 F. Therefore, leaving any oxide on the surface of the base material will inhibit penetration of the filler metal into the workpiece.
To remove aluminum oxides, use a stainless-steel bristle wire brush or solvents and etching solutions. When using a stainless-steel brush, brush only in one direction. Take care to not brush too roughly: rough brushing can further imbed the oxides in the work piece. Also, use the brush only on aluminum work-don't clean aluminum with a brush that's been used on stainless or carbon steel. When using chemical etching solutions, make sure to remove them from the work before welding.
To minimize the risk of hydrocarbons from oils or cutting solvents entering the weld, remove them with a degreaser. Check that the degreaser does not contain any hydrocarbons.


Last edited by 02gf74 on Sat May 18, 2013 10:43 am, edited 1 time in total.

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PostPosted: Fri May 17, 2013 10:05 pm 
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Joined: Tue May 14, 2013 3:59 pm
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02gf74 wrote:
webphut wrote:
An EXPERIENCED ultra high vacuum tig welder should be more than happy to weld.



Don't mean to offend but do you kinow what you are talking about?

TIG = tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area is protected from atmospheric contamination by an inert shielding gas (argon or helium) so no vacuum to be found.

For this reason alone I would question your other statements, yet the section to be welded need to be clean but to the extend that you descibe.

The following is quoted from the Lincoln electric site - USA (?) manufacturer of TIG equipment.

To overcome these challenges, operators need to follow the rules of thumb and equipment-selection guidelines offered here...

Base-metal preparation: To weld aluminum, operators must take care to clean the base material and remove any aluminum oxide and hydrocarbon contamination from oils or cutting solvents. Aluminum oxide on the surface of the material melts at 3,700 F while the base-material aluminum underneath will melt at 1,200 F. Therefore, leaving any oxide on the surface of the base material will inhibit penetration of the filler metal into the workpiece.
To remove aluminum oxides, use a stainless-steel bristle wire brush or solvents and etching solutions. When using a stainless-steel brush, brush only in one direction. Take care to not brush too roughly: rough brushing can further imbed the oxides in the work piece. Also, use the brush only on aluminum work-don't clean aluminum with a brush that's been used on stainless or carbon steel. When using chemical etching solutions, make sure to remove them from the work before welding.
To minimize the risk of hydrocarbons from oils or cutting solvents entering the weld, remove them with a degreaser. Check that the degreaser does not contain any hydrocarbons.


Your question says a lot. Thank you for clarifying what I suggested.


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PostPosted: Sat May 18, 2013 11:47 am 
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bloody hell we need to change our ally welding process,s at work weve been doing it the same way for 60 yrs and have never had a problem. we sent parts straight from the punch to the welding shop without any cleaning or degrease.any repairs to motor bike frames bike frames are always ground back or bead blasted


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PostPosted: Sat May 18, 2013 4:28 pm 
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THWANG-666 wrote:
bloody hell we need to change our ally welding process,s at work weve been doing it the same way for 60 yrs and have never had a problem. we sent parts straight from the punch to the welding shop without any cleaning or degrease.any repairs to motor bike frames bike frames are always ground back or bead blasted



so now you know how to do it properly - the wonders of the internet.!! :roll:


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PostPosted: Sun May 19, 2013 3:09 pm 
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Joined: Thu Jul 07, 2011 9:42 pm
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Location: crawley
My alloy Zaskar / Sts / alloy wheels have all been dropped off at my local welders in "used" state

Then they were welded and returned to me in the same state as I gave them


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PostPosted: Mon May 20, 2013 3:42 pm 
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Joined: Tue May 14, 2013 3:59 pm
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LOL,
I use to use grinding wheels and sandblasters to remove paint. Then I would just wipe it down with acetone and throw a bead over it. That worked great right up until some one with a bike frame came in and asked me to weld it. My weld had failed. But an old timer who had welded pretty much most everything there is to be welded gave me his fail safe recipe to welding those easy 5 minute weld jobs to all kinds of government work that never the less come around to bite you in the arse. This is why I posted the lengthy prep on the forums, because it has never failed me and it is used by most UHV parts, chamber, tool manufacturers.
On a different note, I have found that no matter what the welding job, The prep is usually the determining factor of how nice a weld comes out. Try to weld aluminum that has been blasted and It is 50/50 that the weld will be nice. You can have a weld that flows like butter if you are lucky. Most times though, it is ugly, black, and smoky. You need to stop and clean the tungsten because of all the crap that got embedded in the metal from the blasting process. Then if you are able to get past that, then you have to get the puddles to jump and if there is yuckies in the puddles, chances are you will have some serious ugliness happening to get the puddles to bridge.
As for the zaskar sts wheels, the welder most likely stripped the weld effected area with chemical paint remover and welded it. Though he had given back to you in dirty form, I would have had the wheels uhv cleaned out of professionalism.
Ok Im done. I am tired. See you on another thread.


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