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Brev Campagnolo Bike Frame
#1
My neighbor has a crack in the lower rear wheel mounting plate that he wants me to weld. I've searched for the frame specs to no avail to assertain the metal spec. I think its a stainless blend of some sort but not sure. Any information will be most helpful.

Also, I have read that if a frame is cracked, it should not hit the road again.

Thanks,
Doinok
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#2
Stainless frames are fairly rare, but they do exist.
Are you basing your assumption that it is a campagnolo frame on what is stamped on the "dropout" (the plate that the rear wheel bolts to where the frame tubes come together)? If so, it may just be that the dropout itself is campagnolo. They make this part for use by other frame builders. If so, it is probably a fairly high quality frame made of some version of Cromoly steel (http://en.wikipedia.org/wiki/41xx_steel). This is generally TIG welded.

Maybe some of the engineers on this list can give you better advice on how to determine stainless from cromoly or another steel type.

Bike frames can often be repaired by welding, but it really depends on the location and type of break. If you have no experience with bike frames, maybe would be good to show it to someone who does. But no reason that this can't be done per se.
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#3
Could we have a picture of the frame and the part that needs welding.

As well as being TIG welded, frames are also brazed, sometimes the dropouts, bottle bosses, brake bosses etc. are brazed on, even if the main tubes are tig welded. If the dropout is broken, you would normally braze on a complete new one.

Steel frames are almost completely repairable, you can replace whole frame tubes if necessary, and can be ridden once properly repaired, whether or not it's economical is another matter. Smile Whereas aluminium frames are pretty much scrap if cracked or broken.
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#4
I doubt that it is a Campy frame.

http://www.retrobike.co.uk/forum/viewtopic.php?t=101097
Nigel
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#5
Thanks to all who replied. I agree, this is just a campy part on the frame. The magnet test indicates it is steel (Reynolds Tube for sure) so I will braise the crack since all I have is a MIG rather than TIG welder.

Regards,
Doinok-Oregon
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#6
(09-12-2012, 10:50 PM)doinok Wrote:  Thanks to all who replied. I agree, this is just a campy part on the frame. The magnet test indicates it is steel (Reynolds Tube for sure) so I will braise the crack since all I have is a MIG rather than TIG welder.

Regards,
Doinok-Oregon

DON'T !!!!

The drop is brazed into the frame, trying to weld it will result in brass melting into the crack.

Heat it up, and remove the drop out from the frame, then decide if you can weld it.
Nigel
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#7
how about a picture of the crack, may better help us give you the right path to go.
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#8
(09-13-2012, 12:28 AM)nfmisso Wrote:  
(09-12-2012, 10:50 PM)doinok Wrote:  Thanks to all who replied. I agree, this is just a campy part on the frame. The magnet test indicates it is steel (Reynolds Tube for sure) so I will braise the crack since all I have is a MIG rather than TIG welder.

Regards,
Doinok-Oregon

DON'T !!!!

The drop is brazed into the frame, trying to weld it will result in brass melting into the crack.

Heat it up, and remove the drop out from the frame, then decide if you can weld it.
Doinok. Please follow Nigels advice. Old welder and metallurgist here... been there on my own.
Make sure to heat-sink the dropout and wet rag-wrap the stays for the paints sake. Having a Campy frame part indicates very high quality.
Wheelies don't pop themselves. (from a QBP fortune cookie)
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#9
Quote:Heat it up, and remove the drop out from the frame, then decide if you can weld it.

If you remove the old drop out, you may as well replace it with a new one. Try here: http://www.henryjames.com/productlug.html#roadhorDO or try Google for "Bicycle Frame Building Supplies", failing that, you could contact some frame builders and ask if they will sell you some drop outs for you to DIY.
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