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-   -   Wrong kind of heat? (http://www.bikeforums.net/framebuilders/714959-wrong-kind-heat.html)

calbughjr 02-21-11 10:54 AM

Wrong kind of heat?
 
I'm trying to remove the dropouts on my 85 Schwinn Traveler. These are stamped, slot style dropouts. I thought I would be able to remove them by heating the joint until the filler started to melt, but was unable to get any filler to flow. The stays were cherry red when I stopped trying. Is MAPP gas not hot enough, even though the metal was? Another thing, there are these little holes in the stays, one on each of the seat and chainstays on the inside of the frame about an inch from the dropouts. Is there some sort of pin in there keeping me from disassembling?

sannerbikes700 02-21-11 04:12 PM

I think the problem is you're not able to adequately and simultaneously heat both joins on a dropout. For example, when you heat the seatstay/dropout to proper temp, then move to heat the chainstay/dropout to proper temp, the seat stay/dropout cooled and solidified.

If you don't care to keep the dropouts, slice a dropout in half so you can heat and remove each half, one at a time.


...Unless those dropouts are welded on, which I can't imagine being the case on an 85 traveler.

ftwelder 02-22-11 03:44 AM

heat the hell out of the drop but try to keep the stays cooler.

tuz 02-22-11 09:19 AM

I've never done it, but I can see why drops are hard to un-braze; there might be 1 inch of dropout plus brass inside the stays. Cutting the dropout will help, but I doubt air-mapp has enough heat. Plus keeping the dropout intact would help to find a suitable replacement, in order to preserve the geometry of the bike. And don't pull on the dropout while the stay is hot, it can easily break apparently. Some bikes do have pins (you should see it if you remove the paint and clean the metal), and even some had a tack weld!

Your best bet would be to setup some sort of forge... firebricks on a piece of angle iron?

Dave Kirk 02-22-11 10:25 AM

Maybe you have done this but just in case - you want to cut the dropout in 1/2 between the chain and seat stays so that there is a piece of the dropout hooked to each stay. Grab the dropout with some vice grips and position the frame so the dropout is low and then heat the dropout a good bit so the brass will flow out of the stay and onto the dropout. GENTLY wiggle the dropout with the vice grips. If you are heavy handed you'll break the end of the stay off. Wiggle it gently and you'll feel when the braze is all soft and the dropout part will slip right out.

By cutting the drop you make it so you need much less heat. If you were already doing this I apologize.

dave

NoReg 02-22-11 10:43 AM

Also Mapp or propane can have enough heat if you are able to contain it Once the drops are cut you canslide something over them to hold the heat in. A soft firebrick a can containing vermiculite, or some of the that rockwool insulation, though I haven't tried that myself.

Base your approach on one brick forge designs:

http://www.youtube.com/watch?v=qlKwhIuMdrM

calbughjr 02-22-11 10:15 PM

Thanks for all the info, I'll probably try cutting the drop as my first remedy. Im thinking the holes i saw were pressed in after the dropout was fitted, before brazing. Just got a nice pair of paragon track dropouts delivered today. Bottle opener on the non drive side, and a der. hanger. I'll keep you posted.

Chuck

unterhausen 02-23-11 11:49 PM

the holes have nothing to do with the dropouts, they are vent holes. The dropouts don't go in that far.

calbughjr 03-02-11 08:13 PM

thanks unterhausen. and to everyone else, thanks for all the info. after cutting through the dropouts i had much better luck. both came out clean and the slots are all cleaned up and ready for the new dropouts.


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