brazing question

Discussion in 'General Bike Discussion' started by Kaleb, Jun 14, 2009.

  1. Kaleb

    Kaleb Guest

    1
    0
    0
    Im semi-new with building my frame, so this is probably a beginner's question.

    is it alright to completely braze my front triangle before I do anything to the rear triangle?

    I'm worried that reheating the seat lug is going to weaken the strength of the brazed joints.

    thanks, your input is appreciated.
     
  2. Bluedog

    Bluedog New Member

    3
    0
    0
    Kaleb you are smart to be asking questions before you make the mistakes. I have done it both ways and it's so much cheaper to ask the questions first.

    Are you fillet brazing or silver brazing? If you are fillet brazing then make sure that you use an externally butted set tube to have more wall thickness at the seat cluster. Or, you can use a sleeve to achieve this with a regular seat tube. I usually tack the front triangle and the chain stays at the same time and braze them all together. This means you only have to heat that bottom bracket once and typically the chain stays get pretty close to the seat tube in the back down there. The same applies here if you are silver brazing (with lugs). I always check alignment and then fit and braze the seat stays after and I always put it back into the jig to do this. It may also be helpful to get the seat stay to drop-out fit done before doing any tacking or brazing because it's easier to file and fit before they are brazed together. Also, backing up a bit, I always braze the rear drop-out to the chain stays first before any of this. I have a fixture that assists in this.

    If you are silver brazing then I wouldn't worry about weakening the seat lug but you have to careful with your heat when brazing the seat stays so as to not melt the silver out of your already done joint. It's not too hard, just be mindful.

    I hope this helps.

    Darrell