Advertise on Bikeforums.net



User Tag List

Results 1 to 12 of 12

Thread: Flux

  1. #1
    Junior Member
    Join Date
    Mar 2008
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Flux

    I've built 6 lugged steel frames over the last two years, and my technique is getting better. Silver flows where I want it, and my brass fillets are starting to look like they're supposed to. But I still spend way too much time removing the flux. Are there any secrets to this? Which fluxes are the best for silver and brass?

  2. #2
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,744
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jimmitch View Post
    I've built 6 lugged steel frames over the last two years, and my technique is getting better. Silver flows where I want it, and my brass fillets are starting to look like they're supposed to. But I still spend way too much time removing the flux. Are there any secrets to this? Which fluxes are the best for silver and brass?
    Are you soaking the flux off? Heat helps.

  3. #3
    Junior Member
    Join Date
    Mar 2008
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I usually put the joint under hot water in a sink for a few minutes - that takes off the "unglazed" stuff, but I'm still usually left with chunks of hard, glassy material that I have to chip, sand or file off.

  4. #4
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,744
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    that's why people soak the flux. I'm impatient and usually take it off with a file. There are chemicals that will do the job, but that's a fairly involved process.

  5. #5
    Old fart JohnDThompson's Avatar
    Join Date
    Nov 2004
    Location
    Appleton WI
    My Bikes
    Several, mostly not name brands.
    Posts
    12,996
    Mentioned
    11 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jimmitch View Post
    I've built 6 lugged steel frames over the last two years, and my technique is getting better. Silver flows where I want it, and my brass fillets are starting to look like they're supposed to. But I still spend way too much time removing the flux. Are there any secrets to this? Which fluxes are the best for silver and brass?
    What flux are you using? In my experience, the Gasflux "type B" blue paste flux works better than any other I've tried and is by far the easiest to remove.

    You can buy it from Henry James Bicycles if your local welding supply store doesn't carry it.

  6. #6
    Banned
    Join Date
    Aug 2005
    Posts
    5,117
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I just use silver flux, but from what I hear of brass, the glassy hard stuff is non-water-soluble. So just be sure to ask your supplier for the water soluble stuff, or buy the stuff sold by Henry James, or other bike suppliers since it will all be water soluble. The stuff that requires chipping off can lead to damaged tubes, and is a royal pain. Just in case you are using that stuff on something other than a bike, they make a useful air tool that fires out a hedgehog's worth of spikes for rattling off the flux.

    If you have the right flux, then you just need enough water contact. Something like a wheelbarrow, or a tarp supported on a frame so you can get the whole frame wet long enough to fully loosen the flux. Take some of your glassy flux chips or a small part and immerse in warm water for an hour or so and see if the flux softens, if it doesn't you need to change your flux.

  7. #7
    Senior Member
    Join Date
    Mar 2007
    Posts
    6,094
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    One of the nice things about silver brazing is that you can get flux that soaks right off. I use the stuff Henry James sells. A ten minute bath in hot water is generally enough to get rid of every trace of flux. Cold water takes 30-90 minutes, in my experience. I did once use a file to remove flux. I still haven't gotten that file completely clean.

  8. #8
    Junior Member
    Join Date
    Mar 2008
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks, all. It seems like I should try to get some Gasflux Type B blue stuff and try it out. Does anyone besides Henry James sell it online? I'd order from Henry James but their website is pretty cumbersome.

  9. #9
    Senior Member
    Join Date
    Mar 2007
    Posts
    6,094
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    You've really just got to call them. You will be well taken care of.

  10. #10
    Old fart JohnDThompson's Avatar
    Join Date
    Nov 2004
    Location
    Appleton WI
    My Bikes
    Several, mostly not name brands.
    Posts
    12,996
    Mentioned
    11 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jimmitch View Post
    Thanks, all. It seems like I should try to get some Gasflux Type B blue stuff and try it out. Does anyone besides Henry James sell it online? I'd order from Henry James but their website is pretty cumbersome.
    Unless you already have an account with them you'll have to call them to place an order.

    If you're using brass you want the type B paste flux.

    If you're using silver you want the type U paste flux.

    HTH...

  11. #11
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Just want to chime in here to reinforce the need to get all the old flux off the frame, inside and out. Hot water is the key in my experience. Flux is an acid and if you don't get it all off it can attack the paint and even the metal.

    On one of my first frames I removed the flux off the outside of the frame using sandblasting - flux remained on the inside. Painted the frame and rode the crap out of it for one season. Started to notice the paint was bubbling up at the lug edges; the acid in the flux was migrating though pin hole voids in the braze joint and attacking the paint and most likely the metal as well. From then on I started to properly soak each joint to make sure the flux is properly removed.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  12. #12
    Senior Member Sangetsu's Avatar
    Join Date
    Jul 2008
    Location
    東京都
    Posts
    366
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    I've had good results with a product called Handi-flux. I used to use it as when I worked as a jeweler, it is made for the manufacturing of gold and silver jewelry, but I've also achieved very good results when using it on steel.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •