Adding a disc boss- Mtbr.com
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  1. #1
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    Adding a disc boss

    Possible to do it myself?
    I think you can buy the boss and just braze it on with silver solder.
    Frame is steel, tange prestige.
    Gonzo, what do you think?
    How would you align it?

  2. #2
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    Quote Originally Posted by thebronze
    Possible to do it myself?
    I think you can buy the boss and just braze it on with silver solder.
    Frame is steel, tange prestige.
    Gonzo, what do you think?
    How would you align it?
    A little research and now I know:
    Ceeway.com has the part, looks like about $5.
    Propane or Mapp torch is all you need for heat source.
    Silver braze is cheap and easy to use.
    Mitering a steel tube with a file is a pain in the ass.
    frame builders rock.
    pics coming soon.

  3. #3

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    if you really wanted to do it yourself, here's what you'd need

    universal disc brake tab braze-on: SABA part 808 on this chart --



    disc tab braze-on alignment tool available from Henry James: https://www.henryjames.com (link is down temporarily)

    if tab is CrMo alloy: brass rod
    if tab is Alu: silver rod
    if tab is Stainless Steel: silver rod

    grind tab to mate tangentially with chainstay in position as dictated by alignment tool.

    braze properly with good radius on fillet

    check alignment

    if aligned, coat and install parts and then go RIDE.

    I would suggest using an angular tubing brace, perpendicular to the plane on which the disc caliper mounts, between the chainstay and seatstay on the caliper mount side.

  4. #4
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    Quote Originally Posted by gonzostrike
    universal disc brake tab braze-on: SABA part 808 on this chart --
    disc tab braze-on alignment tool available from Henry James: http://www.henryjames.com (link is down temporarily)
    Got the boss from ceeway yesterday, great service.
    Not sure I need the alignment tool for one job.
    Was told silver or brass rod, silver is better since it melts lower...
    thx

  5. #5

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    alignment tool

    the alignment tool isn't a "production" part.

    it's a necessity.

    that is, if you want your brakes to work.

    the caliper's mount tabs have to be aligned in 3 dimensions relative to the the rear axle. how do you plan to do that?

  6. #6
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    Quote Originally Posted by gonzostrike
    the alignment tool isn't a "production" part.

    it's a necessity.

    that is, if you want your brakes to work.

    the caliper's mount tabs have to be aligned in 3 dimensions relative to the the rear axle. how do you plan to do that?
    I guess no one has ever brazed on a disc boss without an alignment tool?

    What did they do before the tool came out I wonder?

    It must be impossible to fabricate any type of guide or rule to do the same job, right?

    Why are you so negative?
    Do you really think what you do is that important and exclusive?
    Why dont you offer something positive instead of being an ass?

    Funny how 3 diff frame builders who have offered to sell me the disc boss said I dont need an alignment guage.

  7. #7

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    "being an ass"?

    my post speaks for itself.

    you can align it by eye, go ahead. I'm trying to save you time & $$, you think I'm pi$$ing in your ear.

    the alignment tool isn't even expensive, and it ensures perfect alignment.

    also, silver rod is insufficient for steel/steel brazing of structural parts. it's okay for water bottle bosses and cable stops, but not for structural joints. too soft.

    be prepared for overheating issues. the solution isn't to use silver, but to know how to braze.

    I have reason to doubt the sincerity of your statement that framebuilders have told you you don't need the alignment tool, especially given that you don't have frame building experience.

    I'm sorry you think I'm not being helpful. I guess it's a perspective issue.

  8. #8
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    Quote Originally Posted by gonzostrike
    I have reason to doubt the sincerity of your statement that framebuilders have told you you don't need the alignment tool, especially given that you don't have frame building experience.
    GS, you just have an abrasive way of coming across, very know it all-ish for an amateur frame builder.

    All I can say is that the builders i've been talking to say I dont need the tool, if you dont believe me I cant help that, you can email me and I'll get you in touch with them if you feel thats necessary. I agree the tool would help, but if it costs more than is feasible, why bother, i'm not going into production or plan on doing this for anyone else.

    Dont take this the wrong way, but I feel that frame building is just a part of working with metal, its not rocket science, its basic welding and machine shop technology. Its very easy for anyone to pick up the fundamentals and produce something very functional.

    thanks for the advice.

  9. #9
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    Quote Originally Posted by thebronze
    I guess no one has ever brazed on a disc boss without an alignment tool?
    Mike T. did it himself years ago as memory serves. As I recall from his description posting on here (about four or five years ago), he used the caliper and disc rotor itself to position the tab against the frame correctly, then tack welded it in place, and then brazed it up afterwards. The alignment tool was the ol' mark one eyeball. Of course mike's not a framebuilder, just a retired machinist/auto mechanic as memory serves, so what would someone with a couple decades of on-the-job experience with metal know about welding stuff straight without an alignment tool eh?


  10. #10
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    Quote Originally Posted by DeeEight
    Mike T. did it himself years ago as memory serves. As I recall from his description posting on here (about four or five years ago), he used the caliper and disc rotor itself to position the tab against the frame correctly, then tack welded it in place, and then brazed it up afterwards. The alignment tool was the ol' mark one eyeball. Of course mike's not a framebuilder, just a retired machinist/auto mechanic as memory serves, so what would someone with a couple decades of on-the-job experience with metal know about welding stuff straight without an alignment tool eh?

    That was my plan, i've scrapped the project for now since i've got a soulcraft coming in. The conical washers and spacers that align the caliper provde a little room for error.
    If only Dekerf would sell his disc boss braze on's the job would be so much simpler.

  11. #11
    Doesntplaywellwithmorons!
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    why not get a bolt on mount adapter?

  12. #12
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    Quote Originally Posted by DeeEight
    why not get a bolt on mount adapter?
    Not much fun to do, its an eyesore, probably weighs alot more...?
    Also the frame has breeze drop ins which are cup like and wont allow anything to bolt flat to the outside of them.

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