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  1. #1
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    Titanium welding questions

    Hi MTBR Framebuilding community,

    Been wanting to do this for quite a while now, watched all the instructionnal Ti welding videos on youtube and I'm just about ready to order some 1-1/4 x .035" Ti tubing to make a "XXX-Small dummy bike welding test" just for practicing and get comfy enough for eventually make the next bike on my list out of this material..

    I think I've got a pretty good idea of where I'm heading but before lighting up the torch I have 2 more questions that I hope some gurus out here are gonna be willing to answer :

    1- Can Ti tubing be notched with simple holesaws or I need those strawberry bikes holesaws ?

    2- Why do a fusion pass first ? Seen this on Flickr lots... Would this perform the same function as a root pass on a heavy-as-hell pipe ?

    Thanks for any inputs.

    By the way, big thanks to Rody Walter of Groovy for throwing up this video on Youtube:
    Fabricating a custom Ti welding cup - YouTube
    It's awesome that guys like you are willing to share knowledge like this.
    My #12 cups are ordered !

    Thierry

  2. #2
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    Hi Thierry,
    I've been practicing on the same size tubing. Regular hole saws are fine. Just be sure to clean thoroughly and then give the areas to be welded a good scrub with a dedicated stainless brush and then another wipe.

    I have found that the 1st pass seals the joint and has given me more consistent protection when filling the joint. When I tried to do it in one pass, I would get some darker straw and light blue. I haven't done a full frame yet, so I can't comment on how each pass helps control alignment.

    The puddle is bright and shiny like when welding stainless. I really enjoy welding it. You'll have fun!


    Titanium Fused by Zanconato Custom Cycles, on Flickr


    Titanium Filled by Zanconato Custom Cycles, on Flickr

  3. #3
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    The fusion pass does several things.

    1. helps make a heat bond between the two tubes and does some work in preventing a hole.
    2. absolutely ensures that you're getting a full penetration weld.
    3. It also makes a nice bed for you to lay down your second pass.

    in order for it to work correctly, your miters have to be tight all the way around. if they're a little loose, or you have a gap on top (or bottom) you *can* close the gap during the fusion pass by moving from the tight side to the loose side, but you're going to distort the non-mitered tube in the process.

    Completing a fusion pass helps but doesn't eliminate the possibility of bridging between tubes with your filler rod. Titanium is highly notch-sensitive. If you give it a stress riser, it's happy to crack out at that stress riser. Bridging is one way to make a frame that has a high likelihood of breaking. Leaving your second pass cold with a distinct toe is another.

    You definitely don't need Andy's cutters to cut it. Any old holesaws are fine. I run my mill around 160rpm with a fairly high feed rate. It's a bit grabby so make sure you're fixturing is rigid enough to handle it.

    Also, you can get away with a standard big gas lens and a #12 cup so long as you don't dwell too long or move so fast that you're outrunning your argon shield.

    Do a good job cleaning the tubing inside and out both mechanically (scotch brite) and chemically (acetone or denatured alcohol) before you weld. If you pull your filler rod out of the shield gas while you're welding, clip off the tip before making any more puddles. I also scotch brite and acetone the filler rod before I weld with it. It's supposed to be "clean" already, but even wiping it down before welding clearly shows that it's not. Scrubbing and wiping the rod has made a small improvement in the color to my welds (a faint halo in the haz to almost nothing at all)

    also, deburr your vent holes very well on both sides of the hole. this is something that I don't think is mentioned often enough. Leave a burr on there and you've got another stress riser - back to notch sensitivity.

    Good luck, have fun.
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
    flickr :: www.vertigocycles.com

  4. #4
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    Fabulous

    Sent from my LG-P769 using Tapatalk

  5. #5
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    WOW, thanks a million Mike and Sean, I wasn't expecting a complete answer like this in such a short time. This is sooo many good infos.

    Think I'm definately good to go with some hands on tests now !

    Cheers !

    Thierry

  6. #6
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    Happy to help. One other thing I thought of that drives me crazy. The tip of the filler tends to stick to the parent metal a lot more than steel. If you dip and the tip of the filler hits an area of the base metal that is not melted, it will stick. Be very deliberate with your dabs. I aim for closer to the center of the puddle, whereas with steel and aluminum I'm adding filler right at the leading edge. I tried doing it that way with titanium and the filler kept getting stuck just ahead of the puddle. I hope I'm making sense.

  7. #7
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    Quote Originally Posted by zank View Post
    Happy to help. One other thing I thought of that drives me crazy. The tip of the filler tends to stick to the parent metal a lot more than steel. If you dip and the tip of the filler hits an area of the base metal that is not melted, it will stick. Be very deliberate with your dabs. I aim for closer to the center of the puddle, whereas with steel and aluminum I'm adding filler right at the leading edge. I tried doing it that way with titanium and the filler kept getting stuck just ahead of the puddle. I hope I'm making sense.
    so true. titanium is super sticky and that's one of the reasons to do a fusion pass. It's all too easy to try to get in there for a dab and never quite get enough heat to get into the root of the joint.

    Alternately, you can keep the rod in the puddle and weld slightly hotter. Just setup the pulser go at it hot and aim each pulse at the leading edge of the last puddle. This isn't for everyone but it'll help keep your rod well shielded and eliminates the risk of pulling it out of the argon. I typically use 0.065" rod across all the centerlines (two passes with it on acute joints) and 0.045 on the sides. You don't have nearly as much space to fill on the sides and the 45 just lays flatter...just a personal preference, not necessarily a recommendation. It's also a good idea to really push the filler into the acute sides too and get as much built up in there as possible without having a cold toe. My only warranty frame to date had a cold edge (full penetration though). Bummer but lesson learned.

    Sean
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
    flickr :: www.vertigocycles.com

  8. #8
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    Got another question here,

    Can a guy weld 6AL-4V plate to 3AL-2.5V Tubing ?

    Seems like plate ain't too too available in 3-2.5.

    Thanks again.

  9. #9
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    You bet! All of the structural machined parts are 6/4.

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