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  1. #1
    febikes
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    Best practice for TIG on bicycle tubing

    Miller has some information about welding on 4130 tubing.
    http://www.millerwelds.com/resources...me-Moly-Tubing

    How much of this applies to bicycle tubing? In what ways are steel bicycle tubings different from plain old 4130?

    There is some other information about 4130 at welding tricks and tips but as expected it is not specific to bicycle tubing.

    For example, do people use the same filler rod for all the various bicycle tubings and if so what rod material and/or size. Also, is the TIG machine setup the same for bicycle tubings as it is for 4130 or are there adjustments to make. ( i am starting out with a Hobart TigMate so really the machine I am using does not have a lot of room for adjustments.

    Other then mineral spirits and acetone, what solvents are people using after sanding and scotch bright?

    I will have some sample tubing scrap soon but I am sure not enough time exists for pointless trial and error.

  2. #2
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    It's pretty much 4130.

    Bike tubing, at least the non-stainless stuff, is mostly pretty much 4130.

    In general, that's a good article about basic welder setup. Many bike builders use ER70, many also use Weld-Mold 880t (good for joining dissimilar materials like stainless dropouts as well as standard mitered joints in 4130). ER70 will be available at any welding shop, 880t is pricier and harder to find.

    You will need to practice and mess with your settings until you find what you like. And after enough practice, the settings you prefer may change. It's more about the skill of the welder than the settings on the box.

    BTW, acetone is nasty and bad for you. Use denatured alcohol or just simple green/water after mechanically cleaning. That's plenty clean enough for steel.

    -Walt



    Quote Originally Posted by markfarnsworth
    Miller has some information about welding on 4130 tubing.
    http://www.millerwelds.com/resources...me-Moly-Tubing

    How much of this applies to bicycle tubing? In what ways are steel bicycle tubings different from plain old 4130?

    There is some other information about 4130 at welding tricks and tips but as expected it is not specific to bicycle tubing.

    For example, do people use the same filler rod for all the various bicycle tubings and if so what rod material and/or size. Also, is the TIG machine setup the same for bicycle tubings as it is for 4130 or are there adjustments to make. ( i am starting out with a Hobart TigMate so really the machine I am using does not have a lot of room for adjustments.

    Other then mineral spirits and acetone, what solvents are people using after sanding and scotch bright?

    I will have some sample tubing scrap soon but I am sure not enough time exists for pointless trial and error.
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  3. #3
    dru
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    'nuff said...

    Drew
    occasional cyclist

  4. #4
    febikes
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    Thanks!

    I am glad to know that acetone is not required. One thing I like about TIG is that while I am just getting started the process seems really clean. I like that the air quality in the shop is good and avoiding harsh chemicals is a good thing as well.

    I ordered some TIG FILLER ER70S-2 .035 and some 2% Ceriated TIG TUNGSTEN 1/16in.

    I am going to work on my technique a bit to make sure that I start with a focus on quality because no amount of practicing bad habits is going to help me on this road.

    In addition I have decided that one of the first things I will be building before actually going forward with a frame project is going to be a fixture for testing some simple joints. I am thinking about a simple design for testing a "H" weld with three tubes joined together into an "H" shape. A fixture can hold by passing solid rods through each of the vertical tubes in the "H". I plan to setup the fixture with a bottle jack so I can pull apart the welds and/or break the tubing. This will give me a way to measure my welding results as it hopefully improves and as I play with different techniques.

  5. #5
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    As far as cleaning, I dont use solvents.

    I use:

    an angle grinder with a flap wheel to miter tubes and clean scale from dropouts (worn/older flap wheels remove material slower which is good. A lower rpm grinder is good too)

    A drill with a medium wire brush (that doesnt score too much) to remove scale, rust and coating.

    A dremel with a slightly worn sanding barrel thing to remove the inside coating/scale before welding. (The inside weld area of the tubes need to clean of scale/black coating) Tiny steel dremel brushes are necessary for tight corners...

    A tip for strong welds:

    If I am welding .049 or larger, I always put a bit of chamfer, or "land" as I think its referred to, on the mitered edge. Not a sharp edge, but enough that the tube gets better penetration... For .035" its not as necessary or even possible. A little chamfer at the dopout weld areas helps too in many situations

    Most tungsten electrodes are radioactive, and can supposedly cause lung cancer if you dont keep a clean shop!

  6. #6
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    Quote Originally Posted by mattty
    As far as cleaning, I dont use solvents.

    I use:
    That is good advice. I will add this though. First, most tungsten nowadays is not radioactive. Only Thoriated tungsten is radioactive and the other types, cerated, lathanated, Zirconiated
    are not radioactive. Although I would still recommend not taking a big inhalation of the dust if you can help it.

    For truly clean pieces you need not only mechanical cleaning but chemical cleaning as well. This can be done in many different ways and you can use relatively harmless things like alcohol or even soap and water or a ultrasonic. Try this as a test. Clean your item as you are, then get a clean wipe and wipe with alchohol. There will be dirt all over your wipe and this contaminates welds to some degree.

    How clean do we need it? Well, obviously many good welds have been done on what would be considered dirty metal in high end welding situations but alcohol (or simple green as Walt recommended is safe and I feel better and get better results with a mechanical and wipe afterwards.

    Your cleaning methods are great. I do much of the same thing but I have some fancy assed stuff (like a really nice belt grinder). The sound of dremels and grinders drives me up the wall....
    All the best,

    Dave Bohm
    Bohemian Bicycles
    http://www.bohemianbicycles.com
    &
    http://www.framebuildingschool.com

  7. #7
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    I don't put much stock in the 'failure test' for TIG. Even a terrible weld is unlikely to break, so please don't rely on that. Poor welds will cause fatigue to happen more quickly, and a simple bench test isn't going to show you that.

    Definitely cut through your test welds to look at the penetration. Make adjustments to your settings and technique and try again.

    And by the time your welds are smooth and consistent, you're all but guaranteed to be making safe welds. And be sure to get feedback from expert welders because I'd trust them far more than I would a good 'test' result.

  8. #8
    febikes
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    Thanks!

    BTW; great welds and great design. In my book ByStickel welds are second to none.


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    Not true, but thanks. (I only show the ones where I managed to not screw up.)

  10. #10
    A crunchy treat
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    D.F.L. what do you use to hold your seatstays on the lathe while you mitre them?

  11. #11
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    Quote Originally Posted by Carrot
    D.F.L. what do you use to hold your seatstays on the lathe while you mitre them?
    Simple homemade aluminum plate held with a machining attachment, but you can fab almost anything to hold a plate with the cross-slide. I wouldn't seek out a machining attachment specifically for this, I just happened to have them.

  12. #12
    febikes
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    I did some welding practice this week. The following is the best result I have had so far. I don't really have access to any welding experts for in person advice so please let me know what you see and if possible give me some tips for improvement.


    More photos here:
    http://febikes.wordpress.com/2011/01...ding-practice/

    I was using a very simple Hobart Econo TIG machine (no pulse available on the machine). I had 1/16th ER70 filler rod and was moving the puddle into the filler rod in addition to sometimes pushing the rod into the puddle.

    My what should I be looking for in weld inspection and what sort of inspection checklist should I have?

    Thanks in advance.

  13. #13
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    1. there seems to be quite a bit of scale on there. If you havnt already, try pushing your CFH up to around 30 and your post flow up to 7-10 seconds (and keep the torch there while the argon is shielding it) This scale might also be attributed to too small of a cup size, having the electrode too far out, having the torch at a funny angle(which doesnt shield the puddle properly) Also, if you havnt already consider a backpurge setup that shields the back of the weld too

    2. those little volcanoes are a result of letting of the gas pedal too quickly, try feathering off the pedal

    3. try going in one direction. My rule of thumb is "U" forward. The puddle forms a little U shape where the open part of the U is the direction the puddle moves

    4. Almost always make a puddle and add filler to the puddle at an intermittent interval. (If you've burnt a little hole sometimes you have to shove the filler in there fast at a lower temp to keep from burning more)

    5 Use a welding sequence. Dont weld all the way around at once, you will over heat the thing and cause distortion.

  14. #14
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    More practice

    -Looks like things are getting too hot, or you're not getting shielding gas on the weld when it's still hot enough to react with the atmosphere. You may need to use less heat/move quicker, or work more on getting gas where it needs to go. Or both.
    -Make sure things are clean before you start (hard to tell from these pics, but it's worth saying again).
    -Get a gas lens for your torch if you don't already have one. Remember that more argon is not necessarily better - if you are pushing it too fast, you'll just generate turbulence that will suck atmosphere into the area you want shielded.
    -Play with your settings. A lot.
    -Learn to dab your rod into the puddle (sometimes you'll just run over it too, as you're doing, but it's good to be able to do both).

    Ideally you want fairly bright/shiny rainbow colored metal on the weld bead, not dark black/grey stuff (this slag is what you get when the steel encounters oxygen when it's still hot).

    Let me be clear, though, you are doing awesome. Those look way better than the first welds I did on bike tubing, that's for sure.

    -Walt

    Quote Originally Posted by markfarnsworth
    I did some welding practice this week. The following is the best result I have had so far. I don't really have access to any welding experts for in person advice so please let me know what you see and if possible give me some tips for improvement.


    More photos here:
    http://febikes.wordpress.com/2011/01...ding-practice/

    I was using a very simple Hobart Econo TIG machine (no pulse available on the machine). I had 1/16th ER70 filler rod and was moving the puddle into the filler rod in addition to sometimes pushing the rod into the puddle.

    My what should I be looking for in weld inspection and what sort of inspection checklist should I have?

    Thanks in advance.
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  15. #15
    febikes
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    Thanks!

    I will be getting a gas lens for the torch. Steve at BREW was a big fan of gas lens but I have not gotten one yet. The shop equipment is at a shared techshop but I am sure they will not mind if I buy my own gas lens and bring it with me.

    In terms of movement I think going faster might be the key. I found that I was often spending a lot of time on an area and not moving smoothly. Next time I can hopefully get the heat up quicker and then move along at a more steady pace plus feather the pedal when I stop.

    The Econo TIG does not have much in terms of settings. I can't adjust pre or post flow and there is no pulse. It seems to be a very basic unit with simple amp adjustment (i was set at 30 on the dial).

    When I get a TIG for my shop it will likely be a Miller but I feel the need to do some more practice before making a big buy.

  16. #16
    Old school BMXer
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    I understand that you can run the tungsten out further with a gas lense, but how far out from the gas lense cup is ideal?
    May the air be filled with tires!

  17. #17
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    +1 on what Walt said.

    It needs to be clean, inside AND out. If you have a heater/fan running, direct it somewhere else. Even a minor current will cause the argon to do weird things. Don't forget to breathe and relax when holding the torch. You shake less when your hand is relaxed.

    AND

    It may be your welding device.

    I had an Econotig for a little while. Welding .035 tubing was VERY difficult, as it's 'base' power was pretty hot and it didn't have much(read any) control down low. You don't need a pulse unit, you have a foot that can do more or less the same thing. A pulse will help you find a rhythm, but not make a nicer weld. Of course, it can be used to control the heat if set up properly, but it's not necessary. I have a pulse unit, and unless I was/am doing high production work (welding say, 100 turbo down pipes, in a jig, in a day) I never used it.

    On the EconoTig, Try using some smaller tungsten. I think the smallest I found was .040, which is very small, but it helped with the heat a bit. I made some acceptable welds in .035 stainless and titanium, but I had to move fast. I'd say, for learning. to weld use a .049 or .065 tubing.
    This way, you learn to see what a good bead looks and 'feels' like, after that the thinner stuff gets easier as you can move faster and think about what you are doing less.


    *edit*
    I have a Dynasty 200dx. Had it about 7ish years now, not a lick of problems. My only regret is not buying the 300dx when the prices were reasonable. I have use for the extra juice at least 10 times per year. (never bicycle related)

  18. #18
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    Quote Originally Posted by Brad Bedell
    I had an Econotig for a little while. Welding .035 tubing was VERY difficult, as it's 'base' power was pretty hot

    ...

    I have a Dynasty 200dx (now)
    Haha. I have had the exact same equip. I don't see how you're going to do thin stuff w/ an Econotig. It only goes down to 20A. I never could do thin sheet w/ it but it'll knock out race car roll cages from 0.095" tubing all day long The Dynasty makes doing thin stuff so easy you feel like you're cheating.

  19. #19
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    Dunno if this will help with the minimum-amperage issue, but I found that the non-radioactive tungsten required higher amperage to get the same result. This may help by artificially lowering your machine's output. Anybody else notice this?

    You're doing great. The overheating is a common issue when folks are starting out. Once you gain more comfort and experience, you'll use less pedal and will move more quickly.

  20. #20
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    Quote Originally Posted by D.F.L.
    Dunno if this will help with the minimum-amperage issue, but I found that the non-radioactive tungsten required higher amperage to get the same result. This may help by artificially lowering your machine's output. Anybody else notice this?
    Hey Steve,

    I noticed this too when using ceriated tungsten. Got to step on the gas harder vs thoriated. I also think it's not as bright and it's harder to see under the hood.
    Erik Rolf
    Ketchum, ID
    Visit the website @ http://www.alliancebicycles.com/

  21. #21
    febikes
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    The following is more practice that I did last night. This time I used 2% Ceriated 1/16in. The welder is actually a HOBART TIGMATE (not econotig). From the spec it sounds like minimum power is 20 amps and that is what I was using.



    You can click the photo above for a larger photo with more detail and/or use the following links for other recent examples.
    http://febikes.wordpress.com/2011/01/28/more-practice/

    With this attempt I spent more time with prep work. The miter was done on a grinding wheel but gaps were minimal. I cleaned the tubes with mineral spirits, wiped dry, and then used some scotch bright. I don't have emery cloth or files yet so this was the best prep I could do.

    I am using scrap tubing from Evil and Walt (big thanks for sending the scrap). The tubing here is .8mm.

    My short term shopping list includes getting some emery cloth and some good files. For the next attempt I plan to miter with grinding wheel, finish with files, and then clean with emery cloth and then simple green.

  22. #22
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    I'd recommend an amp setting always slightly above what your material can handle. This will give you reserve current when the material's heat sink is good and will prevent you from needing to linger in an area as your 20amps slowly heat up a thicker section to melting temp. You want to be able to modulate the pedal, rather than have it functioning as an on/off switch.

    While your weld has a lot of scale from excess heat, the beads actually look a little cold and lumpy. I'd guess that your amps were too low (I'll typically use 35-ish) and that you spent too much time trying to get the filler to flow.

    I just think you need practice time.

  23. #23
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    What you are doing and the way you are going about it is fun and inquisitive. Its pretty much the same way we went about it when we started. The very first time we fired up the welder, was preceded by some Google searches on "how to weld". In fact the guy that sold us the welder commented, "ehh its not too hard, there are about 3 things you never want to do. Outside of that its no big deal." So our Google searches where actually, '3 things not to do when welding'

    After weeks of practice, our welds looked just like yours. We had a hard time controlling heat, 'pushing' the weld puddle, and getting proper penetration. About 4 mos into our practicing we acquired a Miller Syncrowave 250 and then invited a welding instructor out for a weekend of instruction. THIS CHANGED EVERYTHING. The very first time I witnessed him run a bead, all the lights went on and I immediately realized the changes I needed to make. I'm posting the photo below as an example from our website. If I was at my home computer I'd post a comparable early weld photo that would look just like yours. It just takes some guidance. I'd recommend some personal instruction from someone who can help teach you. You'll be a better welder that same day

    www.HammerheadBicycles.com
    Austin's dirty little secret

    www.TrueFabricationBicycles.com
    Texas Born; Texas Bred

  24. #24
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    Thanks CBaron!

    I have looked some at Miller line of welders and am really thinking hard about getting a 150 STL. Getting my own welder would also provide me more time for practice because as ByStickel pointed out I really need some hood time.

  25. #25
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    Since welding practice is the topic....

    While saving up for a proper TIG machine, would it make any sense to buy a cheap MIG set up to mess around with in the mean time?

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