Ask your WELDING questions here.

Discussion in 'The Garage' started by KTM640Dakar, Mar 5, 2007.

  1. KTM640Dakar

    KTM640Dakar Motorsick

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    Welding without using filler is called autogenous TIG welding. As you would expect the area that you weld will be slightly thinner than the parent tubes. You see many custom exhausts welded without filler. I guess as long as the reduction in cross section at the welds is stronger than the forces that the pipe will see than your golden.
    You will need the parts to fit up perfectly. So I wouldnt be without a cut length in your hand just in case you need to add a little filler to keep the gap filled.


    A good two stroke pipe can look like a piece of art.
  2. Strong Bad

    Strong Bad n00balicious

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    Stainless Steel......

    You don't have to be as careful about pre-cleaning as you do with aluminum, getting rid of any oily residue on the surface is what is most important. SS doesn't get the oxides on the surface that aluminum does that contaminate the welds.

    Go for full penetration and purge the back side. This will be really important on your pipe. Once you get it down, a newbie will have a hard time determining which was the backside.
  3. sakurama

    sakurama on an endless build

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    Hi guys,

    Thanks for the help so far. I got back to east for work and found a little time to get to my shop to practice with my own gear. I had been using a 3/32 tungsten but I had a pyrex diffusion lens I'd ordered but never tried so I put that on and it uses a 1/16" tungsten.

    [​IMG]

    Here's some early practice.

    [​IMG]

    The weld on the right is from two weeks ago - now I can see it's obviously scorching the shit out of the material. The others are my practice over the last day.

    [​IMG]

    Now after a few hours of practice I'm to here. The top one is my last weld last night before I went home. I think the middle looks a little cold but on the back I'm just getting full penetration. This is 35amps for .065 wall with 1/16" tungsten and .035 308 filler. Gas is 20 cfh with the lens. Towards the end I was trying to ride the peddle with the machine set a bit higher than I thought it needed (35 amps) so I could work on my manual control.

    I feel that I now have a good feel for the heat and puddle and I just need a few miles of bead under my belt to be consistent. It's much harder to weld tube than flat stock. I seem to be able to only do about 1/2" at a time so I'm trying to tie my welds together so it looks better but following the tube around and keeping the torch angle is tough. I need to brace my hand on something and that limits my ability to freely follow the tube.

    One funny thing I noticed: I really want to see the weld puddle so I get my helmet really close and it felt like I was spacing out or couldn't hold my concentration. It took a moment to realize that I was trying to look from 6" away and that, for the first time in my life, it was my eyes. I need to wear reading glasses I guess. I tried welding from father away which was fine but I really want to be super close to see.

    Anyway, feel free to offer some criticism.

    Gregor
  4. Davebert

    Davebert Too damn serious!

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    Get some cheater lenses for your welding hood. And wear reading glasses too if you need to. I am in the same boat. If you can see you will weld much better. :evil
    DB
  5. Schlug

    Schlug JockeyfullofBourbon

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    put something on and stay in that position.
    How are you bracing your torch? Your welds are wildly inconsistent in places. Are you using your middle finger to brace? In your class was she teaching you to walk the cup or freehand?

    I think-- and I'm a pipefitter, not an exhaust fabricator-- that a full pen, open butt weld with filler would be better than a fusion weld. Lots of guys can make excellent stainless welds, not so many can freehand a fusion weld.

    Of course you'll need a double flow metre for the argon tank and some hose, but you can plug the one end and fill from the other and use foil tape over the joint. Peel it back as you progress up the weld.

    I have very little experience welding something so thin. When we do .065 or .049 stainless it's usually done by an orbital machine unless it cannot.

    I flapper wheel on an end grinder will do all the cleaning you need.

    Make sure you get some cheaters. Any welding shop will sell them. Get two or three (they don't cost much) in differnt powers. If you can't see, you can't weld. Period. This isn't like a carbon stick weld when you can hear/feel it in.
  6. David R

    David R I been called a Nut Job..

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    Sakurama, your welds are getting better. You are not overcooking the filler as much. Doing beads on the pipe is good, now its time to cut the pipe and do it again. It will take less heat because the edges burn back real easy with stainless.

    Practice on butt joints and you will find out fit up is MOST important.

    Tack in 4 places, don't stop or start on tacks.

    Have fun!

    David
  7. Schlug

    Schlug JockeyfullofBourbon

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    put something on and stay in that position.
    You don't want him to tie into his tacks?

    I suppose I could see running over his tacks in this case...

    had to think about it for a second
  8. David R

    David R I been called a Nut Job..

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    I try to weld through the corners and weld through the tacks. stops and starts should be planned. If I am building something that has to be air or water tight, I make as few starts and stops as I can. Those and tacks are where I could get leaks.

    David
  9. fxstbiluigi

    fxstbiluigi crash test dummy

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    Instead of restarting where you stopped backup about a 1/4" or so fireup and everything will nice an hot when you come to where you stopped.
    By starting on a tac, rather than between tacs, you eliminate the number of tie ins' that need to be made.
    If you are using a fill wire fuse the wire to the side near the tac then without breaking the arc backup about 1/4" or so and start a puddle then when you come to where the wire is fused everything will be good and hot and flowing. The same method can be used if multiple passes are required to fill the joint.
  10. Toyanvil

    Toyanvil Adventurer

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    Tank ? I have a small tank 7"x 24" on my welder and a large 7"x 48" tank for Nitrogen, are they the same? I would like to make the larger one my welding tank and the smaller one my Nitrogen. :ear
  11. David R

    David R I been called a Nut Job..

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    You Will have to ask your gas supplier. One is probably 40 cf and one is probably 80 cf.
  12. ishdishwishfish

    ishdishwishfish Been here awhile

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    I've been having trouble getting penetration welding a tab to the frame neck of this chop I'm working on. Making a fork stop so that I don't get into any serious trouble.
    It's (I believe) a 120V, 24A gasless flux mig--harbor freight model. It's the step up from the really cheap one, bought used. Doesn't look like I can change the amp setting.
    So I'm trying to weld 7 gauge (IIRC) to the neck. It needs to be a longer tab, about an inch. The width of the weld is about an inch.
    I round out the tab to fit the neck, chamfer the end by going approx. 45 deg. half and half flat. Usually use a flap disc to prep, but did use a file to burr the edges later. Did have a little better pen. using the file.
    I'll get it tall prepped, tack the weld on once, then run the weld down the tab. I'm holding the tab in place with the negative, so flipping the mask down, turning on the torch, etc. gets in the way of a good tack. Then I'll run a weld down, usually all at once.

    It looks like it's only penetrating the chamfer section. I'll run a decent (for me at least) bead, but it still doesn't penetrate through the bottom. There are too many variables for me to figure out on my own: am I going too fast? Do I need a larger wire dia? try and eek out higher amperage (turn off everything else on that outlet) ? different chamfer? wrong prep? Don't mess with it and wait for the weld to cure? Please advise:evil

    I think I need to make the chamfer deeper angle, make the flat section shorter and be sure I get the flux down in there, go slow enough to pool.

    Scott.
  13. ishdishwishfish

    ishdishwishfish Been here awhile

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    Turns out that neck is cast iron. I'll have to try welding it to the bearing race.
  14. NitroAcres

    NitroAcres MotoBiggots Suck

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    Necks on motorcycles are Cast Steel...not cast iron.

    Bearing race is hard as glass..."Yer gonna put an eye out kid":D
  15. ishdishwishfish

    ishdishwishfish Been here awhile

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    Haha yeah we've made progress in that dept. Taking it in to get tigged. I need some other stuff done too, this guy's reasonable. Case of beer reasonable.
  16. NitroAcres

    NitroAcres MotoBiggots Suck

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    GoodCall, Bring him Good Beer and remember a case is 24, and he will remember you next time, I had a guy bring me a 12pack..he actually called it a "case"....:lol3
  17. GodOmelet

    GodOmelet Adventurer

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    Hi Everybody,
    I searched to see if this had been covered but didn't find anything, so here goes: I have been working on restoring a basket case 77 R100, and after doing everything on the laundry list Olds Cool guys could throw at me, I went on my maiden ride. Everything was going great, rebuilt Bings singing, idle and throttle performance good, etc.... until, when pulling up to a stop sign with a pretty lady at the crosswalk, low and behold the brand new clutch cable snaps.

    ...Or so I thought. After pushing it past the pretty girl, and another 1/4 mile home, I discover this (or a much less cleaned up version of this with more parts attached):
    [​IMG]

    So, really it looks like the circlip either came off or the PO forgot to put it back on, or for some random reason the cast aluminum just broke. I found an account of this happening to others on Duane Ausherman's website, and he was kind enough to reply to an email asking what can be done about it. He said they have been repaired by welding in the past, some even while on the bike... Nevertheless, I pulled the transmission, emptied the oil and cleaned it thoroughly. The local welding guru is game to fix it but would like to know which type aluminum rods are reccommended for BMW cast aluminum from this era. He decided the little "C" shaped piece was worthless and decided to build up material and bore it out for the lever pin. Anytakers on the rod selection? Thanks!
  18. David R

    David R I been called a Nut Job..

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    I think its cast aluminum of good quality. I would clean the aluminum and use 4043 pure aluminum.

    For cast I run the torch over the joint with no filler to get the junk out of the cast. Clean again and weld.

    You could use a carbon rod to keep the hole.
  19. GodOmelet

    GodOmelet Adventurer

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    Thanks David. I believe the welder is using copper to maintain the hole. He machined it to a couple thousandths bigger than the pin, but smaller than the hole on the other side, so that we would have some room to bore it out and make it exact. This guy is also a talented machinist, so I'm feeling pretty lucky. His shop is something to behold.

    Is 4043 is safe for repeated stress of the type it will be subjected to on a clutch lever mount?
  20. David R

    David R I been called a Nut Job..

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