Drunken dirt dauber??

[Protraxrptr17]

Here's some pictures of an old busted up swingarm off my race bike that I daubed at this evening. Tell me all my faults and mistakes.

Here's my setup;
300DX TIGRunner of course
180 amps
started with 70% balance and ended up with 85%
1.2 pps
50% peak
30% background
10 second postflow
3/32 1.5 lanthanated
tried a gas lens and diffuser on the last picture (didn't see much difference)
1/8 4043 filler
25 and later on 30 cfh
100% argon

This swingarm was busted on both sides, so there are two different welds and prep pics

First prep pic

[Protraxrptr17]

First weld pic

[Protraxrptr17]

Second prep pic

[Protraxrptr17]

I brushed all that black stuff off and ground out one of the legs of the bead and rewelded it because it looked real bad on this weld. That's why there is no soot around it. Why is it doing that? This is the first time I've had this happen. Most of the time they are pretty shiny.

[jeffscarstrucks]

Hi, I have fixed some cracks on my son's Suzuki quad swing arm in the same fashion. I think the black is some oxidation showing up after the cleaned metal is welded and then possibly unshielded because of the wide gap left to fill after prep is completed. How long between prep work and welding? It seems like when I prep with a course brush or wheel the material will reoxidize pretty quickly. Maybe the wide gap is allowing outside air to reach the puddle before the torch is moved allowing the contamination. I'll be interested in what others have to say. Good Luck, JEFF

[Andy249]

Could be a variety of reasons why the weld isn't as clean as what it could be...

Is that part of the swingarm sealed? My guess is that the air inside could be expanding as it gets heated up and ends up being pushed out past your weld letting a little oxidisation occur. Also being a swingarm there might also be dirt and impurities that have worked their way in there and are being burnt out when you weld causing contamination as well.... just a couple of ideas. I usually see this sort of thing when I weld up cracks on outboard motor legs and hull cracks in ally boats, it can be a real pain and sometimes it takes a few goes to get a good weld on it!

Let us know how you go!

[dyn88]

why didnt you stop drill the cracks? the air in the unit expanded like andy said. drill a small hole awaay from the weld area to allow air to escape.

[HAWK]

Tinning the area to be welded may also help if the material won't come clean. Tinning: prep the area as you originally did, weld it slowly concentrating on complete penetration. Grind the weld bead slightly concave to the swing arc surface and check for porosity. If done correctly there won't be any. Now clean this new ground surface and reweld. It should come out beautiful: Nice, clean, good color match. Sometimes you have to plant a good base to weld on to.

[Protraxrptr17]

I didn't drill holes because the tubes aren't totally sealed up. There are holes already in it for brake line brackets and such. This swingarm is just a scrap. I won't be riding on it, I was just using it for practice.

Andy,
Yeah it was probably full of dirt and junk. I raced on it several times with the cracks.

Do I need a backing dam for this type of work? How do they hook up?

Hawk,
I'm going to try that. How do I check for porosity?

What about the other properties of the welds? I think I'm getting good penetration. I'm not very good at controlling the amperage with my foot control. I usually back off too fast and my puddle freezes. That's why the bead isn't a consistent width.

What about machine setup? Am I close? Any suggestions on setting changes? I forgot to put my frequency setting in the first post. I started with 90hz and later increased to 120hz. Seems like I can do better with lower settings. Don't know why.

Thanks for posting fellers!

[Andy249]

I have found that sometimes the holes are just handy in terms of having a good starting place in good parent metal, it is actually interesting to see the way the cracks have travelled. Although I am pretty sure the swingarm would be cast, it seems to have followed along a line where I think you would place welds to make that shape... just a thought though.

By backing dam do you mean backing bar or strip? You could try that although in this senario it would be quite difficult to get one in there in the first place. Backing bars are generally used where you might want to control root penetration or in areas where you want to align the two pieces you are welding together, such as in pipework.

If the swingarm is cast, then it is quite possible that the filler rod isn't the perfect type for the job, with cast you never know what alloy was used, and in my experience even the alloy can vary from batch to batch. I think in this instance referring to the procedure that Hawk suggested would be the best way to go.

When it comes to weld prep my personal preference is to use an aluminium cutting blade (looks like a saw blade with tungsten carbide teeth) instead of the abrasive cutting discs as they are a lot cleaner with their cut and are far less likely to leave impurities in the joint. Some aluminium cutting and grinding discs use the binding agent to keep the wheel clear from clogging, there is nothing to stop this and other impurities from entering the weld prep area and making life difficult when it comes to welding! You can tell if you weld has porosity by cutting (preferable) or grinding into the weld and keeping an eye out for little spots, they should be relatively easy to see in contrast to the shiny, freshly cut ally around it.

Hope you enjoyed the novel!

[HAWK]

Porosity: When you grind the bead down flush or slightly concave there should be no visible pinholes to the eye or a 10X magnifier. Settings: 110HZ, 72%EN balance, pulse off, sequence off, 25 cfh sounds fine. Try keeping your foot pedal more consistent. The amperage is seems hot enough. Let up on your pedal some as the material gets warmer. You may also have to increase your travel speed as the material heats up. You want enough heat for a good puddle to start and then keep the filler melting into your base. You can always set it high and adjust it with your foor pedal. It looks like your torch is leaning too far back toward the weld. Try a 15-25 degree tilt off the vertical with the back cap leaning back toward the weld beginning. This could be part of your black soot problem due to inadequate gas coverage. HOPE THIS HELPS.

[HAWK]

Protraxrptr17,

If you are referring to an inert gas backing dam, then no it is not necessary in this case. If the swing arm was SS, then an argon purge would be helpful. There are numerous and expensive ways to build a backing dam. If the work is not absolutely critical, then stuffing the open ends with rags will give a decent seal and tuck the argon flow hose inside the structure through one of the ragged filled openings. As long as gas flow is sufficient little atmospheric contamination will hinder your weld.

[Protraxrptr17]

Andy,
Very observant of you. The swingarm tubes aren't cast, and yes these cracks formed along the cuts that were made in the tubes to narrow them down to the pivot tube joint. They welded these cuts with some sort of wire machine it looks like. I ground out the old welds with an abrasive grinding disc on an angle grinder and cut down in the cracks with an abrasive cutting wheel on my Dremel. Sounds like you nailed my contamination problem. Where do I get some of those cutters you're speaking of? I assume they go in a die grinder?

Hawk,
Glad to hear the gas backing dam isn't really necessary. Seems like that would be alot of trouble. Is using the pulse to help with my rhythm bad for weld integrity?
Should frequency settings change with material thickness or only on the shape of bead I want?
You're probably right about my torch angle. I have to really watch myself on that. I have a habit of leaning it back so I can see instead of getting my head down there.

BTW, make as long a post as you like. It is very important that I learn to make perfect welds and I hang on every word of advice I can get out of anybody. I read this forum every chance I get and read through old threads when there's nothing new. You have no idea how much I appreciate the help ya'll give. My dream job depends on my ability to master this process. I was offered a job at one of the top ATV race shops in the country. They build engines, exhaust systems, and sponsor alot of the top pros. Word is that next year they are stepping up their program and supporting more riders and adding some new product lines. They say that good welders are in high demand and I'm almost guaranteed a spot on the team if I can learn this. So I'll be needing lots of help from ya'll because I don't have anybody around here to talk to about it. Thanks a million,
Zeb Beard

[Andy249]

I use Nicholson Aluminium cutting blades which I just put on my 4" angle grinder the same way you would a grinding blade, be VERY careful with this setup though, if the blade jams it can run away from you (been there done this a few times, usually happens when one is in a hurry!). I have managed to find these blades in our tradetools shops so I would imagine it would be the same over there. I also run the bigger versions in my circular saws for cutting aluminium sheet and plate. A bit of lubricant usually comes in handy for long cuts.

When it comes to pulse frequency, the way I understand it, it is to help customise the welder to you. Pulse frequency influences the number of dabs of filler rod you add in a period of time and also affects the speed at which you travel. What I would do is set your machine at the extremes and experiment, that is the way the rep showed me how and it is a really graphic way of trying to understand the different settings and what they do!

I've just bought myself a sort of blue (CigWeld) machine, I couldn't wait for the time for a blue machine to come out of the states and to say these new inverter based machines are awesome is an understatement compared to the older solid state gear! The torch that I am using has a flexineck so it adapts to my arm angles and so on, I am feeling very spoilt at the moment for sure!

I know there are a few of us on the forum who keep harping on about this, but the best way to learn is through a college or learning institution, here in Australia we pay a $100 to do a 10 week course (1 module) on a particular process in various positions and on various materials, best bit is, you take notes and take home your work book at the end of it all and constantly refer back to it as you take on various work. To my way of thinking this is an excellent investment in the future!!

By all means, try all of the advice that is offered to you and work out what works for you. The way welds are tested for integrity is fairly standard across the board, but everyone has their own knacks that help them get there. Perfect practice makes perfect!

[Andy249]

I thought I might post a pic of the nasty, nasty tool I use for docking pieces of aluminium and making aluminium things fit. It looks pretty nasty in my opinion and believe me it is! I wear my leather welding gloves when using this jigger as I reckon it would make short work of things like fingers and tendons! Can't wait till I get my compressor and air angle grinder, these are generally a fair bit nicer to use, dangerous none the less!