Team Go Dog, Go! Modified Partial Streamliners

[wobblywalrus]

More pictures of cracks. 

[Peter Jack]

The propane torch allows you to apply the heat directly to the area you're about to weld and taking the time to shut off the torch and putting it a little away from the welding area gives the heat time to spread a little which never hurts. 4043 is much more malleable than 5356 so stands a much better chance of not cracking. Your camp stove probably doesn't get enough heat into the ramp and it scares the bejesus out of me to see that fuel tank sitting right below where you're welding. Before you ever start to weld take that thing outside the shop or at least well away from the welding. A much wider and deeper prep would really help the whole procedure. You should ideally push the weld right through although I know that can be a little hard to control. A good solid preheat is going to be your best friend.

Pete

[Stainless1]

Is there an aluminum scrapper in the area with a XRF tester... I watched the guy at the Yard here pull this big meter looking thing out of a case and sort out the types of aluminum a guy brought to the front to buy.  He only wanted 6061... but he had some 2024 in there....
If you are sure what aluminum you have then OK, but if you are not sure, one of those testers will tell you.  Hopefully you are not trying to weld a 2024 plate to your 6061 ramp.

[wobblywalrus]

The plates are an unknown type.  They were cut off ends from some project at a fab shop in West Salem.  The guys were tired of tripping over the stack of them.  They are 4 inches wide, 6 feet long, 1/4 inch thick, and I paid $10 for four of them.  The lap welds are working just great for some reason.  The project will be redesigned so it uses lap welds, only, for the unknown plate.

Our scrap guys basically know the metal is aluminum and not much more.  This is Oregon...

A torch will be used for pre-heat.  That tank looked safe to me, but I'm from Oregon...     

[wobblywalrus]

The local scrap guy told me about another scrap yard on the north end of town.  They do not have 8-inch channel, either.  The local metal supplier tells me I need to order 25 feet of channel or no channel.  So, it is time to figure out how to work with what I have.

The strongest and easiest to weld joints will be with 6000 series aluminum and 4000 series wire.  The scrap guy tells me to assume all plate is 5000 series unless it is stamped different and 6000 series plate is very scarce.  He showed me some 6000 series bar stock that is wide and flat.  He also said the 6000 stuff is marked with alloy designation and temper.  Several pieces of 6000 bar were bought for a reasonable price.

My welding settings are for the thickness of the metal and wire as based on the chart on the underside of the welder cover.  Evidently there are many different ways to weld the same joint with completely different settings and the guy that put the info on the chart does not know which one I am using.  Methods differ as to chamfering, welds on one or both sides, etc.  The weld method with the lowest amps and wire feed might be best if heat distortion is a problem.  Looking up the joint in a welding book and figuring out exactly what to do is recommended, as per chamfering, wire and gas feed, etc.  I was hoping this project would not be intellectual.  Maybe not.  Some thinking is needed.

The annealing was cleaned off before I welded.  The scrap guy said to clean all that off and oxidation too.  He said the weld area should be bright and shiny throughout.  He welds with MIG and a spool gun like I do.  He uses a "stack of dimes" method.  I do not know how to do this.  Maybe there is something helpful on U-tube.  Progress is being made.

 

[manta22]

WW, you can rivet or bolt together stuff without worrying about alloys....

Regards, Neil  Tucson, AZ

[wobblywalrus]

Nuts and bolts are my usual solution.  New skills are what I am trying to learn and there is no better victim for this than the loading ramp.  Heck, if there is a problem with it I can go to the lumber yard and get a 2x12 to replace it.  Some serious education is happening in the fab shed.  By the end of tomorrow morning I should be where I progressed to a couple of days ago. 

[manta22]

"By the end of tomorrow morning I should be where I progressed to a couple of days ago."

WW, we all know that feeling!  :-P 


Regards, Neil  Tucson, AZ

[salt27]

"By the end of tomorrow morning I should be where I progressed to a couple of days ago."

WW, we all know that feeling!  :-P 


Regards, Neil  Tucson, AZ

Around here we call that feeling, "optimism". 

[WOODY@DDLLC]

Progress in spite of our efforts is always encouraging! 

[wobblywalrus]

This is the first time I am making a large aluminum structure.  Jobs done before were little aluminum items.

The two plates are 1/4 inch thick suspected 5000 series and 3/16 inch thick 6061 T6.  Both edges were cut with a sawzall and there were some gaps between them, maybe 1/32 inch on average.  Both plates were locked in place by previous welds.  Some I-net and book reading says the parts expanded toward each other when heated during the weld and then contracted back into place after cooling.  The strain of the contraction cracked the weld.  The solution is to have no gap between the parts before welding.  Is my thinking correct?

There was some localized distortion at the welds.  Heat was applied to relax the joints and force was used at the same time to straighten the areas.  This was something I did as an apprentice machinist.  It brought back memories.

The ramp as a whole had some distortion.  It was set on blocks in the cellar.  A datsun jack, post, and the big beam that holds up the house completed the setup.  The ramp was straightened.  Then, a big Harley Davidson Electra Glide size downward force was applied to the center of the ramp.  A weld snapped.   

[Peter Jack]

You need a generous prep and good preheat. It's difficult to get penetration in aluminum. When I'm welding up a tank I weld with a keyhole at the point of the weld to ensure penetration. Don't overthink the process.

Pete

[wobblywalrus]

The welds that held all showed some small linear lump in the metal on the opposite side of the weld.  Sorta like the mound left in a lawn after a gopher digs its long hole under the surface.  The weld that broke showed none of this.  It was ground out and there was not enough penetration.  It was redone.

There are four cross members between the rails.  The load test was done with them to see if there were big problems with material compatibility.  Only four cross members meant they would be streamed hard and problems would show up.  They are suspected 5000 series plate pieces welded against the 6061 webs with ER4043 or ER 5356 wires.  All welds held if they had adequate penetration.

The finished ramp will have three more cross members.  They are added using 3/16 bar stock against 3/16 channel web.  All are 6061 T6 and welded with ER 4043 wire.  This combination is much easier to weld.  What I am learning is to design the project using similar alloys and metal thicknesses as much as possible.  This makes fabrication easier.  The weld shown uses ER 4043 and the 6061 alloys.

What does a key hole look like?

[Stainless1]

Like an old fashion key hole.... circular top, slot bottom.... Can't say I've seen on using MIG, but I don't MIG that much. 
See it all the time with TIG... tells you it is time to fill and move 

[Peter Jack]

Good description Stainless. I do as little mig as possible on aluminum and to be honest I don't use a keyhole intentionally. I just pour the weld as hard as I can into a good prep with generous preheat. The penetration on the backside isn't always pretty but it means you have good penetration. Practice with good manipulation definitely helps.  

Pete