Another weld critique plz.

[moored4]

Anyway,.... a buddy is modifying/adding a new leg lift system of his design for his aluminum boat lift ........ I gave it a shot but where failure of the welds could lead to potential property damage I want to run a couple photos of the welds past you guys for your thoughts. Do these welds look ok or are they destined to fail?

Each leg is about 4.5 feet tall and each of the four spacers welded to them are about 12" tall, the aluminum is 3/16" thick and welded with a Lincoln 180 on highest setting D and wire speed at around 430ipm. I decided to do the stop start method of welding as I found it easier to maintain a relatively straight run when compared to maintaining one continuously steady movement.

Thanks.

I do not understand where this leg goes are what it will be used for, maybe in a boat house to get a boat out of the water for storage, but with the start stop method I would question the penetration of the weld.

.

 

[Jaylegger]

I do not understand where this leg goes are what it will be used for, maybe in a boat house to get a boat out of the water for storage, but with the start stop method I would question the penetration of the weld.

.

I probably used the incorrect term, the start/stop wasn't referring to triggering, but a pausing then move forward, pause and so forth motion of the gun. The boat lift is a free standing device which you drive a boat on then raise it out of the water. something like this: The new legs are being added to accommodate a cranking system for leveling the lift.

 

[Shield Arc]

I probably used the incorrect term, the start/stop wasn't referring to triggering, but a pausing then move forward, pause and so forth motion of the gun.

Glad you posted this, I read your thread earlier this morning, but I didn't have time to reply. Here is what I just typed for you.

I've never done much aluminum Mig, haven't touched my Cobramatic in about three years. But I sure wouldn't use the "start stop" method! Years ago I worked with the best weldor I've ever seen. He got handed a job where he had to weld 10-GA to 3/4 inch think mild steel. He used the "start stop" method with Mig. This project was to be DPI, I never seen so much blood in my life. He had to cut it all apart and start over!

Dye penetrant inspection - Wikipedia, the free encyclopedia

 

[Jaylegger]

Glad you posted this, I read your thread earlier this morning, but I didn't have time to reply. Here is what I just typed for you.

I've never done much aluminum Mig, haven't touched my Cobramatic in about three years. But I sure wouldn't use the "start stop" method! Years ago I worked with the best weldor I've ever seen. He got handed a job where he had to weld 10-GA to 3/4 inch think mild steel. He used the "start stop" method with Mig. This project was to be DPI, I never seen so much blood in my life. He had to cut it all apart and start over!

Dye penetrant inspection - Wikipedia, the free encyclopedia

I was having difficult getting sufficient penetration with cold edges when welding inside corners using a straight continuous bead so to the internet I went and found this:Mig Welding Aluminum with a Spool Gun scroll half way down page. After trying out the step and pause technique I found I had better control of the weld and overall it provided better penetration with better edges so I went with it. I assume the guy at welding tips and tricks has done a little aluminum welding so felt comfortable using the "step and pause" technique for this application.

Perhaps my trust was ill placed?

 

[Shield Arc]

What you're doing is what I call a whip. I don't necessarily whip everything, but I do move everything I weld except Tig. 7018, Mig, wirefeed I move the puddle to a small degree. 6010, 6011 I whip. Here again what little aluminum Mig I have done I whip it too.

This was done when I first got my Cobramatic, my power source doesn't have a hot start, as you can see the weld starts out cold, but then it gets going.:laughing:

 

[Jaylegger]

So to sum up your point which seems a little contradictory, iyo is the stop/start aka your whip outlined in the attached link suitable? Comparing my welds to the one in the link they look of similar quality on the surface anyway with no obvious cold edges though the weld depicted in the link is more consistent with less splatter. Your weld also looks similar to both mine and the links weld except for your cold edges. So are you saying your stop/start aka. step/pause aka. your "whip" weld is not suitable for joining to pieces of aluminum together?

 

[Shield Arc]

So are you saying your stop/start aka. step/pause aka. your "whip" weld is not suitable for joining to pieces of aluminum together?

Oh I think it's fine, doesn't really matter which method is used.
What I have a problem with is the "pop pop" method! A series of tack welds. Where the trigger is pulled for a split second, then let the puddle cool, and pull the trigger again, repeat as many times as necessary. Those cold starts will bite you in the butt. That was the reason I posted the story about the DPI testing. When you made the statement you did the "start stop" method, I thought that is what you were taking about, the "pop pop" method. When whipping, the puddle doesn't really have that much time to get too cold. X-ray pipe is welded everyday with the whip method.

 

[Jaylegger]

Oh I think it's fine, doesn't really matter which method is used.
What I have a problem with is the "pop pop" method! A series of tack welds. Where the trigger is pulled for a split second, then let the puddle cool, and pull the trigger again, repeat as many times as necessary. Those cold starts will bite you in the butt. That was the reason I posted the story about the DPI testing. When you made the statement you did the "start stop" method, I thought that is what you were taking about, the "pop pop" method. When whipping, the puddle doesn't really have that much time to get too cold. X-ray pipe is welded everyday with the whip method.

I get it now thanks, I at first thought the dpi story was using the whip aka my stop/start method. Perhaps the method should be called the "walker" method, pretty much self explainable.

 

[Chilly807]

Aluminum sheds heat so well you may be better using a long run, but if you're having trouble staying on course that's a problem too. Personally speaking, if you have a 12 inch weld to make, you may be better doing it in three 4 inch sections with a skipped area between the welds. Most jobs don't require 100% weld for strength, but it does look better.

I've never tried welding aluminum vertical, it'd take me some practice to decide which way was better for me. Usually down works better than up as far as puddle movement goes, but don't quote me on that.

You're pushing the gun, I assume? Better penetration and gas coverage when pushing, especially with aluminum.

I've got the basic Miller Spoolmate 100 gun that came with my 180 Millermatic, I've tried both 5356 and 4043 wire through it with good results.

Sean

 

[crazyal]

Glad you posted this, I read your thread earlier this morning, but I didn't have time to reply. Here is what I just typed for you.

I've never done much aluminum Mig, haven't touched my Cobramatic in about three years. But I sure wouldn't use the "start stop" method! Years ago I worked with the best weldor I've ever seen. He got handed a job where he had to weld 10-GA to 3/4 inch think mild steel. He used the "start stop" method with Mig. This project was to be DPI, I never seen so much blood in my life. He had to cut it all apart and start over!

Dye penetrant inspection - Wikipedia, the free encyclopedia

Who did the testing? I've seen lots of plants who have people who read the can and think they know how to do the testing. I once worked at a company that made the high speed Amtrak train and watched a guy test one of the couplers. Needless to say when an untrained person decides he's going to test something in front of a level 3 inspector who also had to sign off in front of an government rep it didn't go well.