3/8th Aluminum with my PM205

[Robert s]

Making some steady progress. Finding it interesting to clamp this thing up. I am a hobby welder and this may be a bit out of my comfort zone in dealing with good penatration and controlling distortion. I have certainly got an array of jigs and what not to hold this thing together.

I know what you mean about the clamping up, sometimes I just pray that I get the thing tacked up before anyone sees the spectacle. I have often thought of employing and training an octopus, for just such tasks.

[trackmaster]

Hi www, reading your post I'm not sure of your desired outcome in this respect: You mention not welding thru to the "finished side" of the project. So you are welding from the back side? In that case you do not want to penetrate completely? If that is the case then you you do not need 100% penetration, right. So you would only need to consider the structural requirements of the part itself, ie is the weld strong enough to support the parts. It may be that a shallow partial penetration weld is sufficient for what you have on hand. To be sure making a full penetratating weld on 3/8 aluminum is a little beyond your machine in a daily job sense, but you can get er done.

If you feel your single pass is not structuraly sufficient, then yes bevel a bit more, pre -heat is your friend. Dont worry about pulsing. The frosting is etching or "cleaning" so you need LESS not more. Wide etching is indicative of electrode positive, or a wide shallow bead profile (more heat in the electrode). A/C freq is fine around 60-100.
With pre-heated metal then quickly stainless brushed, lay down a root pass. You seemed to indicate some kind of "moving quickly to the center, and then to the sides", ..... ??? not sure if your thinking weaving or walking or something, but if your looking for deep penetratating pass don't move the the tungsten back and forth, travel in the direction of the seam only. No stick or mig circles etc. here. You can only make a weld bead so wide, so if you are not filling the valley, so to speak then you need a filler pass (many different names). This is where you can get fancy and weave a bit to spread the bead.

So unless this Cupola has to be very strong and or support a lot, you may be making it more difficult than it needs to be. Also sequence your welds to control distortion, sometimes large flat parts like that just need to be "coaxed" back to flatness after welding with some muscle! lol ! Sorry for the late post on this thread

[www]

Thank you Trackmaster.............good points. I will post some pics of the next stage of the design and fabrication as it gets completed. I think this new addition to the design of my mounting brackets will reinforce what I was worried about with the front part of the panels not getting a weld on its side. Hard to explain but the pics will explain further. I am no longer worried about the penetration. The grounding to the work helps and design issues will also get me to where I want to be for strength.

My feeling on the wide etching is if things are not hot enough during the weld this look will be more pronounced and that is what I was trying to get a confirmation on.

[everlastsupport]

Making some steady progress. Finding it interesting to clamp this thing up. I am a hobby welder and this may be a bit out of my comfort zone in dealing with good penatration and controlling distortion. I have certainly got an array of jigs and what not to hold this thing together.

That does not look like an easy one, and I can relate for sure.

For me that would be a hold it in place, look real good and hard at alignment, tack real light, adjust (most likely required), and weld it in. I think Robert might have said that in a different way. haha.

[www]

Mike would you have any tips for tacking aluminum while holding the work with one hand. I guess where I would be a bit stumped on something like this is without being able to add rod? I guess there is an ideal method for this so you don't just put holes in the work. The next post I make will show progress of what I need to do today on the project and its a 2" x 3/16" plate rim onto the top edge of the 3/8" main frame. It will need to be angled up and holding and tacking would come in handy. As I am not comfortable with the tacking with out using rod I will be making up some sort of a clamping jig I guess so I will post some pics later on if things go good.

[sportbike]

You can tack without the rod, just be sure you weld overt op of the tack with the filler. An autogeneous weld (weld with just the base metal) can be done on many materials, but with aluminum, especially 6061, the weld will crack if it is not diluted with an appropriate filler alloy. That said, it will not hurt to tack it without filler, and then weld over it with filler.

With the thickness of the parts you are working with, you will probably be best suited to make a few very small tacks without filler, then go back over and make the tacks larger with filler, then go over with the actual weld.

John

[performance]

WWW,
There are some nice assistants that you can buy. Bessey is a good company that has many adjustable clamps and jigs that help in hold about anything. Strong hand tools, is another. They first came into the market with knock Bessey clamps, but they have rapidly advanced into about any type holder, and clamp imaginable. If you need something held, you can do it with one of these "assistants". Not cheap but beats hiring someone to come in and hold it for you.

[everlastsupport]

Mike would you have any tips for tacking aluminum while holding the work with one hand. I guess where I would be a bit stumped on something like this is without being able to add rod? I guess there is an ideal method for this so you don't just put holes in the work. The next post I make will show progress of what I need to do today on the project and its a 2" x 3/16" plate rim onto the top edge of the 3/8" main frame. It will need to be angled up and holding and tacking would come in handy. As I am not comfortable with the tacking with out using rod I will be making up some sort of a clamping jig I guess so I will post some pics later on if things go good.

See Sportbike's post #26. You do not need filler to tack with the TIG, you can melt the 2 piece together. Go light in case you have to move it.

[jakeru]

IME, autogenous welding on 6061 aluminum, including tack welding without filler rod, will give a really crack-sensitive weld. It only takes a small dab of filler to make a strong tack, but you'll need both hands free to do this.

It sounds like you could use a "third hand" (AKA "welder's finger") to hold your parts still for two handed (TIG+filler rod) tack welding. They are a huge time saver for jigging up small parts; see attached pic.

[eide]

Cool project, good luck! I really don't like "reverse" bend parts for the post weld shape because it's so hit and miss. But, when I have a multiple run I will usually weld the first one up and see how much it moved, then adjust the others accordingly. There's always a little bending and pounding, but this limits the majority of it to the first piece.

[www]

The pictures shown here are what I was trying to explain for beefing up the design flaws with no weld on the face of the unit. This transition area will also act as an anchor for bolting the roof of the cupola to the frame of cupola. It is the same angle as the roof line of the cupola.