1st oxy/acet aluminum project

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I picked up a lightweight oxy/acet torch and some supplies recently from TM Technolgies about a month ago.http://www.tinmantech.com/html/alumi...ing_system.phpI have been experimenting with welding aluminum in my spare time and decided to build a vacuum bleed tank for brake jobs. It seems very difficult to get the technique right as there are so many variables. It is a fluxed process that requires just the right flame in order to weld fast before oxidation sets in, but not too fast as to blow holes as I did in several places. In any case the I managed to seal the tank on the first try. The base metal was some scrap and I believe it is 3/32" 3003 and the filler is 1/16" 4043 tig rod. I used a #3 tip with 2.5lbs of acetylene and 5lbs of oxygen.  Comments are welcome.  Check it out...
Reply:Good job.  With practice your welds will clean up.   Id personally run 5lbs acetylene and 25 on the o2.  Otherwise looking good.  Great idea too IF it Catches...Let it Burn
Reply:looks good, welding on aluminum with a O/A torch is way hard.  I tried it some a while back and it was very frustrating to learn.  The flux rod i had to use was not cheap either.  Good luck with it.
Reply:I welded some aluminum, a few years back, with a similar set up. My welds looked like bird crap and the part did not stick together to well. I made them buy a tank of argon to tig weld it. The welder was just sitting there cause no one knew how to use it. Go figure. A few hours later, I had the few parts they needed, and much prettier.Anyway, those are very good welds. Practice, practice, practice.
Reply:ebaker Looks good, cool idea.  I have played with welding aluminum with o/a.  While I do like to weld mild steel with the torch, haven't done much aluminum.    How did you clean the flux off the box?  What is the secret to getting the welds like Tinman shows on his page?     Did you get any of the instructional stuff from Tinman? Have you tried the lenses they sell?
Reply:Thanks for the comments.  I was a little apprehensive posting in a welding forum but what better way to get constructive criticism.I used up a 40-cubic foot tank of oxygen just on coupons before I felt I had enough technique to be able to come close to beginning a project.  I know that welding aluminum is quite difficult in most processes, but keeping it clean is more then half of the welding with OAW.  Tack it... clean it... weld an edge... clean it some more... and so on.To get a solid fusion weld without inclusions is quite interesting.  For me it was all about keeping the surface free of oxidation, moving fast with the torch, and using plenty of flux. Getting the flux off is actually not that bad at all.  Just wait until the part cools to the point where a wet rag just steams on contact and rub away.  Then you just stainless steel wire brush the remainder.I do not know the secret just yet for getting welds like the Tinman shows on top of that page.  I would imagine the 25-years of experience he has in welding doesn't hurt.So far, it looks like the characteristic "stack-of-dimes" is more for cosmetic reasons with OAW.  When I get a good run going and the torch swirling just right, there is a very subtle dime look to it but not at all like you can achieve with TIG welding.I bought a complete aluminum welding kit from TM Technologies.  It came with the filter glass and it works extremely well.  The sodium flare is completely filtered out allowing a very good view of the puddle. It is a lot of fun but somewhat tedious and I know it will require lots and lots of practice to get proficient.Eric
Reply:Well Eric youre definately doing fine.  I never did much with the o/a torch on alum.  Ive done it with stick and tig.  Thats all the alum I gotta do to know its a pita.  The whole stack of dimes thing...i dont fuss with it.  I think its just one of them things somebody said they liked it.  and then it spread.  I admit it looks good.  But too many folks search for the stack of dimes look they miss what they are really trying to get.  Thats good fusion and proper penetration per joint specs.  It can look like crap as long as it holds you know.   Ive seen plenty of xrayed welds that looked like my 7 year old welded them and yet they passed...I admit quality is always to be desired...but somedays Im like the heck wiht quality just pass dammitt IF it Catches...Let it Burn
Reply:did you use a henrob torch? or a dillon if so thay weld at 4psi for both gasesChuckASME Pressure Vessel welder
Reply:It's actually a Meco Midget Torch.  I am not familiar with the others you mention.  It's all new to me.http://www.tinmantech.com/html/meco_midget_torch.php
Reply:oh you got the midget  ok well nvm im sorry ignore what I said youre right...thats a totally differnt rig.   Im thinking of a conventional torch.  Those things are a real trip.  Ive only heard of them in the past few weeks.  Sounds pretty handy for art work and small projects.  how do you like it so far? I know you dont have much to judge it by so perhaps I should ask you again in a month or twoIF it Catches...Let it Burn
Reply:thanks for the link that is a neet torchChuckASME Pressure Vessel welder
Reply:So far I like the lightweight setup.  I have not really had too much time on it yet, but the #3 tip has taken me up to 1/4" aluminum.   I also bought a #5 and #7 which is supposed to be large enough for 3/8".  It is very easy to manipulate when working and allows good control of the weld area.I'll be posting back with updates as my future projects move along.  Eric
Reply:Ebaker,I don't really know anything about OA on aluminum, just TIG, but that won't stop me from posting my 2 cents.I am sure OA of aluminum would be very difficult, and you absolutely did an amazing job.One thing I was taught about brazing with OA, that should apply equally to welding aluminum, is to use a slightly reducing flame, so as not to oxidize the base metal.As you may be aware, the "perfect" welding flame for steel is generally a neutral flame, where the O and A are balanced to produce a sharp blue flame.  When more oxygen is added the blue flame gets smaller, more constricted, and it is oxidizing to the base metal.  When less oxygen is added, the blue flame gets more diffuse and feathery, this is the reducing flame.The excess acetylene in the reducing flame prevents metal oxidation. The excess acetylene will tend to combine with and remove oxygen from the aluminum surface, and act as a shield gas to exclude oxygen from the air.  This should help in OA of aluminum.What do you think?
Reply:Thanks for the compliment, it always helps to hear that it doesn't look too bad.  I have been keeping the flame just on the rich side of neutral.  I have a nice dual cone flame but perhaps I could add a bit more acetylene and see how it goes.  I know when the regulator drifts as you can readily oxidize the surface with the flame when the acetylene flow drops.  It seems to build oxidation just from exposure to the atmosphere especially at high temperature so as you are preheating in front of the puddle, you just have to move quickly to reduce the oxide build up.I'm still very much learning as I go, so any advice helps.Thanks,Eric
Reply:Ever thought of doing any boat or trailer repair work?