Announcement

Collapse
No announcement yet.

Bubble gum, cracks & holes....s

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • cliffrod
    replied
    Thanks for the additional copied info, Charlie. I'll add it to my cheat sheets. I had seen that before but not copied it & couldn't find the thread. I have been doing the alcohol in flux. I keep a stainless toothbrush specifically for aluminum welding and nothing else. Just got a new one because I couldn't find the one I had. Grrrrr..

    Might be able to video the welding, but things happen in a very solitary world in my shops. Hard to get any video of me cutting stone without an appointment. Rarely ever have anyone here except when I'm really behind schedule and don't have time to deal with anyone. No spare lens either, so doubt it would film very well.

    I did get some thicker pieces of scrap aluminum (5000 series) for TIG practice. I bought my Gairu from a race seat fabricator. One of his top guys who tigs full time gave me a quick TIG lesson, said it looked like I was doing well & then sent scrap home for me to practice with. Just haven't had seat time for that yet, either. I have carefully watched Peter and Jim gas welding at Will's & tried to listen to what they said, so have that in my mind as how the real Masters that I trust completely do it. Never have bought any DVDs yet. Probably should..

    Today's plans to finally weld a dolly/cart for my Gairu today so I can get it inside turned into an entire afternoon of being electrician next door at my mother's house.. Maybe another day.

    Leave a comment:


  • Chazza
    replied
    Cliffie is it possible to get someone to film you, whilst you are welding? We might pick up some things that can be done to help your technique.

    if you ask Peter, he can direct you to his DVD on welding aluminium; which made me realise that the technique is not greatly different to welding steel.

    In case anyone missed these pearls-of-wisdom from real experts on the web I post them below:

    "For aluminium (16 gauge) I would highly recommend trying either a no5 or no7 BOC style (UK) welding nozzle and, most importantly, turn the gas pressure down to 2-3 psi max (13 -20 kpa). You want a soft, fat flame. A lot of beginners make the mistake of running a too narrow flame cone, with higher than necessary flame pressure, which inputs too much heat into a thin weld zone causing burn through. Also, you have to weld aluminium at a very quick pace with oxy-acetylene. We are talking almost feet per minute as opposed to inches per minute a la steel. This is where the true art to gas welding ali comes in to form. Fast, fast, faster!

    I seldom add rod to the puddle on ali body panels - for me the rod is there literally to start the weld then finish the last 1/4" of weld.

    Also, I was taught to oscillate the torch in continuous circles to the width of approximately 1/4" - 3/8" around the weld zone as you move the torch along its path. This, apparently, was the norm during WW2 era to decrease the intensity of the heat affected zone according to my mentor. It is said to even out the h.a.z. a little, which reduces stress. This method, with good practice, should produce a lovely, flat bead with perfect penetration: A weld that needs no filing and only planishing or wheeling to make the weld virtually disappear.

    Don't get me wrong, there are many ways of gas welding aluminium, but this is what I was taught and I find it works fantastically well.

    On a side note... and this is one that's sure to raise eyebrows: I only flux the edges of the metal and not the full width of the weld bead. I find there is more than enough flux on just the edges to facilitate a perfect weld. The advantage is that flux glare is massively reduced and you have a more even temperature distribution. Again, a nugget that was passed down to me during my apprenticeship in the 1980's. "

    Regards, Matt

    "sorry for my bad english.
    recommendation from me, always clean workpieces with alcohol.
    grease on the material leads to errors.
    next Step.
    important, always clean with a stainless steel wire brush to remove the oxide. No ordinary steel brush.
    always remove oxide at short intervals.
    new oxide layer in a short time again.
    no wind or drafts during welding.
    mix flux powder with alcohol and not with water.
    you will soon see great success and aluminum with flame welding no problem.
    fact is, gas welding is the best for alloy. for my taste and experience is tig not good for thin sheet. with tig is all time cracks next to the welding lines. i have learned alu welding in england and italy to the best specialists.
    how is the same as with doctors.
    questions 10 doctors and you get 10 different advice"


    Bernhard



    Cheers Charlie

    Leave a comment:


  • Rex_A_Lott
    replied
    What you're trying to do is difficult, even for somebody with much more experience than you, if that makes you feel any better. If you could get you something a little thicker and bigger to practice your technique, and then step down to the the small thin stuff I believe you would progress faster. The other guys cover it pretty well, start with a bead on flat metal and then move up to a lap weld and then try the butt welds. The only thing I might add, as Bill alluded to, go buy yourself a good stainless steel brush from the welding store and never use it on anything except aluminum you have already cleaned.
    I had the good fortune of being close enough to Kent White at Will's to see exactly what he was doing . It was remarkable how fast he was able to move and control the heat on those tiny little coupons! Its going to take you a bunch of practice to get that good. Good Luck

    Leave a comment:


  • cliffrod
    replied
    The temp issue seems to be a big part of my failures, Charlie.

    When i I get a good puddle, seems like there ends up being so much heat soak that I weld maybe an inch & then have the metal beyond the pool collapse to leave a 1/2" or larger hole. Tried flicking the torch to avoid the apparent excessive preheating beyond the puddle. Tried going faster and seem to lose my puddle. Going the recommended 2"-3" before pausing about would be nice. I'm keeping my pressures each regulated to the same either 3lbs or 4lbs (setting regulators with an external pressure gauge, not just the dials on regulators) and adjusting flame hotter & cooler. Seems viable to adjust the torch as needed to get things a little hotter or cooler, but no sweet spot yet. Same with different tips and even torches, which simply means that I am the common denominator....

    I am am not deliberately melting rod above the pool. Some of the blobs are trying to rebuild those holes, which is a very untechical the way I do it. The others blobs often happen when I try to control the temp, when I think I see a sag happening, etc. hit the molten material with a rod. If the rod is too cool, it chills the puddle & quickly stacks up. Then I melt off the rod and try to go beyond. Trying to heat a big glob to make it flatten or go away isn't the solution.

    I'm listening and anxious to do more as soon as there's time.

    Leave a comment:


  • Chazza
    replied
    Not that I have ever welded aluminium, but looking at your welds Cliffie, it seems to me that you need more heat.

    Wherever there is a blob, means that you melted the rod with the flame rather than melting it in the weld-pool.

    If the back of the weld shows the cut edges, then the weld pool was not big enough to penetrate.

    So this can be cause by a multitude of things, so firstly I endorse all of the excellent recommendations made by Skintkarter and add these suggestions;
    1. Try running a puddle without filler rod on your coupon. This is a good time to confirm tip size; size of the flame; torch angle, speed of travel, etc. Keep notes.
    2. If the puddle is good it will show on the back.
    3. When that is mastered, do the same thing using a filler rod; remembering that the rod is ALWAYS melted in the puddle never with the flame.
    4. And then when you are happy with the appearance of the weld, try doing a butt joint, bearing in mind that you will need to travel faster to stop the puddle collapsing.

    On the subject of welding small pieces, wet rags paced each side of the joint work remarkably well in controlling distortion on steel, and I can't think why it would not work on aluminium,

    Cheers Charlie

    Leave a comment:


  • cliffrod
    replied
    Any input you offer is welcomed, Richard. I'm focusing upon smaller pieces simply because that seems where I'll be working, especially in aluminum. A full fairing is part of this Guzzi project, but is a low priority at this point. 1-2 fairings like that and some sculpture concepts are the only "large" things I have in mind to do at some point.

    Leave a comment:


  • skintkarter
    replied
    Thanks Bill - I do use the drill technique on 0.9mm steel mig wire for my tiny tig ferrous welds. Works well. Kind of stepped back from the ali mig wire as I could only seem to get 5356 or 1100 and at some stage I want to do another bike tank, but with a polished finish. Gone back to the tig to keep the BMW project moving along, but shearing 5005 for filler. With a vigorous preheat, welds so far have gone pretty well and have held up to planishing flat.

    Cliff, sorry but I don't have much experience with small parts yet so can't really add anything constructive.

    Leave a comment:


  • Bill Tromblay
    commented on 's reply
    Hi, To solve the unruly wire, cut off the length you want and it can be straighten. Chuck one end of the wire in a drill and put the other end in a vice. Run the drill for mutiple seconds and it will be laser straight. The dab technique leads to a nice looking weld, hard to do with a curled wire 😊

  • cliffrod
    replied
    Thanks for the input, Bill & Richard. I understand the heat sink & related benefit when a larger coupon. How does this translate to an actual job piece that isn't large or ideally centered? Do you clamp it to a larger piece or pieces to provide mass for heat sink?

    On the coupons in my pictures and others not pictured, I should have mentioned that the first weld was deliberately produced in the center of the coupon. Probably that's why that weld tends to be better. I do want to be able to manage a less-than-ideal welding need. The difficulty welding with the narrow piece is very clear to me, both before & during the task, but it's a deliberate task.

    I'll plan to limit some of the variables and keep practicing.

    Leave a comment:


  • skintkarter
    replied
    Yup, as Bill observes, coupon size. I was doing 1 weld in the middle of a 300mm wide piece of scrap (a duff centre panel for my chin air dam on the Group 5) which was probably 500mm long at the start. I sheared off a 100mm piece, clamped the big bit to the bench and welded the small bit back onto it. Then sheared it off 25mm north of the weld for the next practice part. Thus there was generally a fairly realistic heat sink. On those bits you picture, you would struggle with tig. I'm shearing all of my rods now from the edge of the sheet and all I have in the shop is 5005. Particularly when starting out EVERYTHING needs to be a known quantity in my humble opinion. I even started writing down my fluxing techniques, tip size etc... as it's really easy to bamboozle yourself. Would suggest not welding on scrap you don't know the grade of. Too many variables. Just change one thing at a time if you are experimenting. The other thing which helped was making sure the sheared filler rod was not just a 12" piece (hence the pinholes from too many starts and stops). Making sure the rod was a full 36-48" helped me. I've bought some of Kent's mig wire and made a feeder, but couldn't get my head around wrestling with the resulting helix of unruly wire.
    Last edited by skintkarter; 09-23-2019, 08:41 AM.

    Leave a comment:


  • Bill Tromblay
    replied
    Hi,

    One thing to consider is the coupon size. Your test pieces are small and you would get different results with a 12" x 12" (300mm x 300mm) coupon. Heat distribution is very important, for a small panel you need to pull the heat away very often, like you are doing. You are getting there.

    Bill

    Leave a comment:


  • cliffrod
    replied
    Man, Richard- if my welds looked like that I probably wouldn't have started this thread..

    Seriosuly, my weld lately are far more challenged. A Meco rig is on the list, but not in the budget right now. I've got a few old torches but am limited on tip sizes here. The smallest tip for favorite old Airco Concoa is a 3. It seems to go ok but is probably too much. I can weld an inch, maybe two ok (not great) and then the area beyond the weld puddle usually drops through. Seems like too much heat soak?. Tried flicking, no good. The only thing that seems to help is to completely stop, wait for metal to cool and then resume welding. Problem is the more I weld, the longer I have to wait each time. Didn't try a wet rag to cool things faster, might have to.

    So I changed to my more clunky Purox 300,because I have size 2 and 6 tips for it. It seems more tractable, especially the 6. The 2 just wouldn't produce a puddle. Larger diameter filler rod or trimmed parent metal seemed to make it easier to manage to puddle & to pull out heat to prevent a hole. Ive got regular TIG rod and some rod from Kent that's half the diameter. The little stuff just disappears,,at least with the equipment & techniques I'm using.

    See pics- Of these 7 welds done this afternoon, the best looking one was (of course) the first weld.... Center weld on right side with big burn hole at end.

    I understand the issues with weld height, excess filler, profile of weld bead. Just having trouble consistently producing a nice looking penetration sing athe on the back. Even when the top looks great, there is usually a line visible on the back- cut edges of metal not fully incorporated into the weld puddle. Maybe that has more to do with panel/seam alignment?

    of these 7 welds done this afternoon, the best looking back side was (of course) the first weld..

    Ii can say I have no idea what this aluminum is. Maybe that's part of the problem. I've welded known 3003-some, not a lot- and it didn't seem this tough to produce a consistent result. This aluminum takes regular TIG aluminum filler rod as well parent metal rod.

    The interior welds obviously benefit from more equal heat sink during welding. I do want to learn to weld as needed, not just in ideal situations on a bench. That's one reason I welded the seat hump. I have to be able to do it when it counts, using real parts. Welding my gas tank well is the big prize. I would rather not make 6 of them in order to make one good one.

    Leave a comment:


  • skintkarter
    replied
    Hi Cliff. Must admit I haven't done enough practice - did buy Kent's DVD and a whole lot of gear from him, but need more seat time.

    I actually found that a larger tip worked better for me.

    Now of course everything is different in New Zealand and our tips in no way correlate to US sizings - in fact my NZ sizings in no way correlate with today's NZ sizings. Back in the 70' and 80's here it was really simple, you bought an NZIG tiny torch (Comet Junior I think) and it came with #6, #8, #10, #12 and #15 tips. You used #6 for fuse welding 20swg (1.0mm) CRS and #8 for 18 or 16swg CRS. The #15 tip was more for brazing and pre-heating. No of course it's all different, no doubt due to the EU and the fact that you can't buy a pork chop anymore with a small piece of kidney attached to the eye...

    When I started learning how to fail at O/A ali a few months back, I started with the #6 tip, fearful that anything bigger would instantly result in me having molten aluminium dropping onto my jandals (thongs in US speak - note not thong...). Well the #6 was bloody useless, even with the modest coupon size I was practicing with. Sure I could melt the filler rod, but it just sat on top in a big blobby mess. The #8 tip was better, the #10 better still and in fact I had my best results I think with the #12. The bead was flatter and the penetration more consistent. It did get a bit hot towards the end and I was rushing, but probably some flicking up of the torch would have controlled things.

    Here are a few shots of my feeble attempts at mimicking the Masters. Spending a bit more time shearing the filler rod from the sheet (marking it out for a consistent width) helped. Thoughts are that rather than using 16swg for the filler rod, I might be better trying some 18swg for a lower deposition rate.

    Bigger tip was better for me.

    Click image for larger version

Name:	20190526_115535.jpg
Views:	97
Size:	67.8 KB
ID:	1376

    Click image for larger version

Name:	20190527_151705.jpg
Views:	94
Size:	68.1 KB
ID:	1377

    Click image for larger version

Name:	20190527_181347.jpg
Views:	94
Size:	53.4 KB
ID:	1378






    Leave a comment:


  • cliffrod
    replied
    Thanks Bill. Will do. Mum's the word.. Sshhhhh...

    Leave a comment:


  • Bill Tromblay
    replied
    Hi,

    I have had this happen to me. When filling holes, it is easy to be welding around the edge and as you fill with rod you cover over and not weld a part of the edge. The edge can be the base material or the edge of one weld puddle to the next weld puddle. The weld process, slight oxidation and old flux will cause the material to not flow together and you get this result.

    In a normal weld seam, you travel from one edge to the other, you don't back up or change direction mid weld. This is done for several reason, 1 is pre-heat the panel as you travel, 2 to activate the flux, weld and move on. When doing holes, it is easy to contaminate due the weld going back onto it self.

    If I develop a hole, I continue until I have the seam welded then go back. I clean off the old flux and oxidation and apply new flux. For the smaller holes, I heat the rod and ball up the end until it is the size of the hole. Then heat the part until you see the whole edge of the part become molten, then add the ball of rod. It melts in completely and completely fuses all the way around. With 3/4" (20 mm) diameter hole, it is easier to run a weld bead around the edge until filled.

    It always shows up when grinding or planishing the weld. Technically it is an inclusion and we get it in aviation with the best of them

    Clean, brush, re-weld and hope your friends don't see it

    Bill
    Last edited by Bill Tromblay; 09-18-2019, 05:51 PM.

    Leave a comment:

Working...
X