restore project gone wrong cast alu weld failure - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 23, 2023, 10:42:31 pm
content: I dont claim to be a welding expert of any sort,when i need something done I always visit an expert,even then it went horribly wrong, 1960 old thin walled cast alu case was broken,It almost exploded when we tried to welded it together,obviously it is a special mix of materials, not suited for normal alu welding,if any if you know how to weld this sort of material, please tell me ?it is not the first time, or the last time I need to repair a broken cast alu case from that 1960 era.anyways, I ended using epoxy, the strongest type I could get, and sanding a few times,I was able to save the terrible welding mistake.incase you like to see the restore stuff I talk about see here: at 10 mins.Philips EL6415 tube mixer 4ch amplifier 1960 restore improve repair teardownhttps://youtu.be/OWu4Q0sCCJw

author: Benta
author_rank: Super Contributor
timestamp: December 23, 2023, 10:57:54 pm
content: I'd never try welding cast metal, particularly aluminium.For cast iron, there's a technique called "stitching", but even that needs a real expert. And in material as thin as yours, it likely won't work.Your fallback to Epoxy is probably the best idea.

author: Fryguy
author_rank: Regular Contributor
timestamp: December 23, 2023, 11:46:18 pm
content: You could try to solder it - there is special flux and solderwire for aluminium available on the net - i got some of that stuff here and it works ! I would never try to weld something as fragile as this . I don't say it is impossible , but i would never try it for the first time on a unit i absolutely want to save .

author: coppercone2
author_rank: Super Contributor
timestamp: December 23, 2023, 11:50:05 pm
content: its loaded with impurities from casting like casting sand, and porosity, possibly oils too.It will probobly change size when you melt it. Soldering kinda works with the right flux. Brazing Al is crap and super highly dependent on which rods you have.you can watch TIG welding CAST aluminum videos on youtube to see why its hard/impossible.a high quality casting you can possibly weld, like a high end engine block. Some POS like a chinese low cost lawn mower takes a grand master.You need tig, you need the right cleaning setting, you need the intuition and the bare minimum quality of casting to make this possible.Like, you need to weld dirty, bare minimum cleaning, because the cleaning function upsets it too much (but its still necessary).

author: joeqsmith
author_rank: Super Contributor
timestamp: December 23, 2023, 11:53:10 pm
content: TIGI've had the pleasure to have known some very good welders over the years. I would have thought a repair on that would have been a simple project.

author: coppercone2
author_rank: Super Contributor
timestamp: December 23, 2023, 11:54:08 pm
content: he did try tig in the videothe video on some of those shitty casting looks like its melting styrofoam or something.and often, the reason why it broke, is that its porous in that area and too thin, especially if it did not suffer grevious damage. then repairing that is very hardif you read about why some castings are garbage, its because the foundry decided that cleaning the molds out and stuff takes too much time. I herd this about bethlehem steel products (defunct). The symptom is you get sand thrown into your face when you cut it on a cold cut saw. awful materialsyou could file into it and look under a microscope to see maybe.for details on similarhttp://ccc.illinois.edu/PDF%20Files/Reports12/THOMAS-BG%20Particle%20Entrapment%20Criterion%20CCC201202.pdf

author: joeqsmith
author_rank: Super Contributor
timestamp: December 24, 2023, 12:01:03 am
content: An example of a cast case that was exposed to oil and other solvents during it's entire life. Then, it's very large. A heat sink. Aluminum loves to warp.I suspect we are just seeing the effects of a novice.

author: coppercone2
author_rank: Super Contributor
timestamp: December 24, 2023, 12:02:40 am
content: Quote from: joeqsmith on December 24, 2023, 12:01:03 amit might not be total garbage to begin with!I heard of such low quality that sand was literary pouring out of cut steel like a kitchen timer. For like big shipyard stuff. its like bad beef. (yuk)with the quality I see in audio products (i.e. pcb), I can imagine that the casting was VERY cost sensitive.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 24, 2023, 12:07:12 am
content: I would say these cases, actually the whole motorcycle, was disposable. They are low cost and the castings are poor quality. Mix that with people who hog out even more material from them and then ask the designs to handle 2X or more power than they were designed for. Something gives.

author: coppercone2
author_rank: Super Contributor
timestamp: December 24, 2023, 12:11:41 am
content: and the thinner it is, the most chance you have of inclusions and porosity not coming to the surface. The usual things people repair are either thicker, or have a slightly higher quality to them (boat propeller) because they are expected to handle some force. the audio chassis I have zero expectations forand even on a engine, say a bolt hole (comonly broken), you have a big thermal mass near it. its not cooling quite as quick as a entirely thin casting, even though the thin area is contaminated, it stays liquid longer because of the high thermal transfer of aluminum. so it looks the same but I bet in general its cleaner then what you get with a entirely thin casting. IMO it has more chance for gas to get out or go into a thicker structure that can handle it then stay at the extermity. maybe. But I think the bulk of the engine is basically cleaning the extremities (bolt hole flange) a bit even if they end up pretty thin at the end

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 24, 2023, 12:16:04 am
content: >You could try to solder it - there is special flux and solderwire for aluminium available on the netI actually ordered this from amazon, but the seller send me NORMAL aluminium rods !! so they melt at 660C not 300 as claimed, they refused to refund me,so that solution was dropped,now i try stay away from amazon due to the missing support and protection

author: coppercone2
author_rank: Super Contributor
timestamp: December 24, 2023, 12:17:15 am
content: when you try that out keep your blood pressure meds on hand lolhaha is this a prank by the grinch to get someone to try to weld cast aluminum on christmas

author: langwadt
author_rank: Super Contributor
timestamp: December 24, 2023, 12:42:16 am
content: maybe it is Zamak and not aluminium ?

author: Fryguy
author_rank: Regular Contributor
timestamp: December 24, 2023, 12:45:55 am
content: I use this stuff :https://spiesindustries.de/shop#!/products/alu-weichlotNo english website - sorry

author: coppercone2
author_rank: Super Contributor
timestamp: December 24, 2023, 01:18:10 am
content: in the year 500000 we might see a cast pop can process

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 24, 2023, 01:57:01 am
content: >No english website - sorryEs ist kein Problem, vielen Dank für den Link. Schön zu wissen, dass Sie das hier GETESTET haben, es funktioniert.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 24, 2023, 02:30:37 am
content: Nothing about the alloy, it's probably pretty normal stuff (356 alloy, say?), whatever it is, it looks like an absolutely normal aluminum die casting to me. The thing is, die casting means metal injected rapidly into a steel mold, under high pressure -- maybe some air is drawn out before the shot, but metal is rammed in with such force, or water hammer (in the instant while it's still liquid), that myriad air bubbles are entrained, and then frozen in place. Which spatter out on melting, making the stuff nearly impossible to weld.At least, that's the description I've heard of it; I haven't welded it myself, mind. From what I know of the process, it sounds like a plausible explanation. If you can still manage to get purchase on it, sticking melt/filler onto existing metal without it blowing apart in the process -- that's the way to go, and you can look up some how-to videos on it with the above in mind, perhaps. But the few I've seen, anyway, suggest you're better off avoiding melting the damned stuff.The bend in the part -- internal stresses locked in during casting -- seems consistent with it as well. I mean, that it doesn't sit flat on the fracture, but springs out instead and must be pulled into place for bonding. The rapid cooling of the die casting process likely results in uneven stresses. (Possibly the stress could be annealed out, but you'd have to heat the whole thing to nearly red heat, so, it'd have to be repainted at least. And then it'll be much weaker (T0 temper), and good luck trying to harden it. Most aluminum alloys can be quenched from heat, then aged, to develop precipitation hardening (T5 temper), but, good luck quenching something this large and thin.)So, the zinc scratch-rod stuff, preferably* with flux to get good coverage, or tin-based solders, are viable candidates here, as well as the epoxy you went with.*For some values of "preferable". Chemically speaking, uh... not so much?Tim

author: langwadt
author_rank: Super Contributor
timestamp: December 24, 2023, 11:40:44 am
content: Quote from: joeqsmith on December 24, 2023, 01:46:38 ammore like high quality aluminium vs. crap casting

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 24, 2023, 02:50:24 pm
content: thanks a lot tim,that surely could explain the explosion like melt down reaction we saw,no matter how little current or time we tried it was just impossible to melt and weld, without causing much more damage than repair !any one else with similar alu parts on stock from about 1960 are very welcome to try and test and see if there is a way to solve it.meanwhile I am going to order the alu solder stuff Fryguy was so kind and link to,my plan is to learn how to use it, on scrap alu parts, and then i am ready for next time :-)

author: Dan123456
author_rank: Regular Contributor
timestamp: December 24, 2023, 03:32:05 pm
content: Just to check, you know you have to TIG aluminium with AC right? DC TIG will not work and will just blow holes / make a mess!I might have missed that part but figured if mention it as know getting the right settings for the right material can make a night and day differenceApart from that, you can kinda MIG aluminiumI’ve never had particularly good luck with it as it always looks like piles of bird shit but I think that is a skill issue on my part

author: jpanhalt
author_rank: Super Contributor
timestamp: December 24, 2023, 04:10:33 pm
content: Quote from: Dan123456 on December 24, 2023, 03:32:05 pmI was visiting a shop building aftermarket aluminum truck bodies and accessories (like lift gates). They used MIG exclusively on, I believe, 6xxx series aluminum. The welds were beautiful. They did it with the ease of welding clean mild steel with MIG.My experience was with TIG and thin aluminum sheet (e.g,. 0.015").

author: p.larner
author_rank: Frequent Contributor
timestamp: December 24, 2023, 05:14:52 pm
content: think thats bad try welding aircraft duralamin!.

author: JJ_023
author_rank: Frequent Contributor
timestamp: December 24, 2023, 08:16:07 pm
content: So I have welded countless aluminum castings over the years. This is something I have a lot of experience in. I looked at your video. In my opinion it is doable. 1st of all when you did the test I did not hear AC.So here's a few questions for you.What type of welder are you using?Are you on AC?What filler wire are you using?If you have an AC Tig welder I'll be more than happy to recommend settings for you.Also keep in mind that castings often need to be re-welded multiple times in the same spot to clean out the impurities that come up.Each time you have less and less impurities at which point you are able to complete the weld.

author: coppercone2
author_rank: Super Contributor
timestamp: December 24, 2023, 08:51:55 pm
content: I heard the trick to some really bad castings is to not clean it too much because the cleaning setting seems to really disturb the material. but either way its like laying a foundation on a really shitty plot of land IMO

author: JJ_023
author_rank: Frequent Contributor
timestamp: December 24, 2023, 09:25:22 pm
content: I would have to disagree with that. If you're trying to make a repair you need to get enough crap boiled out so that you have some clean aluminum established. Now how far you want to go with that will depend on the piece and the structural integrity that you need.For this particular repair I would do it just enough to fill everything in without any porosity and then utilize some hand filing to restore the original geometry.That's not the only way to repair something like that it just depends on your tools that are available and your competency level with them. For example if epoxy adheres properly to this particular casting I think that would be more than adequate.Epoxy could also be worked with Abrasives to restore the original form and shape of the casting.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 24, 2023, 11:08:12 pm
content: Quote from: coppercone2 on December 23, 2023, 11:50:05 pmCirca 1953, my Uncle got his 1930s Bedford truck engine block brazed.It lasted another couple of decades.They did stuff like that back in the day---for another example, rebuilding crank journals on uncommon brands of crankshafts with a surface as good as original.PS: Sorry, I just "locked in on engine blocks" not realising that we were still referring to aluminium.------ mea culpa!As to epoxy, a workmate once used the type commonly used at that time to seal joints of massive multicore trunk cables to repair the cracked block on his side valve Morris Oxford.It outlasted his ownership of the car.On the other hand, some of the epoxy bought over the counter is pretty much useless.

author: coppercone2
author_rank: Super Contributor
timestamp: December 24, 2023, 11:20:59 pm
content: watch Al braze videos on youtube. They compare rods. Some are shit and some are good. Some rods only meant to make a fat bump on top of a severely damaged aluminum radiator tube.I highly recommend soldering it with the viscous yellow flux and solder. my luck with brazing it is totally fail.also get a wooden brush with steel bristles, not plastic, so it does not melt if you try to scrub it while keeping it hot and stuff. seriously at your own risk.I said this before, when you practice brazing, after you braze, file it down a bit, then pick at it with a strong steel pick. You will see sometimes you have something that looks great but if you jab into it and yank on it, chunks come out.but if its a 1950's engine casting, its probobly good. people actually thought aluminum was amazing and engines were amazing back then so they used to get it right, now its ubiquitous and low cost IMO. I imagine someone actually did everything right and put effort in it because they thought it was some jetsons space age shitThere was a aluminum bit on top of the washington monument because it used to be the worlds most expensive metal. It was like putting a big diamond on the pyramids back then lolalso the braze is really brittle so I don't recommend it for handles. If anything, I would get some thick shim stock and try to just make a big aluminum solder lap joint under the thing to reinforce it after you cosmetically filled in any gaps with stiff braze.and if aluminum was easy the navy would not have so many problems with their aluminum boats lol

author: vk6zgo
author_rank: Super Contributor
timestamp: December 24, 2023, 11:36:44 pm
content: Quote from: joeqsmith on December 24, 2023, 12:01:03 amThe all aluminium block in the Leyland P76 was a higher capacity version of the Rover/"GM reject" V8.It was a nice engine but didn't need a lot of heat to warp----one might even say "at the drop of a hat"!"Line boring" the main bearings was supposed to be standard procedure.Nobody told me, & being used to cast iron blocks, I was amazed when my newly machined crankshaft wouldn't fit.

author: JJ_023
author_rank: Frequent Contributor
timestamp: December 24, 2023, 11:38:03 pm
content: I wouldn't consider brazing a process that is brittle, you can make some very strong and ductile joints with that process. That's too generic of a statement. What are you specifically brazing? What filler material are you using? Is there preheated and post-heat involved? What brazing rod are you using? What is the process for brazing? Oxyacetylene is completely different than tig.

author: coppercone2
author_rank: Super Contributor
timestamp: December 25, 2023, 12:07:08 am
content: aluminum braze is brittle as hell the rods snap like spaghetti

author: JJ_023
author_rank: Frequent Contributor
timestamp: December 25, 2023, 01:02:44 am
content: Depending on how the casting responds the 1st pass you might not even add any rod. Just bring things up to a surface as well as import heat to warm the casting. Then use a carbide burr to cut the top .02" out. Then go at it with filler wire, repeating that cycle as much as necessary to get a sound weldment. If it's oil soaked or really dirty sand filled casting it could take a few tries.

author: MarkT
author_rank: Frequent Contributor
timestamp: December 26, 2023, 01:31:58 am
content: Quote from: oz2cpu on December 23, 2023, 10:42:31 pmNot cast magnesium alloy by any chance? Or an Al/Mg alloy?

author: beanflying
author_rank: Super Contributor
timestamp: December 26, 2023, 02:23:22 am
content: Mixed in here with this link is a rebuild I did on a HP 740B that arrived with a very broken front handle / side casting.https://www.eevblog.com/forum/testgear/hewlett-packard-740b-dc-standard-digital-voltmeter-(and-740a)/msg1419955/#msg1419955There was some oddball Aluminiums used in the 50's and 60's one example was thehttps://en.wikipedia.org/wiki/Birmabrightused in making Land Rovers. Apparently you could use some of it to fusion weld itself if needed but I never needed to on my Series 3 when I had it.

author: JJ_023
author_rank: Frequent Contributor
timestamp: December 26, 2023, 02:53:54 am
content: Quote from: MarkT on December 26, 2023, 01:31:58 amYou could take a few shavings and test it with vinegar. You should get a reaction if it is magnesium based alloy.

author: coppercone2
author_rank: Super Contributor
timestamp: December 26, 2023, 03:10:51 am
content: I don't mean cleaning the weld like preweld I mean the settings for in-weld cleaning might need to be set lowerbut whatever its just something I saw someone on youtube say. I think the little demonstration showed that very high weld cleaning setting (natually what you would want for a dirty casting) caused a problem, but a low setting actually worked nicely, but obviously the weld area was prepped normally.

author: langwadt
author_rank: Super Contributor
timestamp: December 26, 2023, 02:04:07 pm
content: Quote from: coppercone2 on December 26, 2023, 03:10:51 amhttps://youtu.be/OWG1f5e7HEU?si=MHbNZTgzKazKYzkY&t=197

author: coppercone2
author_rank: Super Contributor
timestamp: December 26, 2023, 03:42:00 pm
content: lol @ comments"I was a field service engineer for GM. At one of our training sessions the guys from the plant informed us that they were adding iron powder to the aluminum used in casting transmission case halves, because aluminum has an affinity to the ferrous based molds, which was transferring material to the molds, which caused a lot of work to clean them more often than they would like, eventually ruining the molds, at a cost of over $650k per half. Adding the iron powder to the molten aluminum made the issue much less of a problem. When I earned this the light went on and then I realized why I was having so much trouble welding these castings, just like you are in this demo. Knowing this also made me understand why some of the castings I was seeing were very smooth, and others were not, and that;s because of the aluminum skin being pulled off and attaching to the molds. That's mt story and I'm sticking to it."

author: p.larner
author_rank: Frequent Contributor
timestamp: December 30, 2023, 11:59:21 am
content: ive always found no matter what most ali is a pig to weld,used to use oxy accetalyne back in the 1970's,think its nearly up to welding temp next thng its a molten blob on the workshop floor!.I find tig better.

author: TimNJ
author_rank: Super Contributor
timestamp: December 30, 2023, 09:05:35 pm
content: I have used aluminum filled epoxy to fix cast aluminum and cast zinc/Zamak parts.Smooth On MetalSet A4 is what I’ve used.

author: cncjerry
author_rank: Unknown
timestamp: December 31, 2023, 06:04:31 pm
content: I doubt that is aluminium. It could be a weird alloy and that was why the aluminium filler didn't stick. Probabky would have had better result with a torch and low temp metal filler. Why not just use Bondo or JB weld epoxy? For all the strength that corner needs, that's all it would take to make it perfect after sanding.I had a friend bring over what looked like an aluminum belt buckle. I asked a few times if he was sure, I scraped it down, looked at it with a binocular scope, etc. Hit it with a torch with a very fine ruby orifice, and the buckle did a witch of the west. I could have used TIG but I was worried about the material. It was pot metal, so I cnc milled a small mold, placed the buckle in it and stirred the pieces together with a hot soldering iron.Jerry