dknguyen

I've heard that if you overheat it a little bit too much it all falls a part (the guy kind of compared it to a sheet of metal suddenly turning to liquid very abruptly).

Krumlink

Aluminum oxidizes instantly when welded with oxygen present. One of the few ways to prevent instant oxidization when welding is to weld in a argon environment

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MechTronics

World of Warcraft is a disease

Torben

Steel does that too, at least to some degree. Aluminum is supposedly far worse for it though, and where steel glows as it gets hotter, aluminum doesn't--it apparently just develops a kind of sheen that you have to watch for.

I haven't tried aluminum yet, but among things I've read and/or been told are that it has a lower melting point than steel but is a much better conductor of heat so it is harder to get the heat just where you want it without overheating the work piece. If you don't handle this right you'll either cause the rest of the work piece to warp or else just blow through (or both). Also, steel turns straw-coloured, then glows red-orange-white, as you get it hotter; aluminum does not glow this way. It just kind of gets a different look--kind of a "sheen", as I've heard it described. It's not so obvious a change and you need more experience to be able to catch it every time.

I hope to figure it out at some point. I've still got lots to learn on just regular old steel first though.


Torben

Torben

Typically this is handled by the welding machine, if you're using TIG or MIG. If you're welding stick then the flux on the electrode handles it for you.


Torben

Torben

Me too. Too bad PCBs don't have Undo buttons.


Torben

theinfamousbob

Depends on the mistake. Sometimes an X-acto blade makes a wonderful undo tool.

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dknguyen

Too bad they can't redo.

deth502

i like to keep a roll of masking tape around for small components (resistors, diodes, ect...) i place them on the top of the board, tape them down, flip and solder.

deth502

what kind of welding are you doing??

imo, oxy acet is prob the best way to start.

i started on stick, then got a mig, then a oxy acet setup. hope to have a tig someday soon.

i beleive ALL my welds got better once i started o-a welding. its a slow process, if you make your joints right you wont need filler. its helpful cuz its so slow that its easy to see the process of the 2 metals melting together, then you get the hang of watching that, and it helps with other processes.

ive had VERY limited experiance with alum, but yes, its MUCH more dificult. as was stated, you dont see the little puddle forming to know when you get the heat right. you just keep heating, then all os a sudden, you see the "sheen" it easy to spot, the problem is controlling it, imo. for me, it sems, once you see the metal change, the heat then just blows out/vaporises it a about 1 sec, and when i try to reduce heat to hold it ther, it frezzes up again. and yes, oxidization is a real pita with it.

quixotron

Yeah. I am designing some printed dipole antennas for work. Copper tape and exacto knifes work wonders! Those equations on the designers notes aren't quite as accurate as they appear to be, so I have to trim the antenna a bit to satisfy the VSWR requirement.

Torben

The course I'm taking covers the basics of oxy/acetylene, MIG, and stick. So far I feel most comfortable with O/A--and my best welds have all been fillerless too. I have a stick welder at home though, so that's what I use the most. I'm getting better with it. Still not ready for pipelining though.

I'm hoping to convince the wife that I need an O/A rig at home. She does landscape design so hopefully she'll go for some homemade lamps and sundials.


Torben

deth502

lol!!

o-a setups can be found used pretty cheap, its the price of the gas cylinders that gets you. luckily for me, the local supplier went out of business, and the place i worked for owned some tanks. the next nearest supplier would only deal with THEIR tanks that were leased from them, so i got their old owned tanks, and i have to drive about 20 min to get to a shop that will fill them for me

you can really get an eye for seeing the 2 base metals melt together with the o-a method!! the hardest part is not sticking the rod!!

Nigel Goodwin

At Sheffield there's an industrial museum called 'Kelham Island', which I've been to visit occasionally, it's quite an interesting place.

http://www.simt.co.uk/kelham/

The reason for mentioning this, is that Sheffield is one of the most famous metal working cities in the world, and one of the exhibits there is a welding sample from a local college. It's basically a ring of various different metal segments, all welded together (imagine a dart board with a hole in the middle), then sawed through to make a nice even slice and polished. It's reason is to show that all sorts of difficult metals can be welded to each other (with sufficient skill), it's truely an impressive sample!.

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killivolt

Most of your equipment dealers have access to special rods used for wielding aluminum O/A. I believe a bronze alloy that has a low melting point and a special flux coating. Instead of wielding it's more brassing.

This stuff is slick and fast I have had to work with aluminum. What a pain just when your ready to apply the rod to your joint ? it's seems like ice to water 500btu's.

Boom it falls apart into a melted mass.

It works great also if you have to different composition's of aluminum with 2 different melting points.

To bad you don't have something to tell you surface temp. to give you a warning.

Torben

You mean like a Tempil stick?


Torben