Yes. "Official" etchants sounded scary - quite concentrated acids including hydroflouric. No way. But know Al is amphoteric, so tried the alkalis/bases route and "hit lucky" with drain-cleaner. You can get it whenever and wherever you need it, so haven't "refined" the method. You broadly know what the macro etch is supposed to like - and expect to see something like that if you run round the builder's merchant and source the drain-cleaner.
On 3/23/2023 1:09 AM, Richard Smith wrote:
Oh, I didn't say I was good at it.
I'd like to get better, and if I can't with the MIG welder I have I guess I'll have to learn to TIG weld aluminum. I have some large projects I "want" to do, but if I have to learn to use TIG and go slower I will. Just means I might not finish them while I am still young enough to use them.
I started reading a book some years back by a guy named Stephen F Pollard about building aluminum boats. I was hoping for more in the welding portions of the book, but there was not as much as I would like. He basically repeated what this group and SEJW had told me in the past. CLEAN & PREP & CLEAN SOME MORE. The other thing he emphasized was a particular order of processes. Its not always practical of course depending on what you are welding on a boat, and if you are building from scratch or doing repairs to a completed assembly. He said you should always clean and prep, weld one side, then back grind, and weld the other side. I have certainly seen (and owned) a few small (16-17ft (4.8m-5.2m)) welded aluminum boats that were built by commercial builders. My best guess is that they were all pulse MIG welded from one side only. (They have a sort of stack of dimes look, but not as uniform as a skilled TIG welder.) Some welds of course would be nearly impossible to back grind and weld, but most they just welded from one side. I have to assume Pollard was mostly building larger boats. Small trawlers, tugs, etc. The weld, back grind and back weld might make sense on 1/4in (6.35mm) or thicker plate, but full penetration has never been an issue for me with .080 to .125 inch (2mm to 3.2mm) these utility/fishing boats are made out of. The issue for me has always been not totally annihilating the base material.
If I could get the welds to work out like Pollard suggests with the thinner sheet that might be good for me because My projects would be planing hulls, and being able to go back and grind the first side flat would be ideal.
Pollards Book. Amazon:
I am absolutely not saying I am good about any of this or that my thoughts come from a mind of greatness. I'm not even arguing with any of your points. I am just trying to better understand how things work so I can practice better technique.
Snag, sorry about hijacking your thread.
We have had very good luck with stainless pots from the hawker at the carnival. Yeah, no kidding. Its been 10+ years since we started using mostly KitchenCraft made by Americraft for all of our stainless cookware. I would have just walked on by, but my wife insisted. Happy wife and all that... The stuff is expensive. It makes WalMart cookware seem almost free by comparison, but I admit its good stuff.
Tomatoes are certainly hard on cast iron cookware, and probably on low grade stainless. I think a few other nightshade related fruits may also be. Eggplant, tomatillos, etc. My wife uses tomatillos a lot to make sauces using the stainless cookware mentioned above with no issues.
Drain cleaner (also sometimes sold as root killer) is popular for a lot of projects other than their label indicates. Home anodizing often uses it for the "desmut" process prior to anodizing.
Oh don't be ! This is usenet , and whither a thread goeth , there will it be . I've learned a lot from threads that went a different direction midway . This one has been very informative ...
We have had very good luck with stainless pots from the hawker at the carnival. Yeah, no kidding. Its been 10+ years since we started using mostly KitchenCraft made by Americraft for all of our stainless cookware. I would have just walked on by, but my wife insisted. Happy wife and all that... The stuff is expensive. It makes WalMart cookware seem almost free by comparison, but I admit its good stuff.
Tomatoes are certainly hard on cast iron cookware, and probably on low grade stainless. I think a few other nightshade related fruits may also be. Eggplant, tomatillos, etc. My wife uses tomatillos a lot to make sauces using the stainless cookware mentioned above with no issues.
Bob La Londe
------------------------------ I use my mother's 12 quart Farberware stockpot for the stew after simmering the marinated cheap cuts in her Pyrex pot. Almost every household item I own was inherited, since she took care of older relatives and then disposed of their belongings to my sister and me, she having first choice since I didn't much care. We both built a barn to store the excess. I'm still using Mom's first microwave, with a wind-up timer.
The paring knife I use most was a free sample from a peddler with a temporary in-store kiosk. I acted the sympathetic listener and he spilled his life history in electronics to me. That happens fairly often and it surprises me how many people selling crafts or second-hand stuff bailed out of high tech. They claim to value the independence and self reliance and being outdoors. I tasted it one between-jobs summer, working a Renaissance Faire, and admit its attraction though I went back into the lab at Mitre.
Many people misunderstand the profit gained in achieving happiness ;-)
I'm running towards the limit of my ability to "profess".
Different thicknesses caused unequal fillet legs, as those welds had restricted access and I couldn't tip the torch off 45deg to correct for that. Other than that, no other effects as I saw. Was about 230A and 25.something Volts.
I never more than wire-brushed my Ali for these Ali-GMAW fillet welds.
They insist you must only use stainless wire brushes on Ali - but they would have none and no way I'm bringing my own onto site. I believe stainless wire brush is better - but anything is better than welding over weeks, months and years of oxide build up.
Back-grind - that's for full-pen. butt welds? Makes sense.
I've said my piece, especially with that article. You pick your best way forward.
BTW - the TIG'ers were making things like fuel tanks from 3mm sheet. Mainly outside-corner joints. Absolutely the process to use for that application. It's a languid process, at the unmissable benefit that you get pressure-tight first-time every time.
I've seen "the unmissable advantage of TIG" applied at Ali 25mm thickness T-fillet and it looked to me like a farce. Ali-GTAW for sheet / thick-sheet thicknesses; Ali-GMAW for plate. As it seems to me.
Okay, while everyone's here and interested...
How would I GMAW Ali from a lead-acid battery, like from a truck?
For "spray" the Voltage (and Amps) is "as flat as a billiard table". So what a battery supplies should be ideal. At about 200A to 250A and 25V to 26V. (but Voltage is very sensitive - a fraction of a Volt makes a visible difference).
That 200A to 250A - a lead-acid battery can supply for a time? As you might want if you are doing short or test welds in your shed.
The salient feature of lead-acid batteries compared to other battery types is the ability to supply a high peak current - like for a starter-motor...
The Amps is regulated by the wire-feed-speed. No other control needed for Amps.
You'd probably have a spool-gun, by the way.
[the idea comes from apparently for steel a "gasless FCAW" / "innershield" that a professional welder eg. going up in a "cherry-picker" can have a spool-gun and a pair of 12V batteries in series]The "problem" (?) is the Voltage. Which the supply must have a means for the welder to control. A fraction of a volt makes all the difference...
The fully charged voltage of a "24V" battery - or 2 off 12V batteries
- should be 25V to 26.4V (?)
26V is "it". How would you "top-up" the voltage by 0.5V to 1V? I assume that for a tiny bit over Voltage a bit of resistance would "do the trick".What you are avoiding is (* 250 26 1e-3) 6.5 kW of arc power, which would be (* 250 26 1e-3 2) 13.0 kW at the wall-socket for a copper-and-iron GMAW machine. Then you have a big machine to store for only little jobs.
Yes any commercial welding at a customer site and you have a big industrial CV&Pulse 3phase machine - but that's not what's being considered here.
This is about turning-up with a trialed and proven welding procedure specification. Yes they can pay $lots for qualifying to OSI54321. But where chapter-and-verse you've done test-welds mimicking the customer welds and you know exactly where you are going with it. You already have
Or the task is doing an Ali structure of your own.
On domestic supply you've got a battery charger running continuously, which is protected from the welding draw on the battery(s) by the ability to deliver current of the lead-acid cells...
I've described this whimsical idea...
Could this be done? Or, comprehending what the objective is, is there a better way of doing it?
(* (/ 24e0 2) 2.1) 25.200000000000003 (* (/ 24e0 2) 2.2) 26.400000000000002
You know of the Ready Welder?
Looks like there's some more advanced machines too:
Okay, while everyone's here and interested...
How would I GMAW Ali from a lead-acid battery, like from a truck?
For "spray" the Voltage (and Amps) is "as flat as a billiard table". So what a battery supplies should be ideal. At about 200A to 250A and 25V to 26V. (but Voltage is very sensitive - a fraction of a Volt makes a visible difference).
That 200A to 250A - a lead-acid battery can supply for a time? As you might want if you are doing short or test welds in your shed.
The "problem" (?) is the Voltage. Which the supply must have a means for the welder to control. A fraction of a volt makes all the difference...
The fully charged voltage of a "24V" battery - or 2 off 12V batteries
- should be 25V to 26.4V (?)
26V is "it". How would you "top-up" the voltage by 0.5V to 1V? I assume that for a tiny bit over Voltage a bit of resistance would "do the trick".On domestic supply you've got a battery charger running continuously, which is protected from the welding draw on the battery(s) by the ability to deliver current of the lead-acid cells...
-------------------------
This is sort of on my plate, though I rarely use over 50A.
Batteries have a source impedance / internal resistance that is a combination of actual Ohmic resistance in the Lead conductors and the result of locally depleting the electrolyte faster than it can diffuse into the plates. The source impedance is unavoidably in series with the load and it causes the terminal post voltage to drop as current increases.
What I've seen using a carbon pile (variable resistance) tester is the terminal voltage dropping below 11V at my typical starter currents of about
150A, to start my truck's 2.3L engine. The battery acceptance spec is at least 10V out at the starter current draw. It's related to the CCA, Cold Cranking Amps, rating by some mystical marketing formula.I own a Harbor Freight carbon pile load tester which may have been discontinued and it's been a good tool to investigate the performance of a battery under a load of up to 500A, for 15 seconds.
Starting or SLI (starting, lighting, ignition) batteries are optimized for brief high current followed immediately by full recharge from the running engine. They have a poor reputation for short lifespan if discharged deeper, as in a solar power installation. Deep Cycle or Marine batteries can provide current longer at the expense of higher internal resistance and voltage drop under load from differently optimized internal construction. I haven't tested forklift or golf cart batteries.
A battery charged at 14.4V and then loaded will almost immediately drop to its 12.6V rest voltage minus the internal resistance drop, then slowly decline as it discharges. If you have a powerful enough charger they can be operated in the range of 12.6 to 14.4V and serve as an AC ripple filter, as they do with a vehicle alternator whose output isn't steady, but the charger shouldn't jump higher when you stop welding, and that's difficult to design on the cheap.
I converted a 50A buzz box AC welder into a variable voltage battery charger but it's not an amateur's first project and some components would have been impractically expensive if I hadn't scrounged them at a ham radio flea market.
I have no experience with heavy duty truck alternators and designing an adjustable regulator for one is above my pay grade. A circuit that increased or decreased the voltage from the battery to the regulator voltage sense input by an adjustable percentage might fool a fixed regulator into changing its output, but it would have to be extremely reliable or the alternator could go to full output without a load and fry the batteries and truck's electronics. I built a machine for GM that simulated that fault.
-jsw
I was just thinking of that. I've never seen one in use.
For "spray" the Voltage (and Amps) is "as flat as a billiard table".
----------------------
A Buck-Boost converter can change a variable DC input voltage to an adjustable regulated output voltage that is higher or lower than the input. It's possible to create what you want though I haven't seen one that powerful.
Looks like there's some more advanced machines too:
------------------------
I don't see any hint that it contains an inverter circuit to boost or regulate the battery voltage.
The "problem" (?) is the Voltage. Which the supply must have a means for the welder to control. A fraction of a volt makes all the difference...
The fully charged voltage of a "24V" battery - or 2 off 12V batteries
- should be 25V to 26.4V (?)
26V is "it". How would you "top-up" the voltage by 0.5V to 1V? I assume that for a tiny bit over Voltage a bit of resistance would "do the trick".---------------------------
A Buck-Boost converter can shift DC voltage up or down by a fraction of a volt and hold it there as its input battery discharges, so if you can find a big enough one it should do the trick. One of mine can efficiently convert
12V or 24V to anywhere between 0.6V and 36V. Single purpose Buck (decrease) or Boost (increase) voltage converters may not operate close enough to their input voltage.For portability Lithium batteries offer considerably less weight. The limiting consideration is that they have lower current capacity which may be controlled by an internal current limiter, to protect them from damage. They can be connected in series for more voltage and parallel for more current to an extent limited by the rating of the internal circuits, since if a fault occurs the transistor for one may have to handle the current or voltage from all.
There used to be mechanical motor-generators that converted voltage or frequency, perhaps you can find one gathering dust. I have one that converts
28V DC to 250V DC for a WW2 aircraft radio, and there was one at work that converted USA 60Hz to 50Hz to run machines ordered from Europe. I had to learn and make a machine meet all the safety standards for Norsk Hydro.
We were at Palisades Lake near Idaho falls Idaho probably around
1962-3 , Uncle Bill's boat motor had a problem with the starter/generator . A loose wire on the commutator threatened to ruin our weekend of fishing . Dad improvised a carbon arc torch from a set of jumper cables and the carbons from a couple of D cells , remelted the solder to reattach the wire and saved the day . The thing that really stands out about that weekend though was the blueberry pancakes made with wild berries we kids picked .
I didn't know of these. Had I searched the Web I'd have not known what I was looking at. Not my area of expertise.
Thanks everyone on "battery powered spray-Ali-GMAW" idea.
Given that a fraction of a volt is the typical range of adjustment when spray-MIG'ing Ali, that the voltage is likely to drift around, from at strike-up to during the weld run; in time with more welding; etc. suggests you wouldn't bet much on such a "direct coupled to the batteries" solution working.
This would always be about wanting very exact welds (not some "emergency" device where anything which gets you going on having some breakage has done its task - thanks that heartwarming story including wild blueberries).
If I ever had a spool-gun and a couple of 12V batteries I'd be curious to see what happens. It can be difficult to guess. As I've mentioned - the methods which got me my Doctorate shouldn't have worked at all but there's something going on which as far as I know no-one yet understands (?), which made them work. And showed what must happening in commercial welds everywhere.
Okay......
There is a completely different method to get to the same outcome. I have a Miller TIG (GTAW) inverter which can do Ali. And finally I have an outbuilding where I can do my things. I can do proof-of-concepts with TIG. Anything promising - tips odds in favour of hustling use of industrial MIG (GMAW) machine.
Thanks everyone. Rich S
Thanks everyone. Rich S
-----------------
On further reflection I think a Buck-Boost converter or adjustable voltage regulator offer the most promise, though I don't have a source for either. The converter could be close to the spool gun to bypass resistive drop in the battery cables from the truck and give you nearby control and monitoring of voltage and current, perhaps even record it to compare to welding properties.
Perhaps they could help or know of someone else:
I've found several applications for separate raw power sources and adjustable voltage/current regulators. A buck-boost converter added to my DC freezer control regulates the DC power brick down to battery float voltage and limits recharging current after a battery-powered grid outage. A Schottky blocks backflow. It's a simple home brew DC UPS.
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