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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Hmm, Argoshield is the gas normally used for Mig isnt it ?
I hadnt heard that you could use that on a Tig for steel work, interesting,
I might have to try that out until I get my AC Tig if it gives better steel results. In what way would you say the steel result is better ?
regarding Gas prices, shop around and play off the big suppliers against each other. I got my Argon bottle refill price cut nearly in half by telling SupaGas about a special deal that BOC was offering that I was thinking about and they matched and slightly bettered it, cutting my bottle refill from about $175 to $100 (for 6.8m3, Supagas run some sort of extra high pressure bottle that fits 6.8m3 (compared to the usual 4.0 to 4.2m3) in an E size), so its worth talking to them instead of paying sticker price.
Those disposable bottles are a complete joke. You get about 5 min of welding time out of them, dont even go there.
Converting an inverter arc to a Tig. I tried that, and it does work, but you have to "Scratch Start" the arc, just like starting a stick electrode.
The problem is, as a novice, I quite often scratch-*stuck the electrode trying to start it, which then requires panic'ed wiggling to break it free (since you dont have a power switch on the trigger with a converted arc welder, power is on all the time), destroying your tip point, sometimes breaking the tungsten off.
And if you mis-manuever the torch, the arc goes out, and you have to scratch again, which means either waiting until your weld puddle cools and starting again, which makes for ugly welds, or if you dont wait, you dip the tungsten in the weld pool trying to restart it, and get a big blob on the tip, requiring re-grinding your tip if you want to keep a nice arc.
After a few frustrating weeks, I gave up and bought a Tig with HF (High Frequency) arc start. you just press the button, and zap, it lights the arc with no contact at quite a long range. Accidentally get too far away with a wiggle and the HF automatically kicks in again, keeping the arc going while you re-establish a nice short arc length.
It also lets you "long arc" for a second to spread out the heat input while you change direction, or reposition your filler rod or something, without the arc going out.
Its probably a bit of a noob-crutch, since I got a stainless steel fuel tank professionally tig-welded back togther after mods, and I watch the guy do that with a simple scratch-start arc-inverter/tig rig, and he just lit up first go with a practiced flick of the wrist and motored on out without a problem.
"You make it look easy !" I said... "Yes, well, 15 years of experience will do that" he said.. OK, but Im not sticking electrodes for years, so I like the HF start _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Sun Nov 22, 2015 12:54 pm |
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maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
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Hm, my gas supplier seems to be very friendly then.
I pay €25 for a filling of 2.5m³ pure argon.
Mixed gas (argon with a dash of CO2) isn't that much cheaper.
And as I weld steel, cast iron, hardox*, stainless steel, aluminium and titanium, most of the jobs require pure argon.
For normal steel and cast iron, mixed gas is an advantage tough, gives better burn in. But to change over the bottle each time, nah.
*hardox doens't have a real advantage with mix gas to my feeling.
@ Nick. Water cooled torch. The welder itself is a cheap chinese AC/DC TIG job.
The original torch overheats every time I go over 120 amp (160 on the readout), and that's regulary on welding long stretches of 3.2mm hardox or 10mm ali.
An overheating torch means the copper locking collar anneals and gets very soft deforming and pulling the needle out of center. Or even losing grip so the needle just falls out after a serious bit of welding.
I had the luck to know about water cooled torches due my experience as a photo-welder in the past, so it was logical to use a watercooled torch. (€90 via Aliexpress, including consumables) .
The watercooled hose is stiffer, but the torch is lighter than the gascooled one. So it cancels out.
The main disadvantage is the cheap set I made. I use 2 diaphragm pumps in parallel to push the water trough the 5 meter of hose. It's noisy and I can feel the pulses in the handle.
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Sun Nov 22, 2015 5:05 pm |
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maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
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@Nick,
My watercooling unit is actualy a recycled, huge industrial unit, and it contains what you list up. I added a cheap digital thermostat/relay from aliexpress, but I never have seen the watertemperature rise with 10° over ambient.
Before you heat up 15 liters of water, you're doing some serious welding tough
I'm planning to build a new welding table, and integrate the reservoir in one of the legs. No radiator or fan , the reservoir will be large enough to dump a lot of heat in it.
The pump should be capable of pushing 5 l/min @6 bar.
A rotary vane or gearpump sound the most realistic.
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On welding titanium. If you can do it in a glove box , you can keep it flooded in argon, avoiding any contamination of the welds or base material.
Otherwise, get a bigger regulator, make a splitter on the hose and keep the argon flowing around the welds, including the backside.
Ti also behaves differently than steel or ali. The welding puddle is a lot more viscous and the filler melts in slow fat drops.
The bad heat conducting qualities of titanium are another matter and makes for a different way of thinking about warping and handling.
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Mon Nov 23, 2015 3:40 pm |
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