Thread: UniMi 240 - help please to get started

Originally Posted by Oldneweng

I mentioned this in a thread, probably last year. Have a look at Bob the Welder. Be prepared to pay money for it tho. I think I was looking at prices around $120 for a 1kg spool. Dean

Thanks for that, last time I looked I couldn't find any. Now it's on fleabay - here's a URL. \n http://www.ebay.com.au/itm/like/4005...=true&lpid=107 \n I'll get some for the boat - yeah it's expensive but so is renting gas bottles. PDW

Sign of the times? Lots of electronics supposedly making things easier to use? Give me my 45 year old Rowenarc MIG anyday, cost me $150 on Ebay, $500 to get it working, and you can cut 20mm plate from the penetration at full noise

Sorry chaps,
I am not trying to be difficult, argumentative or a general PITA, really I'm not, but I am trying to come to grips with the idea that such damage can be done by something that can easily happen inadvertently.

Thats well apart from my original advice as commercial gasless (flux core) non inverter units - Lincoln was one - do not use the nozzle for gasless flux core welding. I seem recall you could get a bakelite fitting to screw on and protect the contact tip and diffuser.Yes I know its inverter applicable, but the whole core of my argument is that a inverter machine should be at least robust to the degree as the previous generation transformer units were.

A dead short between the contact tip and earth is possible in two ways
1 by grounding the uncovered contact tip
2 or The space between the nozzle fills up with spatter and the nozzle arcs out -

Logic says to me if that if it it was done on the older transformer machines ,it should be applicable to the new machines and is indeed it is really harmful to the machine that there should be a BIG warning against this in what passes for a manual.

Never the less I shall contact a few tech departments for the main companies and see what comes back.
Grahame

Originally Posted by Grahame Collins

Sorry chaps, I am not trying to be difficult, argumentative or a general PITA, really I'm not, but I am trying to come to grips with the idea that such damage can be done by something that can easily happen inadvertently. Thats well apart from my original advice as commercial gasless (flux core) non inverter units - Lincoln was one - do not use the nozzle for gasless flux core welding. I seem recall you could get a bakelite fitting to screw on and protect the contact tip and diffuser.Yes I know its inverter applicable, but the whole core of my argument is that a inverter machine should be at least robust to the degree as the previous generation transformer units were. A dead short between the contact tip and earth is possible in two ways 1 by grounding the uncovered contact tip 2 or The space between the nozzle fills up with spatter and the nozzle arcs out - Logic says to me if that if it it was done on the older transformer machines ,it should be applicable to the new machines and is indeed it is really harmful to the machine that there should be a BIG warning against this in what passes for a manual. Never the less I shall contact a few tech departments for the main companies and see what comes back. Grahame

I agree with you and I haven't killed my inverter welder despite grounding the tip out on numerous occasions. Try using 316 or 309 wire overhead and see the spatter build-up. Might be a theoretical problem, hasn't been one in practice. PDW

I have found it necessary to remove the shield on both of my Migs in order to get close enough. I have shorted the tip on a few occasions without any problem. Last night I shorted the tip on the Boc Smootharc 175 and the screen went to what I imagine was a caution warning screen for maybe 10secs and then back to normal.

PDW. A bit cheaper than when I looked last.

I'll get some for the boat - yeah it's expensive but so is renting gas bottles.

Probably worth it for occasional use on boats. I hate having to pay rental for things like gas cylinders just to have them available if you need them.

Dean

Originally Posted by Gerbilsquasher

Sign of the times? Lots of electronics supposedly making things easier to use? Give me my 45 year old Rowenarc MIG anyday, cost me $150 on Ebay, $500 to get it working, and you can cut 20mm plate from the penetration at full noise

Gems like these were built with longevity and brand pride in mind.
We were taught in training that 98% of a migs "break down" problems were mechanical. These days it more like 50% mechanical 50 electrical due to some lower build qualities and cheap cheap electrical components which deteriorate more through heat ,environment and age.I was in a shop in a major industrial plant were the mig had no repair work in 5 years. Its identical neighbor had one component break a solder lug due to vibration.
It was some ceramic thing with lugs each end. These machines were used 7 days a week.

Gerbilsquasher
To equal the quality of your $650 investment you would spend thousands and even then I am not sure a new machine would be effective for the time your unit has been.

Grahame

Originally Posted by Grahame Collins

Gerbilsquasher To equal the quality of your $650 investment you would spend thousands and even then I am not sure the a new machine would be effective for the time your unit has been. Grahame

Probably wouldn't be but - my old JIC 3 phase 250A MIG had a 100% duty cycle of only 140A and 10% duty cycle at 250A. My new single phase 15A inverter MIG has a 100% duty cycle at 190A and 60% duty cycle at 250A. One is on a trolley, the other I can pick up and carry even loaded with a 15kg spool of wire. FWIW I've put close to 20 15kg spools of 0.9mm steel wire through the inverter MIG so far. For a bit over $1000 I'm very well satisfied. PDW

Originally Posted by DocBug

This may help

http://www.bjhowes.com.au/Unimig%20P...t%20Manual.pdf

not quite sure of your model tho

Thanks for your suggestion but unfortunately this is exactly the manual I have already downloaded and found to be useless. I had a niggling worry that I was just a dummy and it made sense to everyone else. But I see that another reply below has looked at this manual and commented that it is the worst they have seen in their career. I don't feel quite so dumb now.

Originally Posted by Jekyll and Hyde

Voltage is controlled by the knob, amps are controlled by wire speed in mig welding.

For a rough starting point, on my Procraft 240 I currently have my voltage at 5 and wire feed at around 26 from lap welding 3mm steel together yesterday, but that's running gas... I found gasless wires bit finicky on the settings, and I could never get a 'nice' looking weld out of it, not like when you knock the slag off an arc weld.

Also check that you have the jump lead and earth lead at the front of the machine in the correct place for gasless welding - earth lead should be on the left, if you're standing in front of the machine.

Finally, without meaning to offend, I get the feeling you might be helped by having a read through some of the Miller welding pages for some instruction in the use of a mig? Things like keeping the wire length short (I usually run around 10mm of stick out from the nozzle when actually welding), and just cut it off if you've got too much hanging out - otherwise you do tend to end up with curls of melted wire stuck all over your part...

Thanks for your tips. I've checked polarity and it's correct. Miller pages have been helpful but still don't give guidance on all settings. However by looking at Google Images I have found some very helpful Miller and Lincoln guide charts. I'll try your suggestions and see how I go.

Isn't technology a wonderful thing!

When I went to tech they
Told me the maximum data speed down copper phone line was 1200 baud! Then in the paper ( no internet) i read some smarty had a quad phase inverted technology that allowed 9600 baud and only sent part of the data and reconstructed the rest. I was suitably impressed. These days we get 1Gb over the same old copper lines.

And welders same deal power in = power out less some inefficiency. These days a single phase 15 amp supply can run a 250amp multiprocess inverter that does MIG, TIG and stick using power factor correction!

Back then gasless was expensive and not all that good. Now it is cheaper and some really impressive wires for galvanized and special situations.

Too bad I am getting older and slower!


James


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Originally Posted by Gerbilsquasher

Sign of the times? Lots of electronics supposedly making things easier to use? Give me my 45 year old Rowenarc MIG anyday, cost me $150 on Ebay, $500 to get it working, and you can cut 20mm plate from the penetration at full noise

I junked a ROWEN ARC 175 a few years ago. If you need any parts, except the transformer and switch, PM me.
Mm.

I haven't had time to look in here because, among other things, I have had to move said Rowenarc to it's new location, all quarter of a ton of it. The wire drive fell off the top of the transformer during shrink wrapping.... still works good.

I'd like a few pics of what you have Metalman, I'd like a few spares to keep my unit going - will send PM shortly.

I love my Rowenarc, it's a graceful machine from a more civilised time.... but to each their own

It's funny that this thread on a Unimig 240 has come up now. I have just spent a fair bit of time getting the same machine up and running for a mechanic. The machine runs very well with solid wire once you have it set, but the menu setup is not the most intuitive of arrangements at all.
There is a way to reset all defaults if you get too far out of whack.

"It is possible to reset the PCB’s original parameter (DEFAULT)
following these steps:
Turn off the welding machine, pushing the on/off switch
(position 0). Push S1 button. Turn on the welding machine,
keeping pushed for three seconds"


I think the advice/caution relating to direct shorting a mig relates more to people that do unnatural things with their mig such as arcair gouging than to accidental shorting out caused by spatter in nozzles. Some migs such as the old CIG Transmig 500's (the blue ones that were copied from a Miller), could arcair gouge, but only once you fitted a gouging kit to them. I don't know what was in the kit. Later Transmig 500's, (the grey ones), had a switch to select gouging mode, suggesting that the required components were already fitted. I don't believe that the kits converted them to CC mode as you couldn't arc weld with them as I recall.
I have gouged using WIA Fabricators, (not my idea or preference), and they don't do too badly with 6mm carbons, but it is a practice that is really dodgy and will shorten the life of your machine.
Generally speaking, the rubber band is wound a lot tighter with newer machines as far as component sizing goes. Where once, a 350A machine probably had diodes capable of handling 500A fitted, a similar machine today is more likely to have 350A diodes fitted.

I just bought a UniMig Razor 205, Mig Tig Stick (or is that Mig Stig Tick? Mmmmm, Stig welding)
I'm blown away by how light and compact the thing is. As PDW says, even with 5kg of wire in they are easy to cart around with one hand. Easy to set and use, the MMA makes using the old peerless coil type welder seem like real hard work.

Ew