UniMi 240 - help please to get started

[MKeech]

I recently bought a second hand UniMig 240 to upgrade from my old CIG stick welder which I've had for 30 years. I'm a weekend warrior and the world's worst welder despite taking myself off to TAFE years ago to try to learn how to do it properly. No matter what, I still have only just got my hand in by the time I finish a job and then have to do the same thing next time I have a welding job to do.

I had hoped the UniMig would answer all my problems and make welding a dream. Alas over the last weekend I couldn't even get up and running. I've downloaded a UniMig 240 manual which is next to useless as it basically only tells you what each control does; but it doesn't give any info on what settings to use. For instance it tells you that the S mode is for adjusting Wire Speed, which is helpful but the next question of course is what wire speed should I use? I haven't got a clue. After lots of trial and error I gave up because I couldn't maintain an arc so no welding actually happened.

Because I couldn't find any info on what the settings should be for each variable, I don't know whether I have the settings wrong and its never going to maintain an arc on current settings or if the settings are ok and it's pilot error. So - help please from anyone who can help me with the most basic questions on getting started:-


I'm using gasless wire 0.8mm, welding mild steel and gal steel, ranging from 4mm to 10mm
Amps - The manual says there are 8 voltage settings:-
a. I assume the Power Regulation knob on the front of the unit adjusts voltage (no reference in manual at all??)
b. Does this knob adjust both voltage and amperage simultaneously?
c. How do you know what voltage and amperage is appropriate to the job? (would be nice to have a guide table??)
d. How do you know what voltage/amperage equates to each setting on the knob (1-8)?
Mode - I have set it to Manual mode (2) which I assume is appropriate for basic gasless mig welding but please advise if something else is appropriate eg Automatic
Wirespeed - How do you know what wire speed to choose? (I was pulling the trigger to get the arc started but with the arc stopping and starting all that happened was more and more wire feeding. I ended up with multiple short pieces of wire stuck to the job from the initial arc which then fizzled and broke off about 70mm back. More wire then just fed out which I had to cut off. waste of wire if nothing else)
Pregas - as I am using gasless, I assume this is not relevant
Rampup - not sure what to set this at???
Burnback - not sure what to set this at?
Time on - assume this only applies to stitch, spot etc welding
Pause - assume this only applies to stitch, spot etc welding
Anything else critical to making the thing weld? - appreciate any and all help.

cheers

[DocBug]

This may help

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

not quite sure of your model tho

[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...

[Jekyll and Hyde]

The link below might help a little bit with the basic machine setup and process, and I think from memory if you browse around the site it has a fair bit more information.

(http://www.millerwelds.com/resources/articles/MIG-Welding-The-Basics-for-Mild-Steel/)http://www.millerwelds.com/resources/articles/MIG-Welding-The-Basics-for-Mild-Steel/

It's not too helpful in terms of settings though. the main ones are voltage and wire feed, but check that your burn back is set to a low number - it sounds like you have quite a bit of wire coming out after you release the trigger?

Very rough guide to voltage and wire speed, if the wire is melting in blobs before it even gets to the weld pool, feed is too slow (or gun is too far away!), if the wire is hitting the steel and pushing the gun away, feed is too fast.

If the weld bead is really just sitting on top of the metal, probably could do with a bit more voltage. If you've got a really wide sunken bead, little less voltage might help.

Worth noting though, that sometimes too much voltage can look like not enough wire, and vice versa, it is a bit of a balancing act. If you have some 4mm plate, set your voltage to 5, and start with the feed around 26, and run some beads Then after a few goes, try turning the wire feed up and down from there. I actually seem to remember the gasless wire I had ran better with a surprising low wire speed, but I could be wrong. You should be able to get some reasonable beads down with feeds between 18 and 32, if I'm remembering correctly, but there will be a sweet spot for your own travel speed...

[Grahame Collins]

I'm using gasless wire 0.8mm, welding mild steel and gal steel, ranging from 4mm to 10mm
Amps - The manual says there are 8 voltage settings:- Amps is relative to wire speed -more wire speed - more amps.
a. I assume the Power Regulation knob on the front of the unit adjusts voltage (no reference in manual at all??)If this POWER REGULATION knob rotates through without stops -it is the Amperage dial !Somewhere there will be a knob that has 8 clicks -that will be the the voltage steps
b. Does this knob adjust both voltage and amperage simultaneously? Definitely not ! Amps and voltage are adjusted on separate controls.
c. How do you know what voltage and amperage is appropriate to the job? (would be nice to have a guide table??)
d. How do you know what voltage/amperage equates to each setting on the knob (1-8)? The knob with 1-8 steps gradually increases the voltage a bit at a time.
Mode - I have set it to Manual mode (2) which I assume is appropriate for basic gasless mig welding but please advise if something else is appropriate eg Automatic
Wirespeed - How do you know what wire speed to choose? (I was pulling the trigger to get the arc started but with the arc stopping and starting all that happened was more and more wire feeding. I ended up with multiple short pieces of wire stuck to the job from the initial arc which then fizzled and broke off about 70mm back. More wire then just fed out which I had to cut off. waste of wire if nothing else)
Pregas - as I am using gasless, I assume this is not relevant. Turn it off
Rampup - not sure what to set this at??? Starts arc softly and it will increase as weld progresses
Burnback - not sure what to set this at? Adjusting it controls wire from burning back to tip and sticking.
Time on - assume this only applies to stitch, spot etc welding Turn off
Pause - assume this only applies to stitch, spot etc welding Turn off
Anything else critical to making the thing weld? - appreciate any and all help.Check terminal connections -electrode polarity is different on gasless.

cheers

I think you need to do a lot of restudy on basic use of gasless and mig.I do not want to sound crtical but if you don't get you head around the basics it will cause you heaps of problems, More later.

Grahame

[jatt]

For what you pay, found they arent a bad machine. But thats just my opinion.

Would post up a foto of mine, but the attachment section aint playing the game tonite for some reason.

With my machine. For material thickness 4 mm would run it at least 7, especially if if its for short runs.

thin stuff 5 -6. Once item is hot, at times dropped down to 4.

Aint a welding guru, but found for 6mm and over, reach for the arc.

Only have used mine with gasless thus far.

Only my 2 bobs worth. had my machine about 5 years now.

[Grahame Collins]

If you can post a decent size readable photo, I should be able to help you decipher the controls.
I don't understand why the manual is of little use. EDIT Oops now I do- - I have just read the manual and its one of the poorest efforts I have seen in my career. It is dreadful!
We will have to go through it and turn it back into english.

Most MIGS and FCAW machines display a current selection chart on them somewhere. Don't forget earth connection + for gasless.

To get it running half way decent set the voltage around the 4th step and then dial the wirefeed until it runs in a stable manner. If you can't do it alone get someone to dial in the wire feed.
Cut a new end on the wire with the sidecutters each time you want to re start the welding and make sure the earth clamp is connected to a fresh clean surface.

Grahame

[Zwitter]

Hi mkeech

I just upgraded to an electronic single phase mig. But still stuffing around getting a high amp socket where I need it.

I would advise you tube. Some great courses on there. There are some about mistakes and you get to hear the sounds and see the mess. The cooking bacon sound is what you want.

Check the specs of the wire you have as not all gasless wire is opposite polarity. I think it was once but these days the range is very impressive. I bought some gasless stainless!

Surface prep is very important. I would say get some scrap bits and set voltage then weld at various wire speeds until it sounds and looks right.

Good luck

James


Sent from my iPad using Tapatalk HD

[PDW]

Check the specs of the wire you have as not all gasless wire is opposite polarity. I think it was once but these days the range is very impressive. I bought some gasless stainless! Where from, if I may ask? I could do with a spool or 2 of gasless stainless wire. I've still got a lot of solid wire in 309 & 316 but my DC spool gun is what's going on my boat. I agree about the inverter welders. I have 2 MIG welders, an old transformer type 3 phase 250A unit and a new Chinese made Magnum 250A unit. The new one is far, far, far superior to the old JIC welder both in performance and duty cycle. PDW

[Grahame Collins]

Some points for Welding with gasless wire


Hand piece is dragged not pushed
Wire stick out around 25mm from contact tip
Use the correct drive wheels suited for gasless wire .I am not a fan of serrated wheels as they tear the wire which as .8mm is far too small for a gasless application.This is an area that the operator needs to tweak.I favour going up a size in tip diameter .say if .8mm go to .9mm.
Change or clean the liner on a regular basis.
Ensure spring on spool axle is just tight enough to prevent overoll
Do not screw down wire feed wheel tension too tightly-only tight enough to get the wire moving and not much more.
Remove nozzle – only needed for gas cover mode
Clean earth contact area
Change physical earth connection to earth positive.
Nip off the ball on wire end each time to gain a good weld start


Grahame

[Stustoys]

Remove nozzle – only needed for gas cover mode

Just a word of warning here*.
I'm told the diodes arent rated for dead short, with the nozzle off you risk a dead short. If or how long you will get away with it is anyone's guess :D.

Stuart

*that may not apply to inverter welders.

[jatt]

Yes you must be careful if you remove the gas shield. Tried this once on my 240, never again, as Stustoys pointed out. Have a shield where I cut some off it, but not too much as to expose the tip.

If I fire the old girl up in the next couple of weeks (if you are interested of course) can write down what I have my settings at. Of course I have set it up to what works for me. Prob PM is best

As previously mentioned by Mkeech the instruction manual is a about as good as *%$# full of cold water, so one wont achieve much by looking there.

If you get a "HOO" reading come up, its a thermal thing I recon (prob see it in the warmer weather), then let it cool down for a bit. My fan isn't always on, can only assume this is normal with this unit.

Also have sml inverter from Unimig.

[Grahame Collins]

Just a word of warning here*.
I'm told the diodes arent rated for dead short, with the nozzle off you risk a dead short. If or how long you will get away with it is anyone's guess :D.

Stuart

*that may not apply to inverter welders.

Stuart ,Is there any manufacturers information to this effect. Its sounds dead wrong to me.

Those of you who have welded galvanized metal with mig will be well aware the the space between the contact tip and the nozzle or shroud can and does build up with spatter.
Thinking about it logically, when welding with nozzle on , the spatter could fill the space between contact tip and nozzle and arc it out.I have lost quite a few nozzles on migs,this way.

Therefore all inverter mig and gasless machines ( that require a nozzle for gasless) have the potential by their construction for this to happen.
To strip spatter from a nozzle is a pain in the butt even in a MIG mode at the best of times.With the gasless set up welding gal it would be worse.

I have personally witnessed nozzles so packed with spatter that they arc out by virtue of direct circuit between ground to nozzle to spatter and then to contact tip. When I say arc ,I mean a big chunk disintegrating the out of the side of the nozzle. For this reason I had always used a mig unit- in the FCAW mode with no nozzle- hence my advice was given on that basis.

Surely manufacturers would not build the units so poorly that the machine needs repair after a minor incident like that. a quality machine would sport an overload botton or a slow blow fuse like the old tranmigs.

[Oldneweng]

Where from, if I may ask? I could do with a spool or 2 of gasless stainless wire. I've still got a lot of solid wire in 309 & 316 but my DC spool gun is what's going on my boat. I agree about the inverter welders. I have 2 MIG welders, an old transformer type 3 phase 250A unit and a new Chinese made Magnum 250A unit. The new one is far, far, far superior to the old JIC welder both in performance and duty cycle. PDW

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

[Stustoys]

Stuart ,Is there any manufacturers information to this effect. Its sounds dead wrong to me.
Other than straight from the man at Hobart welders when I bought mine 28 years ago, No. We were discussing using carbon electrodes.


Thinking about it logically, when welding with nozzle on , the spatter could fill the space between contact tip and nozzle and arc it out.I have lost quite a few nozzles on migs,this way.

Yeap, been there done that and no smoke came out. But I would say there was a fair difference between 5mm of splatter and contact tip to work piece.



Therefore all inverter mig and gasless machines ( that require a nozzle for gasless) have the potential by their construction for this to happen.
As I said I dont know if it applies to inverters....



a quality machine would sport an overload botton or a slow blow fuse like the old tranmigs.
Whether that would work or not would depend on a few things.

As with a lot of these things you likely have to have a few things going against you before you have an issue. Maybe its not such an issue these days anyway......Whats a set of diodes worth? they used to be BIG $, likely $3 each these days lol

Stuart

[jatt]

Whether it should happen or not, after having the tip arc out when I removed the nozzle.....
My unit still seems to go fine, but its not something I will be doing again any time soon.

My advice is (for all its worth) dont do it on this machine.

[PDW]

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/400585147247?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107 \n I'll get some for the boat - yeah it's expensive but so is renting gas bottles. PDW

[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 :D

[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

[PDW]

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

[Oldneweng]

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

[Grahame Collins]

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 :D


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

[PDW]

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

[MKeech]

This may help

http://www.bjhowes.com.au/Unimig%20Procraft%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.

[MKeech]

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.

[Zwitter]

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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[Metalman]

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 :D


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

[Gerbilsquasher]

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....:oo: 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 :)

[Karl Robbers]

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.

[Ueee]

I just bought a UniMig Razor 205, Mig Tig Stick (or is that Mig Stig Tick? Mmmmm, Stig welding:D)
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