Thread: UniMi 240 - help please to get started

This may help

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

not quite sure of your model tho

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...

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...or-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...

Originally Posted by MKeech

1. I'm using gasless wire 0.8mm, welding mild steel and gal steel, ranging from 4mm to 10mm
2. 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.
3. 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
4. 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)
5. Pregas - as I am using gasless, I assume this is not relevant. Turn it off
6. Rampup - not sure what to set this at??? Starts arc softly and it will increase as weld progresses
7. Burnback - not sure what to set this at? Adjusting it controls wire from burning back to tip and sticking.
8. Time on - assume this only applies to stitch, spot etc welding Turn off
9. Pause - assume this only applies to stitch, spot etc welding Turn off
   
10. 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

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.

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

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

Originally Posted by Zwitter

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

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

Originally Posted by Grahame Collins

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 .

Stuart

*that may not apply to inverter welders.

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.

Originally Posted by Stustoys

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 .

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.

Originally Posted by PDW

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

Originally Posted by Grahame Collins

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.

Originally Posted by Grahame Collins

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.

Originally Posted by Grahame Collins

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....

Originally Posted by Grahame Collins

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