Thread: Unimig multi 250 with separate wire feeder

Originally Posted by macmac

Hi all, just bought this machine at very competitive price. Bought it bcoz more control knobs and the looks like a sophisticated machine but now problem comes out. 2 new knobs that I never use before. The Crater Current and Crater Voltage adjustment. What are they? How to use them? How to adjust them right. Haven't tried the machine yet coz waiting for electrician to lay a new 32amp outlet. Help and urgent!
Cheers Phil

I would suggest that they are for adjusting the crater fill settings, (all this is is a lower powered setting to allow you to fill the crater at the end of the weld). Some love crater fill, others, myself included quite happily live without it.
Is this machine 415 volt as this is generally where 32A outlets are used?
I would suggest that the number of knobs is probably not the best gauge of welder performance or quality, so I hope you did a bit more research than just that.

See if you can find a instruction manual online. that will tell the true story

Hi Karl, this machine is single phase but can go upto 250A. This the exact pix of the machine
I want to try the machine but the bloody electrician didn't turn up again. He said he will run me a 6 mil cable with 32 socket and plug. I also think this is the setting of your finishing crater weld but not sure how to adjust them. Should be higher or lower than the original setting. Also I expect there should be another knob for time delay for the crater setting but can't see that extra knob.
By the way, if someone got the same machine, pls let me know how to do the setting.
Cheers, Phil

Hi RVK,
The instruction manual is useless. Didn't explain anything but just tell u the knob is called crater voltage and the other is crater current. It's only few pages with diagrams.

Your crater fill settings will be lower than the welding settings.
A timer is not needed for crater fill, the operation of which will go something like this

• Set the 2T/4T switch to the 4T setting
• Pull trigger - welding will start
• Release trigger - welding will continue, this is known as trigger latching
• Pull trigger again - the welder will drop down to the crater fill settings
• Keep trigger pulled until the crater is filled to your satisfaction
• Release trigger - welding will cease.

I do not know why the sparkie is installing a 32A outlet as this welder should run happily on a 15A outlet, but make sure that the correct circuit breaker is used as a "c" curve breaker will tend to throw out with the surge loads that welders produce.
I took the liberty of downloading the manual for my own interest and you are right - good toilet paper, but not much of a manual.
Honestly I would not get too caught up on the whole crater fill feature, as I said earlier, some love 'em, some live very happily without them.

Thanx Karl. What is c curve beaker? By the way, I expect my electrician will know what is c breaker otherwise I will ask him to go back to TAFE.

Originally Posted by macmac

Thanx Karl. What is c curve beaker? By the way, I expect my electrician will know what is c breaker otherwise I will ask him to go back to TAFE.

The "curve" of a circuit breaker defines the way it responds to an overload condition.
Put simply, some brakers will trip at a very small surge overload, while others will allow the same overload for a greater period. Welders produce quite high surge currents, as do large electric motors upon startup, therefore they need a circuit breaker that will accommodate these surges without tripping out. Sort of like the difference between a slow blow and a fast blow fuse. In the event of a short circuit, all circuit breakers, whatever their curve, will trip virtually instantly due to the massive currents produced under such conditions.

Originally Posted by macmac

Thanx Karl. What is c curve beaker? By the way, I expect my electrician will know what is c breaker otherwise I will ask him to go back to TAFE.

'c' curve breaker is a general house breaker you need a 'd ' curve breaker ( old motor start fuse )

As mentioned, if the sparky's putting in a 32A outlet for a welder that should be tickety-boo with a 15A outlet, then I doubt the trip curve of the breaker will be at all relevant.

Originally Posted by RustyArc

As mentioned, if the sparky's putting in a 32A outlet for a welder that should be tickety-boo with a 15A outlet, then I doubt the trip curve of the breaker will be at all relevant.

Granted, the curve of the breaker will be far less relevant at the higher rating.
As I have mentioned previously I have no idea why a 32A outlet is being installed in the first place. While 32A 250V outlets are available they are an uncommon sight. The cost of installing a 32A service will also be quite high I should imagine, even just the outlet alone will be pricey. All this extra expense to achieve nothing in effect as there are no machines I have seen with a factory fitted 32A plug so the end user will either have to make up a converter lead from say 32A male to 15A female, (which negates any advantage of a 32A outlet anyway) or change the plug on any equipment used to a 32A plug, which will be both expensive and questionable from a warranty position. For those unaware, a 32A 250V outlet is a 3 round pin style similar to a 415V 3 Phase plug, so it has no interchangability with our normal 3 flat pin plugs.
It all seems a very cock eyed way of going about it, far better to use a 15A service, (or even 20A, as these can be on the 3 flat pin platform), with the correct circuit breaker. At least the outlet will be useful for other purposes and not require modification of plugs and leads etc.

Believe it or not, my sparkle friend didn't know what I'm talking about when I told him he must use d curve circuit breaker instead of c curve breaker. Anyway, i suspect he installed the wrong breaker as I saw a c prefix in the breaker he installed. Here it is:


Also, he used 4mm2 cable only as he didn't bring the thicker 6 mm2. He said it should be ok and more than enough. I left no choice but to trust him.
As most ppl here r experts, is it good enuff to use 4 mm2 cable? Cheers, Phil

Originally Posted by macmac

Believe it or not, my sparkle friend didn't know what I'm talking about when I told him he must use d curve circuit breaker instead of c curve breaker. Anyway, i suspect he installed the wrong breaker as I saw a c prefix in the breaker he installed. Here it is:


Also, he used 4mm2 cable only as he didn't bring the thicker 6 mm2. He said it should be ok and more than enough. I left no choice but to trust him.
As most ppl here r experts, is it good enuff to use 4 mm2 cable? Cheers, Phil

what did he charge you to do that ? When my sparkie wired up my shed he told me that 4mm wire can safely take 25amp to30amp and didn't that welder only regurie a 15amp plug? that's a bit over kill if the welder was to have a fault wont that cook the welder instead of tripping the breaker?

Instead of starting a new thread, I think it would be ok just continue a relevant topic to the same thread. I'm now in Melbourne attending boat building course at Plate Alloy Australia for five full days. First of all, I always think using mig for aluminium welding is a lot lot harder when comparing to steel welding but I was wrong. In fact, I think aluminium welding is lot lot easier than steel welding especially when u r using pulse mig machine. There r 3 different machines we r using in this course. They are Fronius 2700???, T&R multi 250 and unimig inverter 250. Of course, no need to say, the Fronius is totally champion in terms of functions and user friendly. I mentioned that even someone never weld before can produce a very good result by using this machine but the price of this machine is skyrocket high. However, The T&R multi 250 is not a bad machine and it also performs very well. It is user friendly as well and the cost of machine is only one third of the price of Fronius. The result of the welds are similar to tig welding but not as beauty as the result of Fronius. But comparing to unimig inverter, u may say it's totally uncomparable as U may find u need a lot of trial and error before u get into the right setting. Different positions of weld also requires different setting which means u have to readjust again and again whenever u change the position of welding.
A bit disappointed after tested the T&R simply bcoz I'd already bought the unimig inverter. I'm not saying unimig is a #### machine and in fact it is a very good machine for beginner to start. I will say if you can handle the unimig easily, then using T&R or Fronius is a piece of cake. If you are doing a lot of aluminium welding and your budget is limited then T&R is a go. Probably it is the cheapest pulse mig in the market with a lot of functions.
This machine is the one originally I'm after but becoz my TAFE teacher commented on this machine badly, I changed my mind and go for unimig. I will ask my supplier if he will allow me to upgrade my welding machine when I get back to Sydney. I only used it twice mainly testing the machine after I got the power.
Just want to clarify I have no business or relation to T&R, in fact unimig distributor is same as T&R. I just want to let ppl know that there's an alternative good pulse machine in the market with a fraction of price.
Cheers, Phil

Hi Brendon, my sparkie friend haven't sent me a bill yet but definitely peer price. So is that mean that I should change the circuit breaker to lower amps? Also, u may mentioned that the sparkie installed two 32 amps outlets with the same cable. Is that good enough if I use the two outlets at the same time. I will mainly using for plasma cutting and welding.