Old style Tig Vs Inverter Welders

[TheBrick]

Hi,
I'm looking at welders tig welder on ebay. My my normal route for tool purchase is to buy old and repair / recondition.

When I look at tig welder the new welders from my research use mains -> rectified -> inverter -> transformer -> rectification -> current control -> optional AC inversion stage if required with some sort of HF start stuck on the side of all of that. This obviously allows the unit to be smaller and allows the possibility of the choice of different wave forms.

The old units look like arc welders with a big iron cored transformer of some sort -> rectification -> some sort of inverter circuit (?? what?? variable LC tank) for optional AC with HF stuck on the side of all that.

My question. Other than size / portability what advantage do new inverter base technologies have over the old big transformer units? Can the old units vary their wave form? Is this even an issue? I'd be looking to do mild, stainless and some aluminium. My budget is such that it is either a new R-Tech type welder or a good names old style tig.

 

[overload]

To me, it's not so much about the capability of the machines but rather if you have 3 phase supply and the space and lifting option when it comes to transformers.

If you have both, transformers every time, why? You get more for your money second hand.

 

[BrokenBiker]

if you can afford a new r tech than you should be able to find a decent old machine.

that said my mate has a very old and very reliable ac/dc tig and i have a new inverter with dc lift tig, and i prefer mine because i feel it is easier to weld with, however his tig is far superior to mine in every way.

there is nothing wrong with a new r tech, i have looked at their mig250 very extensively, and if they do go wrong r tech have very good support. If you buy a second hand machine and then 3 months down the like it goes pop you may find yourself looking for a new r tech anyway

 

[TheBrick]

Thanks for the replies. Space is an issue as it is for most people in the uk but I'm always draws to old industrial tools as I feel they should last. I need to have more of a think.

 

[ben8vgte]

I had a older FRO transformer/thyristor controlled tig and now have a r-tech, the transformer was 160A dc and needed 27 amps single phase at full wack the R tech needs 18A @200A output. Not too mention has a better duty cycle and I can pick it up and move it!

The R-tech is a far more useable machine by far, but the older one did the job and was a cheaper good start for me.

 

[daleyd]

I had a older FRO transformer/thyristor controlled tig and now have a r-tech, the transformer was 160A dc and needed 27 amps single phase at full wack the R tech needs 18A @200A output. Not too mention has a better duty cycle and I can pick it up and move it!

The R-tech is a far more useable machine by far, but the older one did the job and was a cheaper good start for me.

Blimey, I wouldn't have thought there would be that much difference between an older style and an inverter on the input! Goes to show how much things have moved on in electronic terms over the years.

 

[Bill Edwards]

It does make you wonder - aside from being better to use - how quickly would the reduced power consumption pay for the newer technology? It's not like electricity is free after all.

 

[TheBrick]

I had a older FRO transformer/thyristor controlled tig....

Wow I'm surprised at the difference too.

 

[shenion]

My old transformer TIG is now over 50 years old. Still keeps chugging along. These old beasts keep going and work well.

It does uses a lot of power. I have it on a 50A 240V circuit and it sometimes trips well under 200A. Only two balance control settings by changing internal wiring. No pulse, slope or frequency control. Not even thyristor controlled, only electronics in it are the diodes (some circuitry in the time-delay relay for post gas flow.)

Were talking 750 lbs and 4' tall (340 kilo).

I'd love to have a modern inverter machine for variable frequency and small size. But this was cheap and works. A modern machine that can match this in duty cycle would be very expensive (300A/60% duty, up to 475 amps out.) The modern machines look to be much better on thin metal with pulse and variable frequency AC.

The difference in cost of electricity is not a big issue unless you are doing production. The gas and consumables are far more of cost.

My MIG is basically a 400lb variac, no electronics either; 250A @ 100% duty cycle. Still plugging along after 35 years.

 

[zzr1200]

It all boils down to portability, transformers are heavier/larger than inverters but if your workshop based it doesn't matter.

If your looking at R Tech machines but like old style transformers with some controls, then maybe you should also be looking here , slightly more power hungry for the 220amp version, but british built.

There's more controls on the R Tech machine, but the comfort of owning a new old style transformer machine maybe worth considering.

Your in the position of ordering a cheap inverter machine from the Far East directly and forgoing any customer support, buying a Far East machine with support from the likes of R Tech or Portamig/TecArc and paying the extra premium for backup, or buying a new/old style transformer machine which should last for years.

Decisions decisions.....

If you would like 220 amps from a 16 amp supply you will have dig very deep to pay for it.....

 

[shenion]

I should mention, old TIG machines may need some work.

Mine had some connections and switches that needed cleaning. There was a blown resistor and the HF caps were bad. Parts can be found on ebay. I found the old vitreous enamel resistor and was able to make replacement caps off ebay parts.

Both were bad from the previous owner never doing periodic maintenance on the machine. Still I paid less than scrap value for the machine and $50 in parts. Now good for another 40 years

Power is better over here. I have a 150A service and that is considered less than normal these days; 200A is the norm now. So powering the beast is not a big issue. Then again, the manual says use a 175 amp breaker for full output at 240V I'm not building battleships in my garage so not a problem. If you find a Dialarc, Miller Syncrowave or other old beast cheap, expect to need 60 amp circuit to run it even at half power. Smaller machines will probably work on 32A. You won't get much on a 13 or 16A supply.

 

[TheBrick]

More good points shenion thanks.

Thanks for the link zzr1200

 

[Jim Davey]

I think the fan on an APB330 draws 8 amps!