HF add on boxes for AC tig work - how practical are they?

[Bill Edwards]

I've come across such an item in my home town.
It's an old Tec Arc box being sold with a 180a Pickhill oil cooled welder.

It appears to be very, very basic - 2T/4T, gas postflow and AC input giving AC output, with DC input to DC output also available.
How useful is it?
Like many, I'd like an AC tig, but it's more to have a play than anything that is likely to be really used much. This box doesn't make it possible to use a pedal, control the upslope or downslope, or even the AC balance.
Without these options, is an AC tig pretty limitied?

It's advertised for £300 which seems far too steep in my opinion. It probably works, but I don't know if it'll be practical to test it. The oil cooled welder has some value, but not much to me - I've an inverter which can do everything an oil cooled will. A torch and gas cylinder with an ancient regulator also seem to be included.

Can anybody help as to whether it's worth having or whether it's too limitied, and what sort of money would be sensible for the kit?

 

[Richard.]

It's usable I'd imagine but very limited. You'll lay something on a plate no problem but inside a fillet or across an outside corner could be more challenging. Without downslope or pedal craters could be an issue and very common on the ends of Alu beads. So you'll have to address that the old fashioned way of a re strike and dab. Balance again if it's fixed in a nice usable place then it's not too much of an issue as I tend not to alter mine too much. It is pricy though. Depends really on your plans. If you can get it cheap and get some arc time in to practice it then might pay you to buy a better machine later on.

 

[Richard.]

Bill. The biggest thing I think is important with ac Tig is arc stability. I'd suggest if it's possible you try it. If the arc is super stable then it's a usable machine. A lot of cheap modern inverters offer a serious Amount of scope and gadgets to attract us to buy it but when it comes down to the basic need I find some fail on that offering of a stable arc and all those bells and whistles don't matter any more. Look at it this way. People have been welding Alu for longer than I have been alive and although there are pluses to having better scopes on units it's not essential. Check the stability of the arc. If that's good then the rest you'll learn by going old school.

 

[Bill Edwards]

It'll be sat at 50 hertz I think, equal balance between neg and pos.

I'll try to speak to the seller and see if it's possible to try it. I'm not that sure I'll be able to though, it looks like he bought it from a chap who repaired motorbikes (I know who that person is, he did engine machining) and I don't think the person selling it has used it. However, it does have an argon bottle so if it's got some left it may be possible to strike an arc.
The only issue then though is me - although I can gas weld, I've never had a go at any TIG work and am probably not a great person to judge the stability of the arc - and if it's not great I probably won't know if it's the equipment, setup (e.g the right tungsten prep) or me.

 

[Richard.]

Your quite a trek otherwise I'd be happy to come along with you for a play. 50% balanced wave for one is gonna be hard work. A 1.6 tungsten up to and beyond 40 amps is gonna look like a lollipop.
If you can't try I'd never buy. It's worth viewing and having a play just incase it clicks and you Like it. Ask him to demonstrate it. If he can get a lovely run down then you can too.
With a machine like that go straight on with a 2.4 white tip. Little prep on it but not a sharp point as it's going to ball up quickly. A lump of 3mm Alu plate 100amps and wack it. Keep the arc tight don't bother with filler and just watch it. It should stay stable and controlled. If it starts wondering and flustering and spitting etc it's not you. Because at 100 amps it should be great. Take someone if you can that knows about it that always helps.

 

[hotrodder]

http://www.mig-welding.co.uk/forum/threads/first-go-at-tig.49891/#post-562844 While it's in a single box the Cebora Uno or whatever it's called that Pete bought is as basic as an AC buzz box with HF add on. Another mate of mine had a Miller Econo Twin HF which is even more basic (no gas solenoid) but had a lovely stable arc and was also capable of top quality work in the right hands

While nice to have things like slope control can be worked around. I doubt it'll ball up a tungsten to the extent that those of us used to more modern squarewave kit would expect... being sinewave the arc is (for want of a better word) soft and everything happens far more slowly than with an inverter as the waveform spends most of time transitioning between + and - rather than switching quickly and spending more time at the peak amperage. It's the thing that always catches me out initially when using ancient/basic kit

Oxy fuel experience is kinda both a blessing and a curse (mostly the former) in that while the movements and muscle memory are very similar arc length with TIG is shorter/more precise than with OA and controlling the heat by pulling the torch back a bit doesn't work with TIG. The later is the one i struggled with the most when initially learning TIG from a brazing/bronzewelding background. Now i mostly use TIG i find it a bit alien when going back to OA.
Obviously it's not the same as playing with different kit but you can see and hear the difference in arc stability towards the end of the vid in this post http://www.mig-welding.co.uk/forum/threads/ac-dc-tig-max-1500.50817/#post-578493 Yeah, he's using inverters with adjustable AC frequency and pulse etc. They don't make as much of a difference as sometimes claimed i.e. while cranking up the AC frequency for a fillet weld does narrow and stiffen the arc some it can and often will still dance around initially. That's the nature of ally and AC TIG

 

[wheresmejumper]

The biggest limilting factor i think would be the 5 amp increments of the Pickhill . Its more manageable at the higher range but will take a bit of skill to compensate on the light stuff

 

[Richard.]

http://www.mig-welding.co.uk/forum/threads/first-go-at-tig.49891/#post-562844 While it's in a single box the Cebora Uno or whatever it's called that Pete bought is as basic as an AC buzz box with HF add on. Another mate of mine had a Miller Econo Twin HF which is even more basic (no gas solenoid) but had a lovely stable arc and was also capable of top quality work in the right hands

While nice to have things like slope control can be worked around. I doubt it'll ball up a tungsten to the extent that those of us used to more modern squarewave kit would expect... being sinewave the arc is (for want of a better word) soft and everything happens far more slowly than with an inverter as the waveform spends most of time transitioning between + and - rather than switching quickly and spending more time at the peak amperage. It's the thing that always catches me out initially when using ancient/basic kit

Oxy fuel experience is kinda both a blessing and a curse (mostly the former) in that while the movements and muscle memory are very similar arc length with TIG is shorter/more precise than with OA and controlling the heat by pulling the torch back a bit doesn't work with TIG. The later is the one i struggled with the most when initially learning TIG from a brazing/bronzewelding background. Now i mostly use TIG i find it a bit alien when going back to OA.
Obviously it's not the same as playing with different kit but you can see and hear the difference in arc stability towards the end of the vid in this post http://www.mig-welding.co.uk/forum/threads/ac-dc-tig-max-1500.50817/#post-578493 Yeah, he's using inverters with adjustable AC frequency and pulse etc. They don't make as much of a difference as sometimes claimed i.e. while cranking up the AC frequency for a fillet weld does narrow and stiffen the arc some it can and often will still dance around initially. That's the nature of ally and AC TIG

I completely forgot about that box that Pete bought. Perfect example Of how basic equipment in the hands of a beginner can be good marriage. (With some excellent tuition of course )
Bill that thread is well worth a read as it shows how blinding results can be achieved with basic equip and limited confidence in the process.

 

[HughF]

They work well. But you will also need the capacitor bank unless your HF box has this included. I learnt on a boc christmas tree set powered by a 200a English electric oil cooled machine.

 

[Bill Edwards]

If I end up picking up ali tig as well as Pete I'd be a happy chap!

It looks then like it's potentially well worth having, I'll get in touch with the seller as soon as I'm able.
If it fires up and has a stable arc, what sort of money would be appropriate to hand over for it?

 

[Richard.]

Ah. I knew that was coming next. I've no idea of the value of them at all. Because it's old it's new price way back then would have zero reflection on it's value today. Google some similar set ups that are selling and if it's cheap in comparison keep quiet if not voice up. I'd guess £300 is quite dear really but that is a big guess based on what you get and how sought after they are. (Inverters seem to be the weapon of choice these days)

 

[HughF]

30 quid more like. Given the cost of a Newark viper 2500s second hand. Granted I know the viper doesn't do ac, but they're capable machines doing a similar job.

If you want an hf add-on box, I've got a spare Union carbide one that needs slight attention you can have for the cost of shipping. The hf wasn't particularly strong last time I tried to use it (10 years ago)...

 

[HughF]

Send us some of those nu5 rods in exchange and I'll cover the shipping Bill...

 

[AndyStobbs]

Would be good if someone came up with an intermediate box that would chop up DC into AC sq wave. So an exist DC tig could be used as a modern AC set.

 

[Bill Edwards]

Hugh, what's needed for your Union carbide box, is it usable (or if not, can an electrical numpty like me fix it) and what is/was it like to weld with, if your memory goes back that far in detail - I know mine doesn't!

 

[HughF]

Contactor works, gas solenoid works, hf was temperamental, you need a buzz box to go with it, or other ac power source. It doesn't have dinse connectors so you need to connect it up with ring terminals. It's old and might be no use, but it's kicking around here and you're welcome to it. I think the contactor is rated to 100amps but that is probably conservative.

I'll try and fire it up to see if the hf is doing anything.

 

[Richard.]

Worth a punt I would say. What's the worst that can happen. It doesn't work and your a handful of nu5 celulosics lighter.

 

[HughF]

Okay, I've dug this out. It's hurt to the point where it really is only fit for scrap. Powered it up, the contactor buzzes and rust dust comes out, the hf is dead. Inside the hermetically sealed hf unit it is all immaculate with a high voltage transformer, a high voltage capacitor and a few other discrete components. Looks like something from a 1950's x-Ray machine

Sorry about that Bill...

 

[Bill Edwards]

No worries, thanks for looking. If it was OK we could have happily done a swap, but things don't always work out as we'd like.

 

[HughF]

200 quid for the pick hill and the hf box is probably reasonable I would think.