hf/scratch start difference

[bawjaws]

so im thinking about getting an inverter dc arc/tig shortly after christmas, possibly one of the iverter fusing things, ive never tigged in my life so could one of you nice people please tell me the difference between hf and scratch start tig, i have a rough idea but i dont know if im right

 

[Archie]

Scratch start you need to touch the tungsten onto the workpiece to initiate an arc. HF start you just hold the torch above the workpiece and press go, either on the foot pedal or on the torch.

 

[Paul.]

With scratch start you need to touch down the electrode or scratch it on the job then withdraw to make your arc gap, like striking an ma electrode, A HF start will initiate the arc for you without touching down, much kinder to the electrode, and less risk of contamination

 

[bawjaws]

ahh just what i thought then, but does it make any difference to the actual weld? thanks

 

[Paul.]

not really but your start may be more untidy until you get the hang of it, I use a scratch start a lot on site, with perfectly acceptable results, youll be grinding tips more often too

 

[Archie]

I would have thought the weld would only be affected if by scratch starting you contaminated the tungsten.

 

[irondarren]

Baw the difference is Hf start produce a hig frequency arc, which will jump from torch to work piece, and begin a welding arc. Scratch start is kind of like arc welding, where you have to make contain with the work piece and then lift off a little, this then begins the welding arc.
The main advantage of HF start is that there is no contact involve hence you wont damage your nicely ground tungsten tip.
Hf units normally have the plug for a foot pedal which is a nice little extra at around £250
Lorch 180amp tig welder unit
The lorch unit shows the capability of remote control as is http://www.inverterfusion.com/ the fusion unit. Hf is going to cost more money, but if your budget will go that far go for it. Weldequip will no doubt do a good deal for you anyway, and i believe he can do you either a fusion unit or a lorch unit now

 

[bawjaws]

thanks folks - you all know too much im not looking to buy one in the next 10 minutes or anything im just browsing at the moment, also it wouldent be often that i done tig, it,d just be gid to try, im more after a decent arc unit

 

[irondarren]

Baw if its mostly arc, i would say a good quality scratch start would be fine, you will pay a fair bit more for the hf option. im sure in another thread someone said they got a lorch h150 for about £400, the fusion 160ma is cheap but has only 56v ocv, the fusion 180ma is around the £400 mark and similar in spec to the lorch, th hf fusion 180 unit is over £600 so there is a big difference in price

 

[bawjaws]

ye i reckon when i gather the money ill probably go for an invertor fusion or a lorch

 

[shenion]

There is also "Lift-start" and "touch-start". One I think is an trademark. Basically it sets the unit to a lower voltage/current until you establish an arc. That helps prevent contaminating the tungsten.

you might check if some of the non-HF units have a similar feature.

 

[Paul.]

Here you go Bawjaws, have a look at this.

 

[bawjaws]

nice one paul

 

[Shox Dr]

If I had to buy another set and I had to choose between Lift, Scratch and HF I would have Lift Start.
I like LS for flash tacking up, on very thin material (<23g) as you can sit the tungsten down press the button and lift, as soon as its off the work piece its alight and you have a very small tack, with no fear of the metal dissappearing.

 

[Rick]

Biggest problem with scratch starting is stopping IMO. Other than that perfectly acceptable.

 

[Mikey D]

with scratch start you have to contol the gas flow manually too , no slope down or post gas controls which you will have with a hf machine

i started off using a scratch start machine and it was fine to learn with ,

have a nice IFL 200hf machine now

cheers mike

 

[Shox Dr]

Not all scratch start machines have live torches, the ones that do tend to be site machines, that are very basic, so they last longer.

A mate of mine has a S/start set and it is trigger activated, with pre/ post gas, slope etc etc

 

[Paul.]

Not all scratch start machines have live torches, the ones that do tend to be site machines, that are very basic, so they last longer.

A mate of mine has a S/start set and it is trigger activated, with pre/ post gas, slope etc etc

Its probably a lift arc set rather than a basic scratch start machine then.

 

[Shox Dr]

Noop, it's an ebay jobby, it was advertised as HF, but it's S/start. I know I've used it. I told him to send it back but he wont