2t/4t tig trigger ????

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can someone please explain the differences between 2t/4t....??was using a machine (Kempii Mastertig 3500) awhile back, on a job...great machine by the way.  Was welding 1/4" aluminum fillets....seemed that the pedal was only acting as an on/off switch not modulating the current like I wanted it to....or expected it to.  Anyhow, got the job done alright and moved on....but its been bothering me ever since.  Didn't have much of a chance to "play" with this machine and see if I could get it to work properly.  I'm now thinking that it was some kind of incorrect setting of the 2t/4t business.  My question is basically: what the hell is 2t/4t?  Also....this pedal had a small pot on the back of it....wondering if anybody knows what thats for?Thanks,Chris
Reply:Originally Posted by wmb97can someone please explain the differences between 2t/4t....??was using a machine (Kempii Mastertig 3500) awhile back, on a job...great machine by the way.  Was welding 1/4" aluminum fillets....seemed that the pedal was only acting as an on/off switch not modulating the current like I wanted it to....or expected it to.  Anyhow, got the job done alright and moved on....but its been bothering me ever since.  Didn't have much of a chance to "play" with this machine and see if I could get it to work properly.  I'm now thinking that it was some kind of incorrect setting of the 2t/4t business.  My question is basically: what the hell is 2t/4t?  Also....this pedal had a small pot on the back of it....wondering if anybody knows what thats for?Thanks,Chris
Reply:the 2T and 4T ramp up/down and hold the current preset. The remot becomes an on off as you note.  The idea is to let the sequencer do the typical work and the pulse do the modulation. The ramp down takes care of the crater fill. There are variations on the machines so you should  look at your units manual if you can. Once you start using the trigger,  (I use 2T) , you will like it and you can then replace your pedal with a simple on off switch on the torch. Great for out of position work
Reply:cluna is correct. Check the panel to see if there is an amperage control switch. If so, and if it is set to panel, the setting on the machine is what you are going to get. If it is set to remote, the pedal acts as a control device, raising and lowering the amperage as needed. If using 2T, set the amperage switch to remote.Hope this helps.Tony
Reply:The difference between 2T, 4T and using the pedal is that the pedal gives you continuous amperage control from zero to full current ( what you have set to max ) where 2T and 4T are stepped, triggered mode where a contact switch initiates a series of pre programmed current settings in sequence.For example, with 2T, you press the contactor and the current will ramp up, on a slope, to the max current and stay there until you hit the contactor again and the current will then ramp down to zero. 4T is a four stepped sequence.
Reply:Ooops, sorry, I didn't read cluna's post which explains it already.
Reply:Originally Posted by RC-RacerOoops, sorry, I didn't read cluna's post which explains it already.