Originally Posted by
matttargett4
Hi Guys,
Ive never really done much mechanised oxy fuel cutting before this week but my plasma has failed and ive been using the gas to make up for it and ive found a few things id like to ask about.
My torch is a 3 hose harris machine torch and i have a solenoid on the cut oxygen, im using vvc nozzles, i only have a 1/2 and 1 to hand at the moment.
I have my fuel (propane) pressure regulated at the bottle, my oxgen regulated to the cut pressure at the bottle and the preheat pressure is regulated on the machine.
When i set the pressures to those specified in the cut charts i was imagining turn all three taps full on would produce a cutting flame but it seems way rich on fuel so my first question is, how do i set the correct cutting flame?
Second, how high from the material for preheat, pierce and cut?
How do pro's know how long to preheat for? Clearly too long melts your part, too short no penetration, i also find it makes a considerable difference where the pierce is and how many pierces have already been made in the plate, can i account for this in any way?
Clearly the nozzles are made for a material thickness but like i said i have only big nozzles on hand and the thickest ive cut is 15mm, cut quality was pretty good but can i turn the gas down and use them sensibly on thinner material? I have foud when going down as thin as 8mm that i cant really increase the cut speed above the max speed in the chart even though the material is half the thickness of that in the chart.
How many people here are using water tables? I have one for the plamsa but its empty just now but i seem to get lots of warping, is that just because i need a smaller nozzle or is there something i need to do to work round it?
I ordered some smaller nozzles from the grand old us of a with my hypertherm plasma parts, they are much cheaper and i figured i had to pay one lot of shipping, trouble is the plasma parts are on back order so my angle grinder is taking a pounding!!
Matt