I have a Torchmate 4X4 table with a Hypertherm powermax 85 amp machine.

I am trying to cut 6mm steel. The steel is new. The Kobe steel plant is just down the road a bit. So super clean, no rust.

On the advice of Jim Colt I have played with the machine to the point that I was happy with the cut and the amount of dross primarily on 3mm or less steel.

I am now moving up to 6mm steel. And the projects are getting more complex and I am having some issues with fitting things up.

I did my initial cuts using 85 amps and 85 amp consumables. I used the recommended speed, voltage, pierce height and cut height.

initially, expecting great results I laid out a full 1200mm X 1200mm sheet to cut.

The results were somewhat disappointing. The parts would not fit together due to excess taper on the cuts.

So I had a lot of work with a file to get things to interlock the way they should. Not fun.

I checked the table for square and was satisfied with the results.

On Jim's recommendation I do use an antispatter spray on all cutting operations.

I then ran a speed test and selected the speed with the least dross. And tried again on the smallest set of parts. Dross was reduced but that was not the major issue. Taper was still to high and when cutting in the corners definition was still lost.

I then set about trying to get the best cut definition and least taper I could.

I installed a fresh set of 45 amp consumables and tested speed variations.

I started at 50ipm (inches per minute) 137volts.

I reduced the speed by 5ipm increments all the way down to 20ipm, By this point the parts were fitting together but the taper was still not as good as I wanted.

After reading this article:

http://www.lindecanada.com/internet....2185.pdf?v=1.0

I selected 25ipm and held that steady and tried to adjust the voltage. It soon became apparent that reducing the voltage would result in the torch moving into contact with the material. I then tried increasing the voltage in 1volt steps. This did not seem to have much effect on the taper angle. I am reluctant to play with the voltage too much as it is unclear to me what the limits on this are.

I then held the consumables at 45 amps and Voltage steady and started cutting the smallest sets with variation in the amperage. I ran the amps up in 5 amp increments.

I am now using 55A, 25ipm, 137v and 45 amp consumables. Judging by the recommended settings in the hypertherm manual the voltage is too high. For 45Amps they recommend 137v and for 65Amps they suggest 127v. But this does not seem to be a linear relationship. And with only three data points fitting a curve to it may just lead me in the wrong direction.

I would still like to improve on this. But I am not sure how many more sheets of steel I want to invest in this process to dial this in.

Would the collective wisdom be to slow down the cutting even more? Should I try the 65 amp consumables and start all over again? How much variation in voltage is thought to be productive? Is the voltage a function of the machine amp setting or the consumable amperage?

I think what I am asking is how do I stretch out the plasma cone more. What setting does that. And would I be better off cutting at a higher amperage and playing with the speed more?