Wildly varying angularity on 1"

[Shane Warnick]

So, I cut some parts today for an equipment company, from some 1" mild steel bar. I cut parts from the same bar last week, everything was straight as an arrow, no issues. Today, when I cut these pieces, the angularity along one side (not the same side nor the same axis on any of them) looks horrible, and varies wildly. ONLY on the one side. WHAT THE HELL says me????? It almost looks like a snake undulating along. Here is the kicker. When I cut the drop off, the cut is dead nuts straight. No variance at all. Powermax 85, 85 amps, shielded, cut height 0.60, edge start, 9 ipm on speed. New nozzle, new shield, new electrode, same swirl ring as last week. Air pressure was stable, I was watching the gauge after the first one cut. Air is dry, refrig air dryer running, new desiccant last Tuesday, indicator still blue. Ground was on and good like normal, grounded to the flat bar. The parts are basically a right triangle, with the short sides being 3" and 5.25". Again, on some of them its along the 3" axis, some the 5" axis, and one, down the long axis (hypotenuse) where the angularity is a problem, and varies as well.


Thoughts?????

Pictures below.

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2015-12-11 14.23.38.pdf

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2015-12-11 14.23.28.pdf

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2015-12-11 14.23.01.pdf

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Thanks in advance for your time on this.

Shane

[BTA Plasma]

Still looks like moisture

[Brand X]

I think it's the name of the game with the smaller 1/3 phase plasma cutters.. You can cut thicker then 1 inch, and get good parts, just not every time. O/A, or O/P will give you more consistence MS parts over the long haul.. This is mostly coming from my friend that cuts tons of decent thicknesses with his Thermal 151, and Powermax 85, and Esab 1125.. I found the same thing with my Victor A-120, and Esab 1600..
I believe you need the next level of machine up or stick with a gas axe.. (IMO) They do much nicer on 2 inch also..


You speed seems a bit slow too.. I found 12 to 13 ipm with the 85 Hypertherm/90 amp Esab/ 100 amp with the Thermal power

[jimcolt]

I can pretty much guarantee that you have a damaged nozzle orifice or shield...or both. You cannot possibly get that bad of an angle without consumable issues. The swirl ring and retaining cap also control air flow, which affects angularity.....though usually not to that level. A small nick in the nozzle orifice (inspect with a 10X magnifier), same in the shield orifice.....or evidence of arcing between the shield and the nozzle are indicators of incorrect edge start. Edge starting should be done with the nozzle orifice centered on the edge and with similar pierce delay that you would use for piercing....if this is not done correctly the orifice can be damaged on the first start.
Close up pics of the inside and outside of shield and nozzle will help.

Jim Colt Hypertherm