[Peepers]

This is my first post and a somewhat desperate one.
I built my plasma table about a year ago and have been very luck to have had no real problems until last week. I cut art stuff from 16 ga steel.
My setup consist of Mach 3, SheetCam, THC300, and a Hypertherm Powermax 1000. I cut 16 ga steel using Finecut consumables at 250 IPM, .13 pierce height, .065 cut height, around 32 amps and 85 psi air pressure. My tip voltage is around 48 volts but is only good for my reference as the THC meter is not calibrated correctly.
These settings are the result of a lot of testing and have produced very clean
and slag/dross free cuts.
I know the manual says .08 cut height and 150 IPM at 40 amps but I found I got much cleaner cuts at my own settings.

The problem I have now occurred after I cut 10 or 12 nested pieces which cut perfectly. I loaded another file of nested parts all from the same post processor setup. I indexed to my start point on same sheet of steel and started the process. The torch has no problem piercing and the cut starts. Randomly the arc will bounce up form the steel and not cut this may happen for an inch or two or it may five or six and then continue to cut fine for a while and then do the same thing not cutting through.
It does not matter whether the THC is on or off or if it is a straight cut or a curve. I have tried slowing down cut speed, increasing current, changed consumables, just about everything I can think of and nothing has worked.
I have not been able to figure out if it is the plasma cutter or what.
Any ideas or suggestions will be appreciated.

[CNCCajun]

This is my first post and a somewhat desperate one.
I built my plasma table about a year ago and have been very luck to have had no real problems until last week. I cut art stuff from 16 ga steel.
My setup consist of Mach 3, SheetCam, THC300, and a Hypertherm Powermax 1000. I cut 16 ga steel using Finecut consumables at 250 IPM, .13 pierce height, .065 cut height, around 32 amps and 85 psi air pressure. My tip voltage is around 48 volts but is only good for my reference as the THC meter is not calibrated correctly.
These settings are the result of a lot of testing and have produced very clean
and slag/dross free cuts.
I know the manual says .08 cut height and 150 IPM at 40 amps but I found I got much cleaner cuts at my own settings.

The problem I have now occurred after I cut 10 or 12 nested pieces which cut perfectly. I loaded another file of nested parts all from the same post processor setup. I indexed to my start point on same sheet of steel and started the process. The torch has no problem piercing and the cut starts. Randomly the arc will bounce up form the steel and not cut this may happen for an inch or two or it may five or six and then continue to cut fine for a while and then do the same thing not cutting through.
It does not matter whether the THC is on or off or if it is a straight cut or a curve. I have tried slowing down cut speed, increasing current, changed consumables, just about everything I can think of and nothing has worked.
I have not been able to figure out if it is the plasma cutter or what.
Any ideas or suggestions will be appreciated.

Well, I surely do not "KNOW" . . . . but as an instrument tech I have found that the one step that you take for granted is usually the "gremlin" that you chase for hours . . . My "GUESS" . . . it's a grounding issue . . .

Will follow thread to learn from the truly knowledgeable that are on this forum . . .

[Plasma_Tech]

Peepers

Your PMX1000 has a silver switch by the current knob - this is the plasma mode switch. What it sounds like is you have this in the "UP" position which will go back to a "pilot arc" when the transferred arc is lost ... possibly because of the speed you are traveling at?

I would keep the switch in the middle position and verify the arc is going out.

Some possible issues - Traveling too fast for the arc to stay attached, Your pierce time is too long and it ran out of material for the arc to stay attached to. Or a bad connection with the work clamp from the cutter.

Keep us posted?

Jake

[jimcolt]

The most common problem that causes an apparent loss of cutting power in the middle of a cut with an air plasma is moisture in your air. Moisture often comes through the air lines as intermittent slugs.....and when you think about what is going on inside the torch (ionization of air.....then applying DC power to the conductive ionized air stream)....water completely changes the internal physics that produce the plasma arc.

Make sure your compressor tank is drained....more often during humid months (summer)....and install adequate dryers if you determine moisture is a problem. A refrigerated air dryer is the best solution (Harbor Freight has one that reportedly works very well in the $350 range).....desicant dryers work well......and there are filters such as Motor Guard that also work well but the elements must be changed fairly often in humid conditions.

If you talk with tech service guys at the major Plasma companies (Hypertherm)....they will tell you that the number of calls they get with your exact symptoms always rises during the summer months...


Jim Colt

[cowleym]

Yep
Jims explanation sounds good, I would usually get the customer to switch the plasma to gas test (I think you turn the current knob fully ACW on a powermax) and place a sheet of white paper under the torch fo a few mins. Observe - if its damp or shows any sign of moisture (spots) sort out the air.

mike


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