is this a pm45 problem??

[f_armer]

I put together a Bulltear Gantry kit, everything is working exactly as it should, except for the THC. Well the THC seems to be I working, but for example cutting 10 gauge my preset volts should be 117, but when I make test cuts, with the THC OFF, the torch volts read anywhere from 45-90, they jump all over but average 55-75. So, when my preset is 117 and the THC is ON the torch just raises up well over an inch until the torch cuts out.
The indicators are telling it to go up, so the THC is working.
If I enter 63 volts as my preset, the THC does move up and down during the cut, but it's not pretty, because the voltage seems to fluctuate so much, it'll start out around 80-90, then drops to 45-55 then comes up around 60-70. I don't think the THC can keep up with it.
Havent had any experience with this before, should the voltage be that far off, and how much should it fluctuate??
I have a new Hypertherm PM45, with built in voltage divider preset to 50:1, with a new machine torch, with new consumables. The PWM module is set at 50:1, when I push the test button on the PWM my voltage in Mach reads 125-6, when I push the test button on the box, it reads 100, then 150, and flashes the up, and down led's.
In Sheetcam I am using MP3000-DTHCII+scriber2 as my post processor.
I loaded BladerunnerAIO DTHCII Plasma into Mach from the MasterInstaller file on the website.
The control box is a CandCNC ESP II Bladerunner.
I have my ground clamp directly on my work piece.
It cuts good with the THC turned off, the cuts are fast, accurate, and to scale. Could this be a problem with the PM45 not putting out the proper voltage reading?
Is there a way to test if the PM45 is working properly?
It will make a skip once in a while, where the tip cuts out then back on leaving about a 1" uncut portion. The arc ok lights in Mach blinks off when this happens.
Sorry if the post is a bit jumbled. I just got the table put together 3 days ago, made it move around and first cuts 2 days ago, so i'm pretty new at this.
If more info is needed please let me know, i really want to get this sorted out.
Bulltear has been really good to help, but I just thought I'd get my problem out to a bigger audience, to see if that helps.
Thanks to anyone who has suggestions.

[f_armer]

Update....A friend of mine had a PM45 that I borrowed and tried it on my table. The results were exactly the same, THC just fluctuates all over and ends up raising too high until the torch goes out.

[jimcolt]

You can read the actual arc voltage on the raw arc voltage terminals inside the Powermax45 power supply. This voltage is the actual measurement between the torch electrode and the work ground cable. Arc voltage is a function of the length of the arc....longer arc, higher voltsge. It is physically impossible for the arc voltage to be able to maintain a cutting arc at voltages below about 70 volts.....so you clearly have some sort of calibration or wiring issue with your height control system. The arc voltages listed in the Hypoertherm manual are correct, this assumes you are running at the amperage listed, as well as the physical cut height (measured with a feeler gauge) and the speed listed.....so if you are cutting under these conditions and measure the raw arc voltage off the board it will be the same as the reading listed in the manual.


Jim Colt Hypertherm

[f_armer]

I am running at 45amps and all my settings are by the book. If I stop it mid cut with thc off the nozzle is very close to .06 off the metal.
What I found interesting from your post is that its impossible to make arc below 70v, it makes it very obvious that something else is wrong.
Thanks for the reply

[f_armer]

I think I've found the issue, I tested the voltage coming out of the cpc plug on the plasma, it was around 3.4v which apparently is correct, for firing the torch in the air. When I test the other end of the short cord from the cpc to the pwm for height control I only get 2.7v so somewhere in a 1 foot long cord I am losing voltage.
New cord is on the way.