Random loss of arc while cutting

[Metalfab77]

Looking for some help trouble shooting this problem. I am running mach3,sheetcam on a Precision Plasma 4x8 Patriot with a Power max 85. It happens on all gauges of steel randomly on small cuts and in the middle of long straight cuts. The numbers on the screen look good with in 1 to 2 volts. I drain the compressor daily but do not have a drier system could it be moisture in the line. I am grounded to the Material. I have tried all new consumables. Thanks

[beefy]

Look at this thread. I posted yesterday about narrowing down what is turning the arc off. Not the whole solution but good to eliminate what is NOT a problem.

http://www.plasmaspider.com/viewtopic.php?f=4&t=10739

Keith.

[Metalfab77]

Thanks I will try that. Right now I will try anything. Hoping to be able to cut in the a.m. and see if that helps.

[Metalfab77]

I been doing some cuts this morning and I read your link. I checked my cut profile and I have it on THC auto on checked.
While cutting the lights on the voltage card do go out when I lose arc. I watched the power supply readout on the bottom right on the mach 3 screen and my volts read 47 and amps read 2 or 3 constant. I lose arc for a split second and then it comes back and continues to keep cutting.

[BTA Plasma]

That is usually a sign of a PC failing if it hadnt happened before.

[beefy]

Metalfab,

in the cut profiles it was "torch off on arc loss" not "auto THC on" that I mentioned (although having auto THC on won't hurt).

The bottom right of your screen is the Candcnc power supply, not the plasma amps. If you haven't got the Candcnc digital current probe on your system then you'd have to get hold of a DC clamp meter and put it over the ground lead of the plasma cutter to measure plasma amps.

Anyway you think it's the actual signal from the computer which is turning off, and causing your torch to switch off. As BTA Plasma said the PC could possibly be going wonky.

On the software side of things Mach requires the following:

XP in installed in "Standard PC Mode" - go to Device Manager in Control Panel and look under "Computer". Does it say "Standard PC".

Has the Mach XP optimisation procedure been done - found a link: https://www.probotix.com/downloads/XP_Optimization.txt

There's nothing else running on your computer. Windows is a mulitasking system and shares it's resources with other programs. I might go overboard but I've even went as far as disabling XP processes that I think should have nothing to do with running Mach, things like printing, wireless and networking.

Have you tried the Mach driver test. In the main Mach folder there's a file called "DriverTest.exe". I keep a shortcut on my desktop and periodically run it. I don't understand a lot of the info there but I want a nice straight line with no serious spikes on it. I always test mine right up to 100 Khz.

Keith.

[Metalfab77]

Been having this problem for awhile. Are you thinking complete reboot or bad tower. I just run Mach3 on the one conected to the table no internet connection and had it wiped before I hooked it up. I do have a backup tower if you think that might be the problem.

[Metalfab77]

Beefy,

The THC is the only one checked. As far as the up dating I have not tried that it is an XP but may need to update the hardware. I will try what you recommended in the morning if I can otherwise Monday morning. I am asuming I will have to be connected to the internet or do you think I can download them on a them drive and install thru usb.

[beefy]

Hi Metalfab,

when you say you assume you need to be connected to the internet, do you mean with your cnc computer ??

If you do then no, you should be using another computer for any online stuff. Think of your cnc computer as nothing but a controller for your table. You don't want to be doing anything else with it. Transfer any files via USB stick, etc.

You are not updating anything.

I'm not saying go and do this, just trying to give you an understanding of how I setup my computer. If you ever want to start doing something like the following, double check with Tom from Candcnc. I've done this many times and it's easy for me now but it was slow in the beginning.

Here's a runthrough of my typical installation on a new computer:
Bootup with XP install CD
Install in Standard PC mode
Delete existing partition
Create new partition
Install XP on new partition (prompts for full or quick hard drive format).

Install motherboard drivers (mainly chipset & video, I don't bother with sound or network drivers)

Go through XP optimisation

Install Mach / Candcnc system as per the manual

At no time am I "updating" anything, or connected to the internet. Everything is done with the XP install CD plus a USB stick that carries the motherboard drivers and the Candcnc/Mach install files.

Hopefully you have XP running in Standard PC mode already.

Keith.

[Metalfab77]

I was able to spend time at the shop and have done a few things. My computer was on ACPI uniprocessor so I switched it to Standard PC. I ran the Driver test and I do have some small spikes through out and have a spike that goes to the very top. The more read the more I believe that it is on the computer side. I can cut a line 8 ft long by controlling it manually and have no problems.

[Metalfab77]

When I installed Mach it was in ACPI Uniprocessor not standard. I have switched it to standard do I need to reinstall or will it recognice the change. I don't know if this will help but when the torch goes out the torch light is still on and also so is the run. I never have a fault code when it does happen. Thanks

[beefy]

Hi Metalfab,

I have absolutely no idea if just changing to "Standard PC" is the same as completely re-installing XP in Standard PC mode, I'd like to know that myself. Perhaps Tom at Candcnc or the Machsupport forum would know that.

So you say the torch on light is staying on when the torch goes off. This problem seems to be similar to the other thread (the one I linked to). Shoot over to that thread again and see my latest suggestions on that.

Regarding the Mach driver test. I don't think it's a good thing at all if you get even one big spike on that line. Purely guesswork here but maybe that's enough to throw a spanner in the works while things are going smoothly. Mach has to keep quite tight control of everything and if Windows manages to "get a word in edgeways" then Mach just might lose focuss for a breif moment. Maybe another question for Tom or Machsupport.

What I have noticed with nearly every driver test is there is an initial "settling in" period then the line goes flat and is normally good from that point.

Keith.

[Metalfab77]

so I got a different tower the other day had it wiped to try and see if I have the same problem. I installed mach and ran a few things and my torch head is slow to re act. I know at one time I had this problem it was a setting some where but can not remember which one. Could it be THC Rate on the settings page

[Metalfab77]

Hooked up new tower. I am hoping I did not waste any ones time but I have the same problem and I think I did not ground everythig correct. Can anyone give me a rough diagrahm of how yhey earth ground there setup. I am going to post this also on the general


Thanks
Guy that does not under stand elec

[cnchybrid]

10' ground rode at home depot or lowes.
Drill through concrete close to the machine... 6 inches or so
Drive ground rode into ground leaving about 3 Inches above the ground.
Attach a ground clamp with a 2 guage ground wire running from that ground clamp to the machine next to the ground rode.
Attach a brass Star Ground to your machine leg.
Attach all the other grounds to that start ground.
Cross your fingers.