I bought an unfinished plasma table with an Esab ESP-50 and MP1000 THC. It took me a bit to get it running and was always having problems with loosing the Arc. I was told that it was probably too much moisture in the lines. I bought a motor guard filter for it, and that didn't seem to make a difference. So, I bought a refrigerated air dryer and hooked that inline after the motor guard, plus I have a water trap directly on the air compressor and after the air dryer.
I have extremely clean dry air now... but the problem just keeps getting worse.
Tonight I spent a few hours in the shop playing with it and trying to confirm
what is happening. I made a part file that is scripted lettering and an couple
of names and about 6" X 8"
When I first started cutting it the holes in the lettering dropped out just
fine, and then it proceeded to cut the outside of the lettering in one constant
path. The torch cut for about twelve inches the first time then lost the arc,
paused shortly after and refired and continued. Then it would only go 6 inches
and loose the arc and would continually get worse. The relay on the THC sensor card was turning the ESP-50 off, then refiring it. As the project continued the torch would only just fire, then shut off again.
I put my hand on top of the MP1000 and noticed that it was a bit warm. I had initially thought that I may have had a noise problem, but after messing with it tonight I am pretty sure that something is getting warm in the MP1000 and turning off the relay signal.
Is there anything I should be looking at in the MP1000? Has anyone else had any issues similar to this?
Can you tell if the torch goes out as a result of the torch-to-workpiece distance getting too high? If so, the THC may be the problem. If you have a flat workpiece and a level table, you could disable the THC and run with THC off to verify that it is the problem. If THC is doing its job, you may have the trouble in your plasma power supply.
I'm following this thread closely to see if you get this resolved. I have a similar problem. I never considered noise though. We have a big exhaust fan running near the controller. I'm going to run the table with that off to see if it helps.
The THC seems to be functioning great as far as keeping the torch at the correct height. But I am pretty sure that a component is overheating. So, next time I have a chance I will pull the cover off the THC box (maybe even put a fan on it) run the torch and note any improvement. I will also make sure to get a bunch of pictures so Tom will have an idea of what revision I have on the boards.
If I don't see an improvement I will look for a relay around the shop to wire to the torch trigger and see how the machine runs without the THC all together. I hate the idea of running without the THC, but if thats what it takes to be able to knock out some projects it will have to do. I have about ten good projects to do and everyone is waiting on me to get this thing working.
I finally got a chance to work on it again last night.
I pulled the cover off the MP1000, nothing looked amiss in there and none of the components were getting warm. It was also pretty clean. I also added a backup power supply to the computer, then to the computer and MP1000. Nothing helped. The diagnostic light in Mach3 says the torch output is staying ON, and the torch on light on the front panel of the MP1000 is staying on. The relay on the torch sensor board is still kicking off randomly, only when the ESAB is running. If I run a gcode with the esab off the relay works as it should.
The only thing I can think to try now is to swap out the serial cable going from the sensor card to the MP1000.
Anyone have any ideas?
Another thing to note. The table had been working much better and has gotten progressively worse. I was able to cut 20 parts in a row, 19 good ones then on the 20th I would have a flame out. Then after about 5 min of reorganizing materials and toolpaths I would be able to cut about ten parts before the problems would start happening. Now its down to cutting about 4" before the torch gets kicked off.
Is there a duty cycle to consider for the plasma cutter? You cut 20 parts, then the machine messed up. Did some component cool down enough, but not quite cool enough then you were able to only get 10 parts?
I don't have an answer. Just critical thinking.
i have an Esab ESP-50, I believe it is a 100% duty cycle machine. The machine has never run for more than a minute or two at a time. The touch down and start cycle takes about 20 seconds.
I just tried swapping the serial cable and it didn't make a difference. So I pulled the hole thing off the machine. I will be going through my bins and rounding up a relay and some connectors. Then I will at least be able to cut something.
Tom from candcnc got back to me on the candcnc yahoo support forum and said:
"ESAB machines are rough on Sensor cards. I don't know about the smaller units but the 850 and up used to eat the REV 9 and REV 12 cards for lunch. The ESAB uses a CD (capacitor discharge) arc start that puts thousands of volts (like a spark plug) to start the arc. We put in extra suppression (including a mechanical arc gap) on the REV 14 card specifically to work with the CD start units.
There is a new ZIP file in the SheetCAM Posts folder on the Files section that
has all of the POSTS for both 1000 and 3000 units. There is no difference but
in the name. There is a 1000 based post named "Dual Relay" in the title. Read
the readme.txt file out of the zip and use one of the aux relays on the Table
I/O (the one that fires with an M07 command) as the TORCH Relay. Just move the two wires that fire the torch over to that relay. That bypasses the torch relay on the sensor card.
In short the problem is a ground loop but they can be hard to find. It obvious
that the Relay signal is there all the time and that it is an interaction
between the ESAB and the THC Sensor card Torch Relay circuit. It's probably an AC voltage getting onto the THC ground side and causing the +12 on the Torch relay to do ON/OFF.
If you have tried all of the other things I suggested then the separate relay is
the only other solution. The THC Sensor card MAY have been damaged."
My system comes from before they had relays on the I/O card. I have asked if they will warranty or exchange those two boards, and I will wait to do anything until I hear from him.
Just a thought...what kind of dedicated grounding system have you installed? what is the ground test? When you run a plasma, there is a great amount of RF Noise. This noise will play havoc on your electrical components, especially the start signal and the encoders on the drive system. With plasama, you should be less than one OHM on your grounding. This is not a Power ground. This is an independant ground system. After you achieve the 1 Ohm, you will need a chasis ground from the plasma power supply, one from the machine gantry, and one from the table all going to the first dedicated ground rod. Additional ground rods should be ran in series with the first ground rod at a distance of 1.1 times the depth of the rod installed. This soulds like a noise issue at first glance.
Tried the new sensor card and it didn't make a difference. I wired in another relay and used the M07/M09 to turn it on and off. Now the torch works just fine... but the THC is all over the place, at first it wasn't doing anything. Then I tried enabled the output 1 (Torch on) and them the THC was working but isn't tracking at all. Volts go from 99 to 138 and it just isn't following a pattern.
I am just about ready to chain the whole works to the back of my truck and just drive down some curvy roads real fast until the damn thing isn't there anymore.