Problems shorting out boards in control system, help???

[tacoma747]

Running Mach 3 software, the control box is from Probotix. The boards that keep popping are in the link below. http://www.probotix.com/stepper_motor_d ... ProboStep/

It has been popping the Y-Axis board mostly, two times when I first got the table as soon as I would try to make a cut replaced the board), then after talking to the manufacturer, they told me to make sure the ground rod going to the grating on the table was attached well, now, so then I attached the ground rod directly to the material I was cutting (with the plasma ground clamp), that seemed to work, I was able to cut a few things out. Now today I was cutting and it blew the Y-axis board again. After swapping the board out, it worked for a very short period and appears to have blew all 3 boards, X/Y/and Z do not work now...

They are mailing me a new control box tomorrow, and told me to try driving another ground rod for the table grating, any other ideas?

[jimcolt]

What make and model plasma? Any pictures of your machine? Do you have a ground rod / grounding scheme?

Jim Colt Hypertherm

Running Mach 3 software, the control box is from Probotix. The boards that keep popping are in the link below. http://www.probotix.com/stepper_motor_d ... ProboStep/

It has been popping the Y-Axis board mostly, two times when I first got the table as soon as I would try to make a cut replaced the board), then after talking to the manufacturer, they told me to make sure the ground rod going to the grating on the table was attached well, now, so then I attached the ground rod directly to the material I was cutting (with the plasma ground clamp), that seemed to work, I was able to cut a few things out. Now today I was cutting and it blew the Y-axis board again. After swapping the board out, it worked for a very short period and appears to have blew all 3 boards, X/Y/and Z do not work now...

They are mailing me a new control box tomorrow, and told me to try driving another ground rod for the table grating, any other ideas?

[tacoma747]

Plasma is a ESAB PCM 875

As for grounds:
Control box is grounded (to the ground terminal)
Plasma cutter is grounded, to the chassis ground terminal
Tables is grounded, connected to the rod that goes through the grating.
All 3 have a separate ground rod. I am going to run another ground rod for the table grating.

I just don't see how feedback or voltage can be going through the motors, the plasma torch is not connected to a 'ground' in any way, the spike would have to be jumping from one insulated wire to another.

OR, I guess maybe the spike could be going through the table grating, through the drive assembly where the gantry contacts the table and back through the drive motors?

Is there anything I can do in conjunction with more ground rods to prevent this?

[JJsCustomDesigns]

Dont most ESAB Plasma machines use a High Freq start?


I know when i was shopping for a plasma cutter. I was told ESAB is a no no

[jimcolt]

The PCM875 is a high frequency start plasma. It is not a "spike" that is damaging your boards, likely it is the high frequency (15,000 volts, 2 megahertz) starting circuit that fires at the beginning of each cut cycle to ionize the air in the torch. Indusrial grade cnc machines are built using hardened cnc controls (not PC's or Laptops) that are designed with optical isolation on all inputs and outputs.....the drive amplifiers are built similarly with shielded, grounded cables. The torch leads on man of these machines are routed in separate power tracks an often are shielded and grounded directly to a driven earth ground.

It is extra hard to design a cnc machine using off the shelf drives and a PC or Laptop designed for office use...that will work well with a high frequency start plasma. It can be done, but requires very careful cabling , grounding and layout of components in order to minimize the effects of this electrical noise. Most of these types of cnc machines are equipped with a plasma that does not use high frequency as the torch starting method.

High frequency/high voltage travels on the outside of conductors and can easily couple (capacitively and or inductively) through insualation...hence the need for shielded, grounded motor/drive/computer cables and optical isolation for all of the low voltage cables.


Jim Colt

Plasma is a ESAB PCM 875

As for grounds:
Control box is grounded (to the ground terminal)
Plasma cutter is grounded, to the chassis ground terminal
Tables is grounded, connected to the rod that goes through the grating.
All 3 have a separate ground rod. I am going to run another ground rod for the table grating.

I just don't see how feedback or voltage can be going through the motors, the plasma torch is not connected to a 'ground' in any way, the spike would have to be jumping from one insulated wire to another.

OR, I guess maybe the spike could be going through the table grating, through the drive assembly where the gantry contacts the table and back through the drive motors?

Is there anything I can do in conjunction with more ground rods to prevent this?

[tacoma747]

What should I do to solve the issue? I'd prefer to not have to buy a new plasma cutter, I know I may need to evenutally, but don't really want to do that just yet.

I guess routing the torch lead as far away from the x-y-z leads would be a good start? I bought another ground rod today, what should I connect to it, aside from the grating that is.

Thanks for the info!

[jimcolt]

1. Position the plasma cutter as far away (opposite side of the machine?) from the electronics, drives, computer and any associated cables.

2. Route the torch leads as far away from all of the above as well.....do not coil any excess length.

3. Use shielded cables for all motor cables....ground the shields at one end only (the end closest to the ground rod)....with a ground lead going directly to a "star" ground point at or near the ground rod. Each cable needs its own ground to route any stray voltage back to the ground rod.....no "daisy chaining" of round wires as this will cause ground loops.

4. any wires or cables to or from the electronics (drives and I/O) should be shielded /grounded in a similar manner as listed above.

5. Interface cable from plasma to electronics should be kept separate from all of the above cables.....do not coil any excess length. This cable should be shielded and grounded as well.

6. Power cable for the plasma should be kept separated from all other cables....and the plasma should be on a dedicated, separate circuit from the computer and machine electronics.

7. Work ground for the plasma should connect (bolted, not clamped) directly to the same star ground as all of the other ground wires....then a stranded cable of the same size should connect from the star ground directly to the cutting table slat bed.

8. It is also a good idea.....for power line isolation...to run all of your electronics (drives, I/O, computer) plugged into a good quality UPS (uninteruptible power supply) ...available at office supply stores....look for one that can handle the wattage your equipment will draw...and also look for one that has surge suppression capability.

All of the ground wires should be relatively heavy gauge stranded wire....this is much more efficient in getting the RF electrical noise back to the ground rod. All of the above will not guarantee the end to your noise problems.....but will definitely be a step in the right direction. Often it is cheaper and less time consuming to just use the correct plasma!


Jim Colt Hypertherm

[tacoma747]

Sell me a new one cheap I can't afford to spend $3K + right now, wish I could but I'm gonna have to make do with what I have for now.

I searched EBAY, can't really find a good supply of shielding sheathing to run over the torch cable, guess I will keep looking.

If I went the route of buying a new torch in the future, would the machine torch I am using work on a different brand? I am guessing it might just take an adapter to fit a different brand plasma. I am using a Cebora CP-70 torch.

Thanks

[tacoma747]

Well I bit the bullet and bought a new plasma cutter. I bought an Everlast PowerPlasma 60C, it's specifically made for CNC cutting, got it for $1000 shipped with some extra consumables. Didn't like the idea of a Chinese unit, but it seems most electrical stuff comes from china anyways, and the reviews have been pretty good on them. Plus, a 5 year warranty is good for me. If it lasts 5 years, it would have more than paid for itself by then. I've seen plenty of name brand machines at the local welding supply store that had bad circuit boards, and the boards were too expensive to even bother fixing...

Thanks for the help, now I just hope I can sell this PCM 875, or at least the machine torch I bought for it...

[jimcolt]

The Everlast units use either high frequency / high voltage start.....or blowback start (non high frequency). Hopefully you purchased the blowback start model...otherwise you may still have the electrical noise issue.

Jim Colt

Well I bit the bullet and bought a new plasma cutter. I bought an Everlast PowerPlasma 60C, it's specifically made for CNC cutting, got it for $1000 shipped with some extra consumables. Didn't like the idea of a Chinese unit, but it seems most electrical stuff comes from china anyways, and the reviews have been pretty good on them. Plus, a 5 year warranty is good for me. If it lasts 5 years, it would have more than paid for itself by then. I've seen plenty of name brand machines at the local welding supply store that had bad circuit boards, and the boards were too expensive to even bother fixing...

Thanks for the help, now I just hope I can sell this PCM 875, or at least the machine torch I bought for it...

[tacoma747]

The Everlast units use either high frequency / high voltage start.....or blowback start (non high frequency). Hopefully you purchased the blowback start model...otherwise you may still have the electrical noise issue.

Jim Colt

Jim,

I bought the 60C, it was specifically made for CNC cutting, as stated on the everlast website: "High Voltage/Inductor Start is excellent choice for CNC operation with the fastest pierce times. This is different than HF starting as the frequency is lower, reducing the risk of interference associated with typical HF/HV starts." I am not an expert, BUT after talking to the sales guy on the phone, he assured me the hi-freq that was causing the problems with the ESAB would not be an issue. That said, if it fries a board, they have a 30-day money back deal, so I can send it back to them...

http://www.everlastgenerators.com/Power ... 66-pd.html is the one I bought. It will be here next Friday, we'll see how it goes, you can bet if it fries the board I'll be calling them to complain. I am still going to drive another ground rod, and take other precautions (like separating the torch lead from motor wires in the tracking, and probably tie the sheath grounds on the motor wires to a ground rod.

[jimcolt]

The system you bought is a high frequency start.....instead of creating a high frequency AC surge to ionize the gas it uses an inductive discharge......which makes almost identical electrical noise as the Esab system. They also have in their product line a "blowback" start torch.....which is more like the Hypertherm Powermax units that do not use high frequency....which would certainly be a better choice to solve your issue.

Good luck with the new system....but I would think that it will perform similarly to the Esab. I have been working with plasma systems for 35 years....I have fought high frequency issues many times!


Jim Colt

[tacoma747]

The system you bought is a high frequency start.....instead of creating a high frequency AC surge to ionize the gas it uses an inductive discharge......which makes almost identical electrical noise as the Esab system. They also have in their product line a "blowback" start torch.....which is more like the Hypertherm Powermax units that do not use high frequency....which would certainly be a better choice to solve your issue.

Good luck with the new system....but I would think that it will perform similarly to the Esab. I have been working with plasma systems for 35 years....I have fought high frequency issues many times!


Jim Colt

Turns out they had the website incorrect. It is NOT HF start, it is Hi Voltage, Low Frequency. It will be here tomorrow, although I am still waiting on the control box for my table. I will update with how it works.

[jimcolt]

"Turns out they had the website incorrect. It is NOT HF start, it is Hi Voltage, Low Frequency. It will be here tomorrow, although I am still waiting on the control box for my table. I will update with how it works."

The "High Voltage, Low Frequency" start that is used on some plasma systems (instead of the traditional high frequency)....which is generally around 10 to 15 kV at 2 mega hertz) is actually an inductive spike that is generated to ionize the torch gas. It will have a similar effect in regards to affecting sensitive electronics. Hopefully it will solve your issues.....let us know how it works!

Blowback style torches use the DC cutting power to ionize the plasma gas....virtually no electrical noise is produced with this technology....that will affect sensitive electronics and PC's.

Jim

[tacoma747]

I have cut some a few things so far, I can say I am impressed as of right now. When the ESAB cut, it was almost as if it was underpowered, the cut speed had to be slow (or it seemed it did to me) for it to cut through even 1/8" steel. I have cut more with the Everlast unit today than everything I cut with the ESAB unit, probably because the ESAB gave so many issues with the HF frying boards.

Once I get the THC dialed in, that should solve some cut quality issues (newbie stuff, I had to get ahold of the manufacturer to get some instruction on setting the THC, so I was running it without THC).

I plan to buy a DC TIG/Plasma combo so that I can have a portable welder/plasma, and also have a backup for this machine. Not saying I think it will break, but I plan on taking the table to a local fair this year, and IF it did, that would lose me more $$ than the TIG/Plasma combo would cost. Plus, I would like to have a handheld plasma so I don't have to use the 60C for double duty.

As of right now, I'd buy it again, especially for $1000 shipped!

[JJsCustomDesigns]

be Careful TIG welding to close to your plasma table. We had problems running the TIG welder and the PCam (at my last FT job) at the same time. Just a heads up.

[cypher]

How is the everlast plasma holding up? also I notice there is only one type of consumable how is the cut quality on different materials? could you post some pics thanks

[tm america]

i would go with a different plasma cutter..i was having all kinds of issues before i switched out my cutter.. I didnt want to spend alot for a cutter as well. i got a longevity 50i .. it is a 50 fully cnc ready unit..It uses a lifting electrode to start the arc so there is no high frequency or high voltage start.. it is a really nice unit.. Especially for around 800 bucks.. it comes with a 5 yr warranty and parts are fairly cheap to purchase such as replacement torches and consumables only issues is machine torches are a little on the pricey side but i think most are..Power is great as well i have no issue cutting 3/4 inch but most stuff i do is less than 1/2 inch.. I was using a miller spectre375 before and i could only cut 1/4 inch at around 20ipm. now with the 50i i can cut 1/4 inch at 75-80ipm and get a much cleaner cut with no isssues

[tacoma747]

How is the everlast plasma holding up? also I notice there is only one type of consumable how is the cut quality on different materials? could you post some pics thanks

The everlast unit fried back in December. Everlast told me they would do a 'rush' job on the repair (which I called BS on, especially since I NEEDED a working machine very soon after it broke). I bit the bullet a bought a Hypertherm PM65 and I will say it was WELL worth it.

If you cut a part here or there I can't say the Everlast is a bad deal, but the Hypertherm cuts better, consumables last alot longer, and it cuts ALOT faster (about 4 times faster on 3/8" steel). If you are cutting full sheets on a regular basis, don't even consider an Everlast. The speed of the Hypertherm pays for itself quickly.