[mulligan]

FINALLY had my table completed and running perfectly. X, Y, and Z axis were working flawlessly... Then I triggered my plasma for the first time and everything went down hill from there. Now my x axis will move only one way, no matter which direction I tell it to move. Y axis driver will not even turn on and z axis still works fine but I assume it is because of the cheap uni-polar driver it has.

I'm using these drivers from Craig at Quick Step (http://cpwojcik.home.att.net/QSDriver/Page_1x.html) and a High Frequency plasma cutter. My plasma was 15' from the electronics and isolated from the table.

Ideas?

[Torchhead]

You plasma is isolated from the table? Or do you mean the electronics (motor drives and PC logic) are isolated. If your drives don't have isolation on the Step & Dir and you don't ground things perfectly you can get surges from the HF palsma that kills logic level electronics. Using a HF plasma with a system designed for plasma (where isolation is planned and done in every part of the electronics) is often a challenge from a noise perspective but bad grounding can destroy drives and even your PC if you don't have isolated inputs.

I fear you are trying to apply a hobby level solution to an industrial cutting problem.

TOM CAUDLE
www.CandCNC.com

[Ajax-oz]

Hi
I'm with Torchhead. A grounding issue.

Can you give more details about your setup and pics.
Grounding and Isolation of the plasma torch is critical.

Is your cutting bed, part of the CNC gantry
Do you have both cutting bed & gantry Grounded using a very good ground. 1" - 2" wide (depends on plasma size) Braid earth cable (works the best) on both cutting bed and gantry. one each
does the torch have an Isolation block that it is mounted on.

AJ

[mulligan]

AJ and Tom you have hit the nail on the head. "I fear you are trying to apply a hobby level solution to an industrial cutting problem" is the best way to describe my situation.

I have my table setup in a 12'x20' garage and I have operated the plasma with no ill effects in the past. The only change this time was I fired the cutter with the tip touching the table and the torch ground clamp was left hanging on the plasma cart... (nuts)


New plan of attack...

1. Earth ground attached to torch chasis and driven 4' into the ground. (Have done this already, BUT this ground rod is within 3' of electrical panel rod)

2. Wire sheathing covering the torch lead from chasis all the way to handle on the gantry.

3. Move all my electronics (drives, power supply, Print port protecter, etc) into a steel weather proof enclosure. Should this be case be earth grounded also? Currently and I am ashamed to say, everything is mounted on a temp sheet of plywood... (nuts)

4. Rubber mount my motor mounts on my table. Since I have a timing belt setup, will this be sufficent for isolation?

5. Ensure that ALL grounds terminate with my power supply ground.

6. Ground only one end of the wire shields.

7. Enclose torch case in a steel box if necessary?? The torch has its pilot arc in its case unlike my Hypertherm 600 which has it at the torch tip.

Should I switch to the hypertherm cutter??

[mulligan]

Is your cutting bed, part of the CNC gantry

Yes. I have the typical 5/16 roller blade bearings for the gantry rollers.

Do you have both cutting bed & gantry Grounded using a very good ground. 1" - 2" wide (depends on plasma size) Braid earth cable (works the best) on both cutting bed and gantry. one each

Nope, but I will definitely install them.

does the torch have an Isolation block that it is mounted on.

I have an aluminum block the compresses around the ceramic cup on my torch handle for a torch mount. This block is mounted to a piece of HIWIN rail and then to HIWIN bearing blocks.

I'll try to get pics but I have dial up and is extremely slow.

[Med-Pac]

We had similar problems when we were first setting up our plasma table. We had to isolate the plasma lead from the driver wiring to solve the prob. We put all of our wiring from our motors in the snap together cable way. Then we built a few cable whips to hold the plasma cable away from everything. Been working great ever since. Here's a few pics.

Mike

[Ajax-oz]

The only change this time was I fired the cutter with the tip touching the table and the torch ground clamp was left hanging on the plasma cart... (nuts)

That will cause you problems nearly every time.

Something to remember with anything electrical is that the current is trying to get to ground as fast as possible.

So when you left the plasma ground lead off your cutting table the current found another way to ground. It just happen to be through your drive motors to the controllers.

What you are planning on doing to improve your system looks good.
This is my thoughts.

1. Earth ground attached to torch chasis and driven 4' into the ground. (Have done this already, BUT this ground rod is within 3' of electrical panel rod)

Originally Posted by Ajax-oz View Post

Is your cutting bed, part of the CNC gantry

Yes. I have the typical 5/16 roller blade bearings for the gantry rollers.

Excellent
attach ground to the your cutting table.
The Gantry concerns me may need to have a ground connected to it as well. It would depend on the design.

Cable the that same size (or larger) as the earth on your plasma unit would do. I like using the flat braid for earths but they aren't convenient to use over longer distances.

Remember you still need to connect your earth from your plasma unit to the cutting table. The extra earths protect your electronics and you form being fried.

2. Wire sheathing covering the torch lead from chasis all the way to handle on the gantry.

Excellent
Helps reduce RF

3. Move all my electronics (drives, power supply, Print port protecter, etc) into a steel weather proof enclosure. Should this be case be earth grounded also? Currently and I am ashamed to say, everything is mounted on a temp sheet of plywood... (nuts)

Excellent
Mount your steel weather proof enclosure to your chassis if you like.
Yes it should be earthed
I normally have a braided earth strap from the enclosure to the chassis, even if it is directly bolted.
Remember to remove the paint for the earth

4. Rubber mount my motor mounts on my table. Since I have a timing belt setup, will this be sufficent for isolation?

Not needed in my opinion
Motors need to be grounded as well.

5. Ensure that ALL grounds terminate with my power supply ground.

If you do as you said in number 3 this will be done in your steel weather proof enclosure.

6. Ground only one end of the wire shields.

excellent

7. Enclose torch case in a steel box if necessary?? The torch has its pilot arc in its case unlike my Hypertherm 600 which has it at the torch tip.

Should I switch to the hypertherm cutter??

I think it will most likely not be needed, but I could be wrong.
I work on the Hyperthem & Kaliburn (Inner Logic) 200A + units, so I don't now anything about the models you are talking about.

Here is a link to some of the equipment I work on
http://www.profilecuttingsystems.com/pcsproducts.html

I have an aluminum block the compresses around the ceramic cup on my torch handle for a torch mount. This block is mounted to a piece of HIWIN rail and then to HIWIN bearing blocks.

It sounds like your torch is isolated nicely.

hope this helps

AJ

[Ajax-oz]

We had similar problems when we were first setting up our plasma table. We had to isolate the plasma lead from the driver wiring to solve the prob. We put all of our wiring from our motors in the snap together cable way. Then we built a few cable whips to hold the plasma cable away from everything. Been working great ever since. Here's a few pics.

Mike

med-Pac you should be able to run control cables and plasma cables in the same snap together cable way.
If you are having problems it is most likely grounding & shielding issues causing interference.

Simple fix

All cables to be shielded and earthed at one end.
Cable tie plasma cable to one side of flex cable duct and other cable to the other side. power cables in the middle.
Have separate earth on machine. not just the plasma and electronics earth.
Make sure control box also has a good earth.

Do as mulligan has done and drive a earth stake 4' or more into the ground near the machine.

When I install a plasma profile cutter I drill a hole into the floor next to the machine and drive earth stake in there.
Now I know you may not want to have a hole in your garage floor, but try and put one in just out side near the machine.

I would recommend to any one with a plasma profile cutter to have a separate earth connected to there machine that is able to handle currents the same amps as the plasma unit being used.

This is for two reasons.
first it will save your motors and controllers most times if something goes wrong with plasma unit.
eg. for get to connect the plasma unit earth cable to cutting bed.

Second
Safety.
with no earth connected and you try to use the plasma cutter, the whole profile cutter is live and looking for a way to ground.
If you touch the machine you could become the earth connection.

Not a good end result for anyone.

AJ

[mulligan]

Thanks AJ.

I'll be spending the next week getting things in order while waiting for my new drives.

Any leads on wire sheathing with 1" ID?

[mulligan]

Well it looks like I lucked out. All that was fried is my Printer Port Protecter, thankfully. I've ordered a new one and began to properly ground and enclose the electronics.

[Ajax-oz]

You are lucky it is only one thing that got fried.

As a thought you might want to have a good look at your cables to see if there are any signs of melting and or damage due to higher current going through them.

just run your hand over them and feel for bubbles / blisters in the insulation.

if there is a problem it should only be one cable. But it is best to check them all due to the type of fault you had.

AJ