Plasma Issues

[TonyWish]

I have a Camaster CNC with a plasma and spindle. I love both metalworking and woodworking so it was a natural to get both. I have set up my plasma first. I am using Aspire for the design and WINCNC for the machine operating system. When I first started it seemed most of the issues were "NEWBIE" items. As I have learned the machine I have found that I can't get arc voltage to the settings in the Thermal dynamics manual,Torch height control is intermittant, sometimes the plasma doesn't cut all the way through even though it just made a good cut before. I have grounded and ungrouded between computer and machine with no real results. I have my computer plugged in the same outlet as the plasma and CNC machine. I have switched with no discernable results. I have played with the config settings. It seems that my parameters are way off of what the book calls for as a starting point.

I see torch height control somewhat work on a slanted surface. The head goes up with the slope but doesn't come down.

Also what should be a good arc voltage for .125 mild steel. I am using 80v.

If you have went through any of this please enlighten me because I am at the height of frustration

Tony

[Mike 1948]

Originally Posted by TonyWish I have a Camaster CNC with a plasma and spindle. I love both metalworking and woodworking so it was a natural to get both. I have set up my plasma first. I am using Aspire for the design and WINCNC for the machine operating system. When I first started it seemed most of the issues were "NEWBIE" items. As I have learned the machine I have found that I can't get arc voltage to the settings in the Thermal dynamics manual,Torch height control is intermittant, sometimes the plasma doesn't cut all the way through even though it just made a good cut before. I have grounded and ungrouded between computer and machine with no real results. I have my computer plugged in the same outlet as the plasma and CNC machine. I have switched with no discernable results. I have played with the config settings. It seems that my parameters are way off of what the book calls for as a starting point. I see torch height control somewhat work on a slanted surface. The head goes up with the slope but doesn't come down. Also what should be a good arc voltage for .125 mild steel. I am using 80v. If you have went through any of this please enlighten me because I am at the height of frustration Tony

Like you said, your voltage seems pretty low, my Thermal Dynamics Cutmaster 52 says 110-125 volts depending on the amps and tip used.
About the only time I can't cut through a part is when I forget to put the ground clamp "ON" the material I'm cutting, not on the frame of the machine.

Good Luck
Mike

[Dustin407]

I agree, your voltage seems pretty low try this... 60 amp tip 105 volts 115 ipm.... this should get you in the ballpark... You may have to mess with your height control settings you could have the anti-dive on thats why it wont come back down on the z axis... that is for safety reasons so it doesnt drop over a void which is a terrible thing I know because it happened to me...

[jimcolt]

First....it sounds to me that your height control is not working properly as you say it rises ("the head goes up with the slope but does not come down") but does not follow the plate.....so I would suggest you work with the machine manufacturer and/or the height control manufacturer to get the height control sorted out.

Here is what a full function height control needs to do:

1. index the torch down to the plate, locate the surface then retract to the pierce height. The pierce height should be set to the torch manufacturers suggested pierce height for the material type and thickness being cut.

2. The THC then fires the plasma, and stays at pierce height with no x, y or z movement until the pierce delay times out. Pierce delay also should be set to the torch manufacturers specifications for the material you are cutting...this delay allows the plasma gas pressure to stabilize and allows the arc to fully penetrate the plate....both of which will make the torch consumable parts last longer.

3. As soon as the above is complete, the torch should now index down to the cut height (again from the torch manufacturers specs), and x and y motion should start.

4. On most THC's there is either an AVC delay (this is a delay that allows the machine to accelerate up to the programmed speed...then when complete allows the arc voltage feedback to take control of torch height) or an output from the cnc that activates arc voltage control (avc) whenthe machine is within a certain percentage of the cut speed. If your arc voltage setting is correct.....you should see the torch maintain the same height as the cut height after the avc becomes active. If the torch rises, then the arc voltage setting (set by the operator) is too high.....lower it until the torch is at the proper physical cut height during the cut. If the torch dives into the plate...raise the arc voltage.

As far as voltage settings that are recommended by the torch manufacturer...these are suggested starting points assuming you have every parameter set exactly as the manual says....and it also assumes that the THC you are using has been accurately calibrated to your particular machine (different wire sizes and lengths can make a big difference on height control voltage). The best rule of thumb is to get all your parameters set where you best like your cut quality...then adjust the arc voltage setting while at steady state cutting speed...until the physical cut height matches the manufacturers suggestion.....that setting will be the voltage that is correct....don't worry if it is different from the specs in your manual. Physical torch to work distance is the key to best cut quality.

A couple of other suggestions:

1. Ensure that your plate is making excellent electrical contact to the work ground lead of the plasma. Best practice is to bolt the work ground securely to your machine frame, then run another wire (same gauge as the plasma work ground) from this same bolt up to the plate....clamp this cable (use an alligator clip or welding clamp of sufficient current rating) directly to the plate you are cutting. Often...height control issues are caused by a voltage drop between the plate and the slats and the plasma work ground.

2. A ground rod driven next to the machine is highly recommended. You are using a computer that was designed to sit in an office....in a shop with a highly magnetic, pulse width modulated (electrically noisy) plasma cutter......without proper system grounding you can expect the computer to do strange things as electrical noise interference can easily couple through cables. I also recommend on these small machines that you buy a good quality UPS (uninterruptible power source) with surge protection from an office supply store...plug both your computer and your machine power into the protected outlets on this device.....often issues are eliminated.....electrical noise can couple to your computer through the 120 AC supply...and the UPS tends to isolate and filter the power.

Jim Colt Hypertherm

Originally Posted by TonyWish I have a Camaster CNC with a plasma and spindle. I love both metalworking and woodworking so it was a natural to get both. I have set up my plasma first. I am using Aspire for the design and WINCNC for the machine operating system. When I first started it seemed most of the issues were "NEWBIE" items. As I have learned the machine I have found that I can't get arc voltage to the settings in the Thermal dynamics manual,Torch height control is intermittant, sometimes the plasma doesn't cut all the way through even though it just made a good cut before. I have grounded and ungrouded between computer and machine with no real results. I have my computer plugged in the same outlet as the plasma and CNC machine. I have switched with no discernable results. I have played with the config settings. It seems that my parameters are way off of what the book calls for as a starting point. I see torch height control somewhat work on a slanted surface. The head goes up with the slope but doesn't come down. Also what should be a good arc voltage for .125 mild steel. I am using 80v. If you have went through any of this please enlighten me because I am at the height of frustration Tony

[TonyWish]

Thanks guys for your help. I will try to implement these asap. On the ground rod Jim, how long etc. I'll have to drill through a 6" concrete floor then have rocks to deal with since I am in Colorado. also it seems water splashing up to the tip is an issue. Any suggestions for how much water to have in a pan under the material. I have a 4 " pan with 3 1/2 " grids. How low under the material should the water be?

Thank you all for your help!!

Tony

[jimcolt]

The water will not affect the normal height control functions...but it can affect cut quality and dross on the parts. Each plasma torch is a little different....so I would just experiment with the water level....too high means a lot of splashing, too low means a lot of smoke. I use a downdraft table on my machine...no water.

On the ground rod...normally they are about 8' long. I was able to drive in a 6' one here in NH pretty easily.

Jim Colt

[Dustin407]

If you want a quick fix on your ground you can always attach a thick ground cable to an exterior steel water pipe. Usually where your water hose is connected, those pipes run under the ground pretty far into the foundation plus the water inside acts as a great nuetralizer.... But yes I agree a steel rod in the ground 6-8' will work great. I work on a lot of movie sets in orlando as a grip, the first thing we do when we are on the movie set is hammer a 7' rod into the ground for our 440 volt generators....

The water level height is very important i came to find out. I noticed if the water is directly below the material ( about 1/32" ) you get alot of pulsation which is not good for edge/cut quality. Too low the material can warp and you get some smoke inhalation. I try to keep the water about 5/16"-3/8" below the material. I noticed I get the best cut quality at this height for me.