Another Valid Arc Lost Post

phillc54 wrote:

Just remember that if your plasma cutter decides the arc is lost, its going to cut the arc regardless of any synthesised arcOK signal

I would think that if a reasonable quality plasma cutter thought that the arc was lost it would ensure the arc was turned off.

Can you post a screenshot of your Config panel and your Run panel.

Thats what I said, "cut the arc" ie turn it off.

rodw wrote:

phillc54 wrote:

Just remember that if your plasma cutter decides the arc is lost, its going to cut the arc regardless of any synthesised arcOK signal

I would think that if a reasonable quality plasma cutter thought that the arc was lost it would ensure the arc was turned off.

Can you post a screenshot of your Config panel and your Run panel.

Thats what I said, "cut the arc" ie turn it off.

So what is the issue then?

phillc54 wrote: [

So what is the issue then?

You know my views on this. The plasma manufacturer provides a mechanism to tell the CNC controller the arc has been lost (and when a valid arc has been established). Where this signal exists, it makes no sense to bypass it. Surely there is no user on this forum who honestly thinks they know more than Hypertherm about Plasma cutting?

And yes, I know it takes a while to establish an arc on thick plate. My Thermal Dynamics takes quite a while on 16mm (5/8") to establish an arc too. But if you take off before that arc is properly established, why would you be surprised if the arc fails during the cut when it never got properly established in the first place?

You know my views on this.

Yes, I have seen them written often.

The plasma manufacturer provides a mechanism to tell the CNC controller the arc has been lost (and when a valid arc has been established). Where this signal exists, it makes no sense to bypass it. Surely there is no user on this forum who honestly thinks they know more than Hypertherm about Plasma cutting?

I don't know of any one here who does think like that but I also don't think that soft Arc OK is as much of an issue as you say.

I have used both methods, and they do work properly when set correctly, but i still prefer to use the hardware ARCOK, as can be noticed from the builds i do, i add that to most of the plasma cutters, be it with an reed contact or and inductor and some added electronics.
With software there are several issues to deal with to get it right, some plasma cutters will continue to output voltage in the range of 150 to 280V even after the torch is shut off since they have capacitors and that voltage will slowly fall back to 0 so for a split second when the torch is turned of the THC will start moving it down. Never really a big issue as it never reaches the material.
Some, especially inverter ones will have a 160 to 180V on the torch in cases where the pilot arc "missed" to transfer or did not strike an arc, so that will also cause the THC to synthesize the ARCOK signal and start moving torch down to lower the voltage while there is no arc or cutting going on.n Same thing happens on transformer plasma's but the voltage is much higher up to 280V, so the THC will move down rapidly and hit the material.
On my last build using THCAD i have the min arc voltage set to 80V and max at 150V to avoid any of those issues, and it works perfectly, never missed a single start.

phillc54 wrote: Check Arc Fail Timeout in the Config Panel

linuxcnc.org/docs/2.8/html/plasma/plasma...de.html#config-panel

THC Delay works identically for all modes.

EDIT: Set Arc OK High really high until you tune it in.

I missed the edit. Sorry about that. It was pretty late for me. I have the arc ok set as high as I can get it, 300v.