Pncconf qtplasmac

The Ohmic Test button will not cause the Z Axis to move.  It is just used to see if the tip is shorted, or that the ohmic loop is currently "shorted".  This normally occurs via water in the tip on a water table.  

In a normal table where everything is operating correctly, pressing Ohmic Test will cause nothing to happen. If the tip is shorted on the same table, via water, dross, etc. the OHMIC light will light up, letting you know to fix the situation.  

If the truth was confused, now hypersensing with ohmic is working, do you know if there is any difference with Ohmic3 is it worth using? And I am also doing the probe test but the probe touches and it takes time to rise again quickly.

Rod will have to chime in here, but ohmic3 attempted to use a moving-average algorithm to increase the tolerance with water from a water table and give less false positives, etc.  

I moved away from the THCAD version of ohmic sensing, as after a ton of testing, I found it to be overly complicated from a software and setup standpoint, and unreliable.  I found the most effective method of water tolerance to come from changing the resistor value.  Further, I had issues with it "building a charge" and giving false positives.  I moved over to ohmic sensing with 2 simple relays (arguably could be done with one), and have had no issues.  It's also supported by QtPlasmaC natively.

There's always more than one way to solve a problem I reckon.

paulsao wrote:

If the truth was confused, now hypersensing with ohmic is working, do you know if there is any difference with Ohmic3 is it worth using? And I am also doing the probe test but the probe touches and it takes time to rise again quickly.

If Ohmic is working for you, I would leave it at that.

Ohmic3 was written in response to guys using Hypertherm 45XP's on a water table. They found that water entered the tip and shorted it out meaning ohmic sensing did not work.  My machine was not as susceptible to this.This is not specific to sensing with the thcad. (ASIDE: One of the reasons the pulse torch button is there is to allow you to get airflow going before starting a program to deal with this - c/- islander261 on this forum).

When the torch is wet inside, there can be a very low voltage hysteresis (<0.2 v) between the on and off state and it was hard to configure the voltage on and off thresholds in Ohmic3 to get reliable sensing. Its certainly not possible with a conventional relay which often have < 10v hysteresis between on and off states.

Ohmic3 uses moving averages and dispenses with the need to specify a low voltage threshold. When Ohmic 3 sees the on threshold crossed, it records the peak voltage and moving average seen. When the voltage falls below the moving average (which will be lower than the actual voltage), the probe signal breaks. The circuit was modified to include a 25k 5 W resistor to increase the high/low hysteresis per PCW's suggestion.


 

Thanks Rod for your great help I decided on ohmic3 and it works well, the new 25k resistance you are talking about goes between in + and in? 

Try this