Ohmic sensing and water

[adscnc]

Does any one have experience using Ohmic sensing on a water table?
Does the water ever short out the circuit and give a false read ?
Whats your experience ?

[djreiswig]

It can, but usually only on the first Pierce since after that the post flow air blows the water away.

[acourtjester]

I also have had very little problems with water and the ohmic sensor. I put a probe led on the program page and see it light if water has caused a problem. I just remove the shield and nozzle and dry it off problem cured.

script 3.JPG

[SeanP]

Very little problem with water, bits of spatter or rust are give me more trouble, it's very good compared to touch off sensing.

[TJS]

I just tried this last nite. I did a dry run on a part. However there was a puddle of water where I was testing. I noticed my torch tip was not touching the metal during the test. Wouldn't ya know it. It was hitting the water and creating continuity and torch would pick up like it touched off. However as Acourtjester was saying the air blows the water away anyway. I thought of this post.

[SeanP]

I put a probe led on the program page and see it light if water has caused a problem.

Now there is a good idea!
Might get chance to do a few jobs like that over Christmas now, my PM45 unit has just packed in this morning!

[acourtjester]

Here is how I made the change to the screen set to show a Probe LED on the Program page.
I found this video to show how to do similar things, He has many videos but seem to be more about routing.
https://www.youtube.com/watch?v=F1Siihp0nSo&t=611s
First go to Mach’s web site and download the screen 4 add on and place it into the Mach 3 main folder so you can execute it from there.
https://www.machsupport.com/downloads-u ... creensets/
After you have it running you bring up the screen set you want to modify.
Short video on how I did the change
https://drive.google.com/drive/folders/ ... sp=sharing

[SeanP]

Here is how I made the change to the screen set to show a Probe LED on the Program page.

You definitely are the elite of elite members on here Tom! many thanks for the info, the video you made is great, I actually have changed all of my screenset but it was a while ago now and have probably forgot half of it, that will help me along nicely, thanks again.

Screen.png

[SeanP]

Just order a 65 this afternoon as well by the way

[acourtjester]

Well Merry Christmas what a nice gift to yourself
happy to help

[Rodw]

I found a few issues moving to a water table with ohmic sensing. A good controller like the Linuxcnc plasmac config helps becasue its 100% perfect with recovery. Occassionally, it will sense way too high as a splash hits the tip. All I have to do is hit pause and resume and plasmac will reprobe and get it right. I also have had issues with water inside the shield top shorting out, but that is easy to fix by getting some air flow through the torch either by flicking the switch on the TD A120 console or pulsing the torch using Plasamac.