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Author Topic: Where are the plasma THC settings  (Read 3417 times)

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Where are the plasma THC settings
« on: May 04, 2014, 09:24:21 AM »
 For the life of me i cant seem to find the plasma THC settings such as the anti-dive that everyone talks about and others. I have the screen that does have the THC on button and also shows the THC speed and up and down limits but it doesnt allow me to change those settings. Any one want to help out a rookie?

Offline Davek0974

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Re: Where are the plasma THC settings
« Reply #1 on: May 04, 2014, 10:30:22 AM »
Is there a box labelled Anti dive % ?

That is the limit before anti dive kicks in, mine is set at 90%

There is a box labelled Rate, that is the % of z feed rate that THC uses! there is no acceleration or deceleration here, my rate is 8%.
To alter the min and max and rate levels, click in the box, type the new value and press enter, it does not work unless you press enter.

Mine is  set at -5mm and +5mm, seems ok but my table is a small one.
« Last Edit: May 04, 2014, 10:32:01 AM by Davek0974 »
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Where are the plasma THC settings
« Reply #2 on: May 04, 2014, 11:44:40 AM »
 Ok, i am feeling dumber by the minute. I entered a value in the box and hit ENTER and whaola, it took it. I swear i tried that 5 times and it didnt work but i guess i was mistaken.

 I have no box labelled anti-dive.

 Also there is a box which has "THC speed" and a second box which has "THC Min Speed %". I can change the THC speed and the THC will react at the changed speed. But what is the Min speed used for?

 When cutting with my THC speed set to 20 the Z axis would move up so fast it ended up about 1" above the part and would not come back down to where it belonged during the cut. When i changed the speed to 5 the Z axis moved up and down perfectly when cutting at 30" per minute. But im afraid when i start cutting much faster the THC Z axis speed will have to change to match. So i guess this is a setting that must be adjusted manually depending on the XY cutting speed you will be using?

 Also when cutting small holes in diameter of .5" the Z axis was dropping down and dragging the nozzle around on the part. Is there any way to turn the THC on and off in the post processor to inhibit it during small cuts?

Offline Davek0974

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Re: Where are the plasma THC settings
« Reply #3 on: May 04, 2014, 12:40:50 PM »
I think you'll find the THC min speed is the point where anti dive kicks in, I.e. The minimum % of set cut speed that it starts anti dive, I have mine at 90% so I think that if speed drops to below 90% of my set feedrate it will not dive the torch.

Small holes I am still learning but, if you set a lower feedrate in gcode, it will not allow anti dive to work because the feedrate is now lower. What I am doing is to split my small holes out in cam and apply a manual THC off command before it cuts and THC on after, before going back to full cut speed, this seems to work but...

I have also just found that by tuning my speed and acceleration figures on the table, I don't need to slow down manually apart from small holes in thicker material which I do as described above, I can do a 10mm hole in 5mm plate at normal feed and let antidive deal with it.

Yes, I think if you change cut parameters a lot, I think you may need to up the THC rate a bit, possibly.
« Last Edit: May 04, 2014, 12:43:34 PM by Davek0974 »
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Where are the plasma THC settings
« Reply #4 on: May 04, 2014, 01:33:02 PM »
 Ok. So THC Min Speed % = Anti Dive? I will play with that and see what i get.