Advanced Search

FlaredFins wrote:

 I am set to Mode 1 for qtplasmac so wondering if with the THCAD2 do I really need the arc ok in signal?

Which leads me to query why the mode is missing from your ini file?
If you have an arcOK signal built in to your plasma (Which you have) I recommend mode 1. Using Synthesised ArcOK can create spurious signals that can cause the symptoms you describe if not set up correctly.

Specifically, on piercing, the voltage does not climb constantly. It often dips down. If the ArcOK has been enabled  this can be sensed as a loss of ArcOK (Although I believe QTPlasmac has some settings now that are supposed to work around this).

Its much better and safer to rely on what the plasma cutter is telling you than guessing no matter how smart the guessing algorithim is....

Up early this morning to get back at this and while in qtplasmac I don't have the arc ok light lit on screen, but it is signaling Plasmac.arc.ok.in. So not sure if this is creating issues. I am set to Mode 1 for qtplasmac so wondering if with the THCAD2 do I really need the arc ok in signal?

Very expensive prices, so I advise you to use such services as www.pirateship.com/ (you can also look at such service as sendle and compare prices with pirateship and shipping to a particular country) 

or I suggest you just buy a couple of shipping labels through labels.vs (the purchase function opens after registration).

andypugh,  parcelmonkey compared to pirateship or sendle is also an expensive service
 

In this case, it acts as a dead short for the AC interference while the HV start/pilot is on, it does not affect the DC voltage that THCAD needs to measure.

tommylight wrote:

Nope, that is 1uF, you need 0.1uF or 100nF
It does not mater much where, but i would still place the capacitor at the THCAD input, resistors inside the plasma.
Not a DC capacitor nor electrolytic one, metal film have no polarity and are good ad reducing interference.
 

While I greatly appreciate all your advice, it bother me to not understand why I'm adding a capacitor. Would you have some ressources where I can learn what this capacitor does in this case ? I tried to look it up but I dont even know where to start, there is so much information.

Does the capacitor act as some kind of "electronic spring" to absorb a HV surge ? And how did you know which capacity and voltage it should have ?
 

Nope, that is 1uF, you need 0.1uF or 100nF
It does not mater much where, but i would still place the capacitor at the THCAD input, resistors inside the plasma.
Not a DC capacitor nor electrolytic one, metal film have no polarity and are good ad reducing interference.

tommylight wrote:

polskleforgeron wrote:

Also when you say you plugged the cheap china plasma through 2 resistors (both 1MO 2W) with a capacitor (0.1uF and what power rating ?) shorting the two, would it look like that :
 

Exactly !
Capacitors have no power rating, just capacity and voltage, sometimes temperature range in a form of a single letter. Anything from 300-500V will do just fine.
 
 

Is it better to add the resistors and capacitors closer to the THCAD-2 or the connexion in the plasma cutter ? I feel like it would be better at the source, inside the frame of the plasma.
Also dumb question, I can easily fin some 300V AC 0.1uF capacitors. But we're talking DC here right ? Is it still OK or should I find a specific DC one ? I remember something about electrolytic capacitors that can only be use in DC..

Some pictures of the project !

 

tommylight wrote:

@Rod,
He mentioned several times he has a HF/HV start plasma, the THCAD manual clearly states not to use that combo.
Having cleared that cautionary tale, THCAD can work with HF/HV start as can be proven by probably 10 i have in use daily, just some care must be taken when wiring to choose a suitable point where the HF has less effect, usually at the rectifier output or at the built in HF filter/protection.
And additionally a few days back i wired a THCAD10 directly to outside connectors on a new cheap china inverter plasma with HF start, THROUGH 2 resistors and added a 0.22uF/350V capacitor across the THCAD input just to be on the safe side, and it also filters the readings a bit. Used it for 2 days, all good, probably did over 200 starts as i was tuning voltage/feed/air so made a lot of 100x10mm rectangles.
Just to be clear, do this at your own risk, any mishaps usually end badly.
A 0.1uF capacitor would be better, did not have one with such high voltage.
 

Thank you again for your explanation, but it's a bit technical for me and I'm not sure to understand.

When you say "just some care must be taken when wiring to choose a suitable point where the HF has less effect, usually at the rectifier output or at the built in HF filter/protection", do you mean that I shouldn't take the arc voltage the "simple" way from the ground clamp to the torch electrode, but instead get the wiring inside the Plasma cutter ? I think maybe I can do that..

Also when you say you plugged the cheap china plasma through 2 resistors (both 1MO 2W) with a capacitor (0.1uF and what power rating ?) shorting the two, would it look like that :
 

I've added some pictures of the plasma's cutter inside :
 
 
 

 

OP has a choice between a HF start and a HF start with CPC port.
I worked with Stamos, it works fine, Stahlwerk before it also worked fine, meaning over a year of use for each, none of them mine personally.
Now under the covers, there were two reasons i did the last deed:
-New plasma under warranty, cheap Kzubr for 320 Euro, 60A, so could not open it.
-I had a THCAD collecting dust, so i risked it, it survived unscathed!
I was pretty sure it would work as i did add a capacitor across the THCAD input to short whatever HF gets to it and after the resistor drop should not be much to deal with, but the biggest surprise was it actually does 60A flat! That is in both 220V and 380V, and that raises a worrying question: what happens when someone less experienced gets it and plugs it into 220V and starts using it drawing over 30A from the mains! We (Europe) has a limit of 16A for anything 220V, so that will melt the plugs in a very short time.
380V is all good as it does roughly 18-19A, and we can do 16 or 32A depending on the socket size, probably should be fine with the small socket as it mostly will cut with 40-45A.
Again under the covers, i am mentioning all this as it applies to this topic, the plasma sources are all the same.

Wow that was fast!
Many thanks to you, really appreciate the work.

Have a great day!

Lol Ok I had just switched it back to 1.

Also is there anything else that needs to be looked at before I actually fire the torch? I know there were some changes needed for the other car with OHMIC sense but cant remember if there were files that need to added into HAL or the Ini. I set it up through PNCconf. just need to go back and set it for 32 again

32

What divider ratio do you use on the THCad2 1, 32, 64, 128?

7I96S+7I85S plasma config:

 

Note that because of the use of muxed encoders, the on 7I96S  encoders
are numbered oddly = 4,6,8

The 7i96s_7i85sd.pin file in the distribution is incorrect, but the
7i96s_7i85sd.bin file is OK (it has the INM on the TB3 pins)

Note that you _can_ still use the 7I96/7i96s TB3 inputs without the INM
(GPIO works). There are be 7I96 configurations without the INM
but the 7I96S's larger FPGA means it should always fit

Hi, I'm currently building myself and hybrid Plasma/Router CNC. 

I originally chose to go with the 7i96S with 2x THCAD2 (Ohmic & Arc), but I ended up adding a 7i85S for more Steps and a 7i84D for a few more Inputs. The idea is to have everything plugged in and relying on LinuxCNC configurations to change between Plasma and Router.
I have 1 X axis, 2 Y axis, 2 Z axis (1 plasma & 1 spindle) and 1 A axis (Rotary axis).

Now, I think I need to compile my own firmware if I want the THCADs to be on the 7i96S and also support the 7i85S right? How can I do that?
Also, I looked at 7i96s_7i85sd.pin and noticed the TB3-1 to TB3-11 have None in "Sec. func" column. Was it just forgotten, or is this by design and I will have to move my Inputs to the 7i84D?

If there is any recommendations here, please go ahead. I probably should have asked before wiring the control box, but it still easy to do any modifications right now since the box is on my desk and not in use in the CNC.
Thanks!