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Just went over my topic on building 2+2+3 plasma machines, i was sure i posted pictures of new Z axis insides, i did not! Shame on me!
Here is the old versions
www.forum.linuxcnc.org/show-your-stuff/3...uild?start=40#166228
I will try to make some time to disassemble one of the new ones and take some pictures... do remind me if i forget.
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No need for a voltage divider, install the resistors inside the plasma source and use double shielded cable to the control box where THCAD2 is.
This was even if the cable shorts to anything, nothing happens.
One resistor for each wire, 1 Mohm and 2W will do just fine for THCAD10, probably will do for THCAD2 also.

machinedude wrote:

So with a 3mm pitch belt and a 24 tooth pulley you get a pretty quick rate of travel at low speeds right out of the gate. only down side is you need some pretty fine micro stepping to deal with it. which this particular machine lacks at the moment so bigger motors and better drives are on a long wish list.

that is exactly what i have been using with good results.  i am thinking right now that i am going to put a 3:1ish reduction on it but right now i am having a hard time finding 60t pulleys that wont break the bank.  they are seriously wanting $45+ each for them.  

machinedude post=288009 userid=25766
So as long as the belts are good you save around $600 to $700 vs Gates belt's. They are out of their minds only selling 50 feet or more at a time at $13 to $14 a foot

yes that is absolutely ridiculous!  the only time ive used gates belts were some closed loop gt2 belts on a 3d printer and i noticed exactly 0 difference in lifespan or performance from other brands. 

quick question for @tommylight.  how do you handle your touch off on the z?  i was thinking of using a spring loaded switch on some simple rails using the torch head as the probe, but is that overkill?  or is there a better way of getting material height?

and @pcw, how come mesa doesnt make a voltage divider?  i was going with tommy's advice and going to use a pair of resistors, but with that much voltage, it just really makes me nervous.  i picked up a thcad2 and i would like to mount it inside of the control box, so i want as low of voltage as i can get to come out of the plasma unit into the controller.  i have enought space on the back of the unit to put a pair of avaiation plugs on the back of it, one for the switch and the other for the thc, but that still makes me leery having that much voltage come out of the unit, especially how cords and cables seem to get snagged and pulled in my world.  even with a box on the back like tommy said, i would still prefer to keep as much as i can inside the box if possible 

bobwolf wrote:

What type of mesa boards do you use or have you used?

5i25, 6i25, 7i92, 7i96, 7i95, 7i77, 7i76, 7i76E, 7i74, 7i73, 7i70, 7i71, 7i72, THCAD, ...
Probably forgot some.

bobwolf wrote:

if they are the type with serial communication (ethernet type for example) can you insert the firmware that is convenient for your machine into the internal eeprom???

I would not call Ethernet "serial", there are some differences there, but yes, some are Ethernet boards and no you can not "load" firmware, all of these require flashing the firmware once and do not need to load the firmware from the PC as it is located in their own internal memory.
And yes, anytime i needed some strange firmware that did not exist, it was generously provided by PCW (he is the owner of Mesa).
Now, this begs the question, what are you changing that often that you need to load different firmware?
I needed once, only once on a very big machine, firmware that was not standard, and once or twice for testing some strange contraptions i made, otherwise there is no need to change firmware most of the time.

Set VAD to 60 or 65, save.
The rest should be good as is, so do not touch those.

so how to use this THC settings?

This is the process I follow:
1 make sure z-axis is properly calibrated (if you command 1 inch it moves 1 inch) you can use a Bernier to adjust the Z axis Scale.
2 you can use a gauge to calibrate the float travel.

• Adjust piercing high to .5" in the default tool and save it.
• Press probe test and when the torch goes to piercing high use the gauge to measure .5" from work piece to torch.
• If measurement is not correct adjust float travel and repeat the measurement.
• Change piercing high to .125", on the default tool (not forget to save)
• Press probe test and verify piercing high is .125 in.

3 Once the Z axis is properly calibrated, we need to make sure the voltage is properly calibrated according to the plasma power supply charts.
what I do (No sure if it is the best way to do but work)

• select a thick material, may be 3/4" mild steel then set the cut high according to the power supply chart cutting high for instance for a Hyperterm Powermax 125

the Torch-to-Work Distance is 0.18" piercing height .45", Cut Speed is 42 ipm, and voltage is 164V.

• Set these settings to your default tool and make sure the working piece is as much flat as possible, 
• Cut a line, let say 6 inches but no use THC, during cut make a note of the voltage displayed.
• Then adjust the voltage scale to make sure these settings give you 164V.
• repeat the process for a 1/4" material, and verify the voltage is according to the table.

after this exercise you can set up the tools according to the Plasma power supply tables.
this is not a perfect procedure but work for me.

That you will have to find out yourself, there is no "one fits all" in plasma cutting.
Start with Hypertherm cut charts and test from there, take notes and make a list of what works best for you.

Hi, I have been cutting different materials from 1mm to 30mm which THC settings is good for me?

now the THC is working correctly. thanks very much tommy.

Notice the voltage in the GUI, now it shows 0 as it should.
Try cutting something ....

now it is working the problem was my encoder A pins it was not working so i have to change to encoder B pins.
the encoder velocity and the count is reading.
 

Encoder velocity ?
THCAD when wired correctly counts all the time, yours is idle on last picture.

The video above shows the encoder is counting in Hal show but now is not counting.

tommylight wrote:

rodw wrote:

tommylight wrote:

Open the "halshow" and check if the encoder is counting correctly.
THis is the step I told you to do earlier but you didn't

Yes you did Rod, i just reminded him.

Nothing against you Tommy. I just get frustrated when people miss a step and wonder why things are not working....
You need to be very methodical with linuxcnc connections. Check each step at a time before moving to the next!
A few more minutes now saves hours later...