how to get Mesa THC values

Hello I have a Mesa 5i25 + 7i76 last weekend I have hooked up the Mesa thcad I am reviewing some examples from John but I am in doubt how to calc this values for my machine. where do they get? I have an Hyperthem 65 and the THCad 10V

setp thc.scale-offset 119000
setp thc.vel-scale 0.00037866834

# this might need to be increased
setp thc.correction-vel 0.0001

someone can help me?

echesortux wrote: Hello I have a Mesa 5i25 + 7i76 last weekend I have hooked up the Mesa thcad I am reviewing some examples from John but I am in doubt how to calc this values for my machine. where do they get? I have an Hyperthem 65 and the THCad 10V

setp thc.scale-offset 119000
setp thc.vel-scale 0.00037866834

# this might need to be increased
setp thc.correction-vel 0.0001

someone can help me?

some time ago I start a tutorial how to calibrate a THCAD10 board, it isn't finished (shame on me) but I believe that is enough to understand the principles.

jtctech.pt/wiki/index.php?title=Mesa_Thcad10_calibration

download the excel file, place the values and it's almost everything done I use the frequency divided by 32 in the tchad10.


João

There is a section on calibration for the THC in the manual...
www.mesanet.com/pdf/analog/thcadman.pdf
I then used a known voltage source such as a battery and meter to confirm the voltage in linuxcnc was correct.

# this might need to be increased
setp thc.correction-vel 0.0001

You can adjust this for your machine, as I recall if set too high the Z axis will oscillate up and down during the cut by overcompensating.

Rick G

Currently I have connected in this way (picure attached). someone can tell me if the hooked up is correct?

Looks correct to me.

JT

Hi John, how do you get this values? I am trying to understand your plasma.hal to using with my machine.

setp thc.scale-offset 119000
setp thc.vel-scale 0.00037866834

# this might need to be increased
setp thc.correction-vel 0.0001

thanks

setp thc.scale-offset 119000 = frequency 0V ?

setp thc.vel-scale 0.00037866834 = 300v/(916100Hz - 119100Hz) = 0.000376411 aprox.

setp thc.correction-vel 0.0001 ??

echesortux wrote: setp thc.scale-offset 119000 = frequency 0V ?

setp thc.vel-scale 0.00037866834 = 300v/(916100Hz - 119100Hz) = 0.000376411 aprox.

setp thc.correction-vel 0.0001 ??

1- yes, is the measured freq at 0v
2- slope of the line, I prefer to make some measurements and calc a trend line on excel to get the slope value.
3- I use a modified THC comp, so I cant help you on this one.

setp thc.correction-vel 0.0001 ??

This is by how much the value will change while correcting the height, to high and the torch will bounce like a bunny, to little and it will be to slow at going up or down, so you have to test some values there to get smooth movement. That is dependant on your setup, speed of Z axis, delay on the motor drives, etc.

echesortux wrote: Hi John, how do you get this values? I am trying to understand your plasma.hal to using with my machine.

setp thc.scale-offset 119000
setp thc.vel-scale 0.00037866834

# this might need to be increased
setp thc.correction-vel 0.0001

thanks

The THCAD manual tells you where to get the scale offset number, it's different for each card a bit I think.

JT